The sky (or celestial dome) is everything that lies above the surface of the Earth, including the atmosphere and outer space. During daylight, the sky appears to be blue because air scatters blue sunlight more than it scatters red. At night, the sky appears to be a mostly dark surface or region scattered with stars. During the day, the Sun can be seen in the sky unless obscured by clouds. In the night sky (and to some extent during the day) the moon, planets and stars are visible in the sky. Some of the natural phenomena seen in the sky are clouds, rainbows, and aurora. Lightning and precipitation can also be seen in the sky during storms. Birds, insects, aircraft, and kites are often considered to fly in the sky. Due to human activities, smog during the day and light pollution during the night are often seen above large cities. Individual water droplets exposed to white light will create a set of collared rings. If a cloud is thick enough, scattering from multiple water droplets will wash out the set of collared rings and create a washed-out white colour. The sky can turn a multitude of colours such as red, orange, purple and yellow (especially near sunset or sunrise) when the light must pass through a much longer path (or optical depth) through the atmosphere. Because red light also scatters if there is enough air between the source and the observer, these longer wavelengths of light will also scatter significantly, making parts of the sky change colour during a sunset. As the amount of atmosphere nears infinity, the scattered light appears whiter and whiter. At higher altitudes, the sky tends toward darker colours since scattering is reduced due to lower air density; an extreme example is the moon, where there is no atmosphere and no scattering, making the sky on the moon black even when the sun is visible.

The atmosphere of Earth is the layer of gases surrounding the planet Earth that is retained by Earth's gravity. The atmosphere protects life on Earth by absorbing ultraviolet solar radiation, warming the surface through heat retention (greenhouse effect), and reducing temperature extremes between day and night (the diurnal temperature variation).
The common name air is given to the atmospheric gases used in breathing and photosynthesis. By volume, dry air contains 78.09% nitrogen, 20.95% oxygen, 0.93% argon, 0.039% carbon dioxide, and small amounts of other gases. Air also contains a variable amount of water vapour, on average around 1% at sea level, and 0.4% over the entire atmosphere. Air content and atmospheric pressure vary at different layers, and air suitable for the survival of terrestrial plants and terrestrial animals is found only in Earth's troposphere and artificial atmospheres. The atmosphere has a mass of about 5.15×1018 kg, three quarters of which is within about 11 kms of the surface. The atmosphere becomes thinner and thinner with increasing altitude, with no definite boundary between the atmosphere and outer space. The Kármán line, at 100 kms, or 1.57% of Earth's radius, is often used as the border between the atmosphere and outer space. Atmospheric effects become noticeable during atmospheric re-entry of spacecraft at an altitude of around 120 kms. Several layers can be distinguished in the atmosphere, based on characteristics such as temperature and composition. Air is mainly composed of nitrogen, oxygen, and argon, which together constitute the major gases of the atmosphere. Water vapour accounts for roughly 0.25% of the atmosphere by mass. The concentration of water vapour (a greenhouse gas) varies significantly from around 10 ppmv in the coldest portions of the atmosphere to as much as 5% by volume in hot, humid air masses, and concentrations of other atmospheric gases are typically provided for dry air without any water vapour. The remaining gases are often referred to as trace gases, among which are the greenhouse gases such as carbon dioxide, methane, nitrous oxide, and ozone. Filtered air includes trace amounts of many other chemical compounds. Many substances of natural origin may be present in locally and seasonally variable small amounts as aerosols in an unfiltered air sample, including dust of mineral and organic composition, pollen and spores, sea spray, and volcanic ash. Various industrial pollutants also may be present as gases or aerosols, such as chlorine (elemental or in compounds), fluorine compounds and elemental mercury vapour. Sulphur compounds such as hydrogen sulphide and sulphur dioxide (SO2) may be derived from natural sources or from industrial air pollution.

The average temperature of the atmosphere at Earth's surface is 14 °C or 15 °C depending on the reference. The average atmospheric pressure at sea level is defined by the International Standard Atmosphere as 101325 pascals (760.00 Torr; 14.6959 psi; 760.00 mmHg). This is sometimes referred to as a unit of standard atmospheres (atm). Total atmospheric mass is 5.1480×1018 kg (1.135×1019 lb), about 2.5% less than would be inferred from the average sea level pressure and Earth's area of 51007.2 megahectares, this portion being displaced by Earth's mountainous terrain. Atmospheric pressure is the total weight of the air above unit area at the point where the pressure is measured. Thus air pressure varies with location and weather. If the entire mass of the atmosphere had a uniform density from sea level, it would terminate abruptly at an altitude of 8.50 kms. It actually decreases exponentially with altitude, dropping by half every 5.6 kms or by a factor of 1/e every 7.64 kms, the average scale height of the atmosphere below 70 kms. However, the atmosphere is more accurately modelled with a customized equation for each layer that takes gradients of temperature, molecular composition, solar radiation and gravity into account.
In summary, the mass of Earth's atmosphere is distributed approximately as follows:
50% is below 5.6 kms.
90% is below 16 kms.
99.99997% is below 100 kms, the Kármán line. By international convention, this marks the beginning of space where human travellers are considered astronauts.
By comparison, the summit of Mt. Everest is at 8,848 mtrs; commercial airliners typically cruise between 10 kms and 13 kms where the thinner air improves fuel economy; weather balloons reach 30.4 kms and above; and the highest X-15 flight in 1963 reached 108.0 kms.

Even above the Kármán line, significant atmospheric effects such as auroras still occur. Meteors begin to glow in this region though the larger ones may not burn up until they penetrate more deeply. The various layers of Earth's ionosphere, important to HF radio propagation, begin below 100 kms and extend beyond 500 kms. By comparison, the International Space Station and Space Shuttle typically orbit at 350–400 kms, within the F-layer of the ionosphere where they encounter enough atmospheric drag to require reboosts every few months. Depending on solar activity, satellites can experience noticeable atmospheric drag at altitudes as high as 700–800 kms.

The division of the atmosphere into layers mostly by reference to temperature is discussed above. Temperature decreases with altitude starting at sea level, but variations in this trend begin above 11 kms, where the temperature stabilizes through a large vertical distance through the rest of the troposphere. In the stratosphere, starting above about 20 km, the temperature increases with height, due to heating within the ozone layer caused by capture of significant ultraviolet radiation from the Sun by the dioxygen and ozone gas in this region. Still another region of increasing temperature with altitude occurs at very high altitudes, in the aptly-named thermosphere above 90 kms.
Because in an ideal gas of constant composition the speed of sound depends only on temperature and not on the gas pressure or density, the speed of sound in the atmosphere with altitude takes on the form of the complicated temperature profile (see illustration to the right), and does not mirror altitudinal changes in density or pressure.

The density of air at sea level is about 1.2 kg/m3 (1.2 g/L). Density is not measured directly but is calculated from measurements of temperature, pressure and humidity using the equation of state for air (a form of the ideal gas law). Atmospheric density decreases as the altitude increases. This variation can be approximately modelled using the barometric formula. More sophisticated models are used to predict orbital decay of satellites. The average mass of the atmosphere is about 5 quadrillion (5×1015) tonnes or 1/1,200,000 the mass of Earth. According to the American National Centre for Atmospheric Research, "The total mean mass of the atmosphere is 5.1480×1018 kg with an annual range due to water vapour of 1.2 or 1.5×1015 kg depending on whether surface pressure or water vapour data are used; somewhat smaller than the previous estimate. The mean mass of water vapour is estimated as 1.27×1016 kg and the dry air mass as 5.1352 ±0.0003×1018 kg.

The lower boundary of the exosphere is called the exobase. It is also called exopause and 'critical altitude' as this is the altitude where barometric conditions no longer apply. Atmospheric temperature becomes nearly a constant above this altitude. On Earth, the altitude of the exobase ranges from about 500 to 1,000 kilometres depending on solar activity. The fluctuation in the height of the exobase is important because this provides atmospheric drag on satellites, eventually causing them to fall from orbit if no action is taken to maintain the orbit.

This layer is completely cloudless and free of water vapour. However non-hydrometeorological phenomena such as the aurora borealis and aurora australis are occasionally seen in the thermosphere. The International Space Station orbits in this layer, between 320 and 380 kms. The thermosphere is the layer of the Earth's atmosphere directly above the mesosphere and directly below the exosphere. Within this layer, ultraviolet radiation causes photoionization/ photodissociation of molecules present. Thermospheric temperatures increase with altitude due to absorption of highly energetic solar radiation. Temperatures are highly dependent on solar activity, and can rise to 2,000 °C. Radiation causes the atmosphere particles in this layer to become electrically charged (see ionosphere), enabling radio waves to bounce off and be received beyond the horizon. In the exosphere, beginning at 500 to 1,000 kilometres above the Earth's surface, the atmosphere turns into space. The highly diluted gas in this layer can reach 2,500 °C during the day. Even though the temperature is so high, one would not feel warm in the thermosphere, because it is so near vacuum that there is not enough contact with the few atoms of gas to transfer much heat. A normal thermometer would be significantly below 0 °C, because the energy lost by thermal radiation would exceed the energy acquired from the atmospheric gas by direct contact. In the anacoustic zone above 160 kilometres, the density is so low that molecular interactions are too infrequent to permit the transmission of sound. The dynamics of the thermosphere are dominated by atmospheric tides, which are driven by the very significant diurnal heating. Atmospheric waves dissipate above this level because of collisions between the neutral gas and the ionospheric plasma.

The International Space Station orbits within the middle of the thermosphere, between 330 and 435 kilometres (decaying by 2 kms per month and raised by periodic reboosts), whereas the Gravity Field and Steady-State Ocean Circulation Explorer satellite at 260 kilometres utilized winglets and an innovative ion engine to maintain a stable orientation and orbit.

It is convenient to separate the atmospheric regions according to the two temperature minima at about 12 kms altitude (the tropopause) and at about 85 kms (the mesopause). The thermosphere (or the upper atmosphere) is the height region above 85 kms, while the region between the tropospause and the mesopause is the middle atmosphere (stratosphere and mesosphere) where absorption of solar UV radiation generates the temperature maximum near 45 kms altitude and causes the ozone layer.

Turbulence causes the air within the lower atmospheric regions below the turbopause at about 110 kms to be a mixture of gases that does not change its composition. Its mean molecular weight is 29 g/mol with molecular oxygen (O2) and nitrogen (N2) as the two dominant constituents. Above the turbopause, however, diffusive separation of the various constituents is significant, so that each constituent follows its own barometric height structure with a scale height inversely proportional to its molecular weight. The lighter constituents atomic oxygen (O), helium (He), and hydrogen (H) successively dominate above about 200 kms altitude and vary with geographic location, time, and solar activity. The ratio N2/O which is a measure of the electron density at the ionospheric F region is highly affected by these variations. The solar X-ray and extreme ultraviolet radiation (XUV) at wavelengths < 170 nm is almost completely absorbed within the thermosphere. This radiation causes the various ionospheric layers as well as a temperature increase at these heights. While the solar visible light (380 to 780 nm) is nearly constant with a variability of not more than about 0.1% of the solar constant, the solar XUV radiation is highly variable in time and space. For instance, X-ray bursts associated with solar flares can dramatically increase their intensity over preflare levels by many orders of magnitude over a time span of tens of minutes. In the extreme ultraviolet, the Lyman α line at 121.6 nm represents an important source of ionization and dissociation at ionospheric D layer heights. During quiet periods of solar activity, it alone contains more energy than the rest of the XUV spectrum. Quasi-periodic changes of the order of 100% and more with period of 27 days and 11 years belong to the prominent variations of solar XUV radiation. However, irregular fluctuations over all time scales are present all the time. During low solar activity, about one half of the total energy input into the thermosphere is thought to be solar XUV radiation. Evidently, that solar XUV energy input occurs only during daytime conditions, maximizing at the equator during equinox.

A second source of energy input into the thermosphere is solar wind energy which is transferred to the magnetosphere by mechanisms that are not completely understood. One possible way to transfer energy is via a hydrodynamic dynamo process. Solar wind particles penetrate into the polar regions of the magnetosphere where the geomagnetic field lines are essentially vertically directed. An electric field is generated, directed from dawn to dusk. Along the last closed geomagnetic field lines with their footpoints within the auroral zones, field aligned electric currents can flow into the ionospheric dynamo region where they are closed by electric Pedersen and Hall currents. Ohmic losses of the Pedersen currents heat the lower thermosphere (see e.g., Magnetospheric electric convection field). In addition, penetration of high energetic particles from the magnetosphere into the auroral regions enhance drastically the electric conductivity, further increasing the electric currents and thus Joule heating. During quiet magnetospheric activity, the magnetosphere contributes perhaps by a quarter to the energy budget of the thermosphere. This is about 250 K of the exospheric temperature. During very large activity, however, this heat input can increase substantially, by a factor of four or more. That solar wind input occurs mainly in the auroral regions during the day as well as during the night.

Heating, predominately by tidal waves, occurs mainly at lower and middle latitudes. The variability of this heating depends in general on the meteorological conditions within troposphere and middle atmosphere, and may not exceed about 50%.In contrast to solar XUV radiation, magnetospheric disturbances, indicated on the ground by geomagnetic variations, show an unpredictable impulsive character, from short periodic disturbances of the order of hours to long standing giant storms of several day's duration. The reaction of the thermosphere to a large magnetospheric storm is called thermospheric storm. In addition, due to the impulsive form of the disturbance, higher order terms are generated which, however, possess short decay times and thus quickly disappear. The sum of these modes determines the "travel time" of the disturbance to the lower latitudes, and thus the response time of the thermosphere with respect to the magnetospheric disturbance. Important for the development of an ionospheric storm is the increase of the ratio N2/O during a thermospheric storm at middle and higher latitude. An increase of N2 increases the loss process of the ionospheric plasma and causes therefore a decrease of the electron density within the ionospheric F-layer (negative ionospheric storm). The mesosphere is the third highest layer of Earth's atmosphere, occupying the region above the stratosphere and below the thermosphere. It extends from the stratopause at an altitude of about 50 kms to the mesopause at 80–85 kms above sea level. Temperatures drop with increasing altitude to the mesopause that marks the top of this middle layer of the atmosphere. It is the coldest place on Earth and has an average temperature around −85 °C. Just below the mesopause, the air is so cold that even the very scarce water vapour at this altitude can be sublimated into polar-mesospheric noctilucent clouds. These are the highest clouds in the atmosphere and may be visible to the naked eye if sunlight reflects off them about an hour or two after sunset or a similar length of time before sunrise. They are most readily visible when the Sun is around 4 to 16 degrees below the horizon. A type of lightning referred to as either sprites or ELVES, occasionally form far above tropospheric thunderclouds. The mesosphere is also the layer where most meteors burn up upon atmospheric entrance. It is too high above Earth to be accessible to aircraft and balloons, and too low to permit orbital spacecraft. The mesosphere is mainly accessed by sounding rockets.

The Earth's thermosphere also includes the region of the atmosphere called the ionosphere. The ionosphere is a region of the atmosphere that is filled with charged particles. The high temperatures in the thermosphere can cause molecules to ionize. This is why an ionosphere and thermosphere can overlap. Scientists call the ionosphere an extension of the thermosphere. So technically, the ionosphere is not another atmospheric layer. The ionosphere represents less than 0.1% of the total mass of the Earth's atmosphere. Even though it is such a small part, it is extremely important. The upper atmosphere is ionized by solar radiation. That means the Sun's energy is so strong at this level, that it breaks apart molecules. So there ends up being electrons floating around and molecules which have lost or gained electrons. When the Sun is active, more and more ionization happens. Different regions of the ionosphere make long distance radio communication possible by reflecting the radio waves back to Earth. It is also home to auroras. Temperatures in the ionosphere just keep getting hotter as you go up. The ionosphere is broken down into the D, E and F regions. The breakdown is based on what wavelength of solar radiation is absorbed in that region most frequently. The D region is the lowest in altitude, though it absorbs the most energetic radiation, hard x-rays. The D region doesn't have a definite starting and stopping point, but includes the ionization that occurs below about 90kms. The E region peaks at about 105kms. It absorbs soft x-rays. The F region starts around 105kms and has a maximum around 600kms. It is the highest of all of the regions. Extreme ultra-violet radiation (EUV) is absorbed there. On a more practical note, the D and E regions reflect AM radio waves back to Earth. Radio waves with shorter lengths are reflected by the F region. Visible light, television and FM wavelengths are all too short to be reflected by the ionosphere. So your t.v. stations are made possible by satellite transmissions. Invisible layers of ions and electrons are found in the Earth's atmosphere. We call this region of atmosphere the ionosphere. The main source of these layers is the Sun's ultraviolet light which ionizes atoms and molecules in the Earth's upper atmosphere. During this process, electrons are knocked free from molecules or particles in the atmosphere. Flares and other big events on the Sun produce increased ultraviolet, x-ray and gamma-ray photons that arrive at the Earth just 8 minutes later (other particles from the Sun may arrive days later) and dramatically increase the ionization that happens in the atmosphere. So, the more active the Sun, the thicker the ionosphere.

The stratosphere is the second major layer of Earth's atmosphere, just above the troposphere, and below the mesosphere. It is stratified in temperature, with warmer layers higher up and cooler layers farther down. This is in contrast to the troposphere near the Earth's surface, which is cooler higher up and warmer farther down. The border of the troposphere and stratosphere, the tropopause, is marked by where this inversion begins, which in terms of atmospheric thermodynamics is the equilibrium level. At moderate latitudes the stratosphere is situated between about 10–13 kms and 50 kms altitude above the surface, while at the poles it starts at about 8 kms altitude, and near the equator it may start at altitudes as high as 18 kms. Within this layer, temperature increases as altitude increases (see temperature inversion); the top of the stratosphere has a temperature of about −3°Cs, just slightly below the freezing point of water.s The stratosphere is layered in temperature because ozone (O3) here absorbs high energy ultraviolet (UVB and UVC) radiation from the Sun and is broken down into the allotropes of atomic oxygen (O1) and common molecular oxygen (O2). The mid stratosphere has less UV light passing through it; O and O2 are able to combine, and this is where the majority of natural ozone is produced. It is when these two forms of oxygen recombine to form ozone that they release the heat found in the stratosphere. The lower stratosphere receives very low amounts of UVC; thus atomic oxygen is not found here and ozone is not formed (with heat as the byproduct). This vertical stratification, with warmer layers above and cooler layers below, makes the stratosphere dynamically stable: there is no regular convection and associated turbulence in this part of the atmosphere. The top of the stratosphere is called the stratopause, above which the temperature decreases with height. Methane (CH4), while not a direct cause of ozone destruction in the stratosphere, does lead to the formation of compounds that destroy ozone. Monatomic oxygen (O) in the upper stratosphere reacts with methane (CH4) to form a hydroxyl radical (OH·). This hydroxyl radical is then able to interact with non-soluble compounds like chlorofluorocarbons, and UV light breaks off chlorine radicals (Cl·). These chlorine radicals break off an oxygen atom from the ozone molecule, creating an oxygen molecule (O2) and a hypochloryl radical (ClO·). The hypochloryl radical then reacts with an atomic oxygen creating another oxygen molecule and another chlorine radical, thereby preventing the reaction of monatomic oxygen with O2 to create natural ozone.

Commercial airliners typically cruise at altitudes of 9–12 kms (30,000–39,000 ft) in temperate latitudes (in the lower reaches of the stratosphere). This optimizes fuel burn, mostly due to the low temperatures encountered near the tropopause and low air density, reducing parasitic drag on the airframe. (Stated another way, it allows the airliner to fly faster for the same amount of drag.) It also allows them to stay above hard weather (extreme turbulence).
Concorde would cruise at mach 2 at about 18,000 mtrs (59,000 ft), and the SR-71 would cruise at mach 3 at 26,000 mtrs (85,000 ft), all still in the stratosphere.

Because the temperature in the tropopause and lower stratosphere remains constant (or slightly decreases) with increasing altitude, very little convective turbulence occurs at these altitudes. Though most turbulence at this altitude is caused by variations in the jet stream and other local wind shears, areas of significant convective activity (thunderstorms) in the troposphere below may produce convective overshoot. Although a few gliders have achieved great altitudes in the powerful thermals in thunderstorms, this is dangerous. Most high altitude flights by gliders use lee waves from mountain ranges and were used to set the current record of 15,447 mtrs. The stratosphere is a region of intense interactions among radiative, dynamical, and chemical processes, in which the horizontal mixing of gaseous components proceeds much more rapidly than in vertical mixing. An interesting feature of stratospheric circulation is the quasi-biennial oscillation (QBO) in the tropical latitudes, which is driven by gravity waves that are convectively generated in the troposphere. The QBO induces a secondary circulation that is important for the global stratospheric transport of tracers, such as ozone or water vapour. Also, some bird species have been reported to fly at the lower levels of the stratosphere.

The troposphere is the lowest portion of Earth's atmosphere. It contains approximately 75% of the atmosphere's mass and 99% of its water vapour and aerosols. The average depth of the troposphere is approximately 17 kms in the middle latitudes. It is deeper in the tropics, up to 20 kms, and shallower near the polar regions, approximately 7 kms in winter. The lowest part of the troposphere, where friction with the Earth's surface influences air flow, is the planetary boundary layer. This layer is typically a few hundred meters to 2 kms deep depending on the landform and time of day. The border between the troposphere and stratosphere, called the tropopause, is a temperature inversion.
The word troposphere derives from the Greek: tropos for "change" reflecting the fact that turbulent mixing plays an important role in the troposphere's structure and behaviour. Most of the phenomena we associate with day-to-day weather occur in the troposphere.

The chemical composition of the troposphere is essentially uniform, with the notable exception of water vapour. The source of water vapour is at the surface through the processes of evaporation and transpiration. Furthermore, the temperature of the troposphere decreases with height, and saturation vapour pressure decreases strongly as temperature drops, so the amount of water vapour that can exist in the atmosphere decreases strongly with height. Thus the proportion of water vapour is normally greatest near the surface and decreases with height. Since temperature in principle also depends on altitude, one needs a second equation to determine the pressure as a function of height.

The ionosphere is a region of the atmosphere that is ionized by solar radiation. It is responsible for auroras. During daytime hours, it stretches from 50 to 1,000 kms and includes the mesosphere, thermosphere, and parts of the exosphere. However, ionization in the mesosphere largely ceases during the night, so auroras are normally seen only in the thermosphere and lower exosphere. The ionosphere forms the inner edge of the magnetosphere. It has practical importance because it influences, for example, radio propagation on Earth.

A lightning storm presents no special hazard to characters who take simple precautions. However, the word “simple” in this context is an expression of complexity and not necessarily a measure of difficulty. For instance, it may not be at all easy for a character to find somewhere to hole up during a lightning storm if he’s in the middle of a flat, featureless plain that extends for hundreds of metres, or kilometres, in every direction. The most important precaution to take against being struck by lightning in the outdoors is to get rid of, and get away from, any metal armour, weapons, and equipment. If time permits, it is a good idea to scatter individual pieces of metal (the parts of a suit of armour, for instance) over an area at least several yards in diametre to minimize the possibility of lightning hitting the armour and gear. Heaping everything up in a pile for easier access later is asking for trouble, especially if the top of the pile is higher than any surrounding terrain. Second, if solid cover is not available, get as low as possible, either by dropping flat on the ground or lying in a ditch or depression. Lightning is not immediately absorbed into the ground after it hits; the electrical force may travel some distance (up to several hundred metres, if the stroke is very powerful) along the ground before dissipating, and along its route it will seek out gullies, ruts, and other such low spots. Thus, someone lying in a ditch is not entirely safe, but this course of action is still better than presenting
oneself as a target above ground level. (Contrary to popular belief, lightning does not travel from the clouds to the ground but rather in the opposite direction; even so, we tend to speak of lightning “hitting the ground” because of the visual impression created when a strike occurs). Even an apparently safe place, such as a rock overhang, is not
necessarily the best place to be. If lightning strikes on a ridge above the overhang, it may travel downward and into the enclosure as described above. Still, an alcove of this sort is much more preferable than a more exposed position.
Taking cover under a lone tree is not a good course of action at all; if the tree is taller than the surrounding terrain, it is a prime target for lightning - and even if the electrical force of the lightning stroke does not travel down through the tree, a character is still vulnerable to damage from falling debris (at the DM’s discretion) if the tree is hit.

4. Altitude Sickness

Rewarming the total body in a warm water bath should be done only in a hospital environment because of the increased risk of cardiac arrest and rewarming shock. One of the quickest ways to get heat to the inner core is to give warm water enemas. Such an action, however, may not be possible in a survival situation. Another method is to wrap the victim in a warmed sleeping bag with another person who is already warm; both should be naked. The individual placed in the sleeping bag with victim could also become a hypothermia victim if left in the bag too long. If the person is conscious, give him hot, sweetened fluids. One of the best sources of calories is honey or dextrose; if unavailable, use sugar, cocoa, or a similar soluble sweetener. Do not force an unconscious person to drink. There are two dangers in treating hypothermia; rewarming too rapidly and after drop. Rewarming too rapidly can cause the victim to have circulatory problems, resulting in heart failure. After drop is the sharp body core temperature drop that occurs when taking the victim from the warm water. Its probable muse is the return of previously stagnant limb blood to the core (inner torso) area as recirculation occurs. Concentrating on warming the core area and stimulating peripheral circulation will lessen the effects of after drop. Immersing the torso in a warm bath, if possible, is the best treatment.

A human needs to drink at least one quart of water each day, assuming he doesn’t get involved in any strenuous activity. Others require less or more water, proportionate to their size. For each day that a character does not get sufficient water, he takes a -1 penalty to all STR, DEX and CON tests from dehydration (no armour provides protection). Additionally, he receives a penalty to his recovery equal to the number of days he has gone without adequate water. This damage may be added to any damage inflicted by heat exposure.

If a character becomes exhausted when the effective temperature for that character is high enough to require a
Constitution Check for damage, then he has suffered heatstroke. He will immediately collapse, with a 50°/o chance of lapsing into unconsciousness. Even if he remains conscious, he will be incapable of moving or defending himself (unlike a normally exhausted character, who can still fight if necessary). From this time until he recovers, all of his constitution Checks will automatically fail, and he will suffer maximum damage whenever damage from heat is
indicated. The treatment for heatstroke involves much more than simply getting the victim into a tolerable environment - he must be cooled quickly and drastically by immersion in very cold water or by some magical means that cools him and keeps him cool for at least an hour (see the section on Magic in the Wilderness). If a heatstroke victim does not receive treatment within three turns after the onset of the condition, he will suffer a drop in constitution of one point per turn thereafter, and if constitution reaches zero, the character dies. If he is treated after the constitution loss has begun, he will naturally regain one point of constitution for every turn that he remains in the treatment up to a maximum of two-thirds (rounded up) of the points that were lost.

Clothing that becomes water-soaked will not be damaged as such, but if it is porous and becomes waterlogged by prolonged exposure to moisture it will lose some of its insulating quality until it is taken off and dried out. The wetness and loss of insulating ability may result in an alteration of the personal temperature for the character wearing the clothes: Someone decked out in wet clothing when the environment is at an effective temperature of
30 degrees may be treated as if the effective temperature (for purposes of determining his personal temperature) was 10 degrees colder. Remember that clothing worn under metal armour is not necessarily safe from moisture, unless a character is completely covered with tight-fitting, leakproof armour - and this sort of attire can be dangerous in cool or cold weather, since it does not allow the body to “breathe” naturally. Metal armour or equipment that is exposed to significant moisture will begin to rust if it is not dried off or dried out at least once every two days and oiled or otherwise protected at least once every two weeks. Rusted armour will not suffer a penalty to armour class, but the Dungeon Master may wish to allow the possibility that such armour will weaken or break if it is hit; for instance, if an opponent in melee combat makes an unmodified “to hit” roll of 20 and does more than four points of damage with a weapon, there is a 1 in 3 chance that the armour will crack or split and thereafter be treated as if it had an armour class one step worse. On a second hit of this sort, the armour will break entirely and be useless until it is repaired. Articles of leather (such as boots, armour, and backpacks or other accessory equipment) are not usually damaged by excess moisture as long as they are waterproofed periodically; even an item of leather that is not waterproofed will not be directly harmed by becoming waterlogged, but the water may seep through and moisten or harm materials (clothing, equipment, etc.) on the inside of the leather. Boots are somewhat of an exception to this general statement; because of the stress they are under when they are being used, water-soaked boots may begin to come apart at the seams as the hide softens and weakens from being moistened. If boots are not thoroughly dried out once every two days or so, they may start to show signs of this deterioration. Generally, the greatest danger to waterlogged leather is the owner’s failure to dry it out properly. If too much heat is applied to the leather, it will certainly dry out - but in the process it will become cracked, and the seams will be weakened even more than they might have been if they had been allowed to remain wet. (Treat cracked leather armour the same as rusted metal armour for determining whether it is affected by a blow during combat.) Leather gear should also be kept free of mud and grime; an excessive amount of dried mud can crack leather almost as quickly as an excessive application of heat. Rope expands when it gets wet. A knot made in a dry rope will be very difficult to untie quickly if the rope has been drenched in the meantime. Conversely, a knot made with a wet rope will be weaker or looser, or both, after the rope dries out. Certain items of equipment will be less useful, or perhaps altogether
useless, if they take on moisture. Vegetable matter may develop mould or begin to rot if it is kept for too long in a
moisture-laden environment, especially at high temperatures. Nonmagical ink will run and bleed across the surface it is written on, making instructions and maps at least partially illegible. Spell scrolls, protection scrolls, and other types of magical writing are presumed to be written in waterproof ink - but the substance on which the ink was placed is not necessarily waterproof as well. Arrows that get wet will not fly true until the fletching is dried out; any character who is not a specialist in the use of his bow will take a - 1 penalty “to hit” and damage when firing a waterlogged arrow.

Forward Speed: Forward speed is the number of squares a flying creature traverses during the course of its movement for the round. Some flight manoeuvres (such as turning in place) use up flying movement but don't contribute to forward speed. Many flyers must maintain a minimum forward speed each round. If they fail to do so, they stall (see Minimum Forward Speed).

Direction of Travel: Though the D&D game doesn't require you to keep track of which direction creatures face, flying movement usually restricts their ability to turn and that does require you to keep track of facing. For purposes of flying movement, a creature always faces the same direction as its movement. When a creature ends its flying movement for the turn, place a mark or a marker on the grid so you know which direction in which it would travel. When it is time for the creature to move again, it resumes moving in that direction. The creature's direction of travel in no way limits where it can make melee or ranged attacks. A flying creature (if armed) threatens the spaces around it not matter what its manoeuvrability or which direction it flies.

Altitude: This is simply how high above the ground a flying creature happens to be. If keeping track of flyers' altitudes relative to the ground proves inconvenient, choose some other reference point, but make sure that all creatures in an aerial encounter use the same reference point to measure altitude. Altitude is measured from the ground (or other reference point) to the bottom of a flying creature's space. The top of a creature's space usually sticks up above its altitude and the creature usually can reach up farther than that. If an aerial encounter contains creatures bigger than Medium size, it can prove helpful to indicate how high up each creature extends. Because maps and battle grids usually are two-dimensional, you must write down each flying creature's altitude at the end of its movement. It's usually best to record altitude directly on the grid. Several flying creatures can occupy the same square on your grid it they're at different altitudes.

Minimum forward Speed: If a flying creature fails to maintain its minimum forward speed, it must land at the end of its movement. If it is too high above the ground to land, it stalls. A creature in a stall falls straight down, descending 45 metres in the first round of falling. If this distance brings it to the ground, it takes falling damage. If the fall doesn't bring the creature to the ground, it must spend its next turn recovering from the stall. It must succeed on a DEX save to recover. Otherwise it falls another 90 metres. If it hits the ground, it takes falling damage. Otherwise, it has another chance to recover on its next turn. Keep track of minimum forward speed by the turn, not by the move. As noted earlier, only moving from square to square counts toward minimum forward speed. Movement spent turning in place doesn't count. In some cases, a creature may spend part of its turn on the ground (or perhaps on a flying mount or flying device). If the creature uses a move or standard action on the ground, it need maintain only half its minimum forward speed once it takes to the air. If a flying creature moves along the ground and then takes to the air as part of the same move action, it must maintain all of its minimum forward speed to avoid stalling.

Hover: Hover is the ability to stay in one place while airborne. It can instead hover as a move action and, as part of that move action, can move at half speed in any direction it likes (including straight up, straight down, or backward). Before or after it moves, the hovering creature can turn to face any direction it likes. When it stops hovering, it can resume ordinary flight in any direction in which it could normally fly. Before or after it does this hovering movement, the creature can turn to face any direction it likes. When it stops hovering, the creature can resume ordinary flight in any direction in which it could normally fly. If a creature begins its turn hovering, it can hover in place for the turn (no matter what its manoeuvrability) and take a full-round action. A hovering creature cannot make wing attacks, but it can attack with all other limbs and appendages it could use in a full attack. The creature can instead use a breath weapon or cast a spell instead of making physical attacks, if it could normally do so.

Move Backward: This is the ability to move backward without turning around.

Reverse: A creature can use up 1.5 metres of its speed to start flying backward.

Turn: How much the creature can turn after covering the stated distance.

Turn in Place: A creature can use some of its speed to turn in place. (This represents the creature slowing down and banking hard to make a tight turn.) The extra movement spent turning does not count toward minimum forward speed; a creature that turns too sharply at low speeds stalls.

Maximum Turn: This is how much the creature can turn in any one space. No matter how much movement the creature spends on turning, it can't change direction more than this in a single square.

Up Angle: The up angle is the maximum angle at which the creature can climb through the air. A creature with an up angle of 60º must move ahead at least 1.5 metres for every 3 metres it climbs. A creature with an up angle of 45º must move ahead at least 1.5 metres for every 1.5 metres it climbs.

Up Speed: Up speed is how fast the creature can move while gaining at least 3 metres of altitude; this represents the energy the flyer loses when climbing. The creature cannot expend more movement than its up speed allows, even if that movement is not forward movement. If the creature climbs and dives in the same turn, any bonus movement it gains from the dive is not limited by the creature's up speed.

Down Angle: The down angle is the maximum angle at which the creature can dive through the air. A creature with a down angle of 45º must move ahead at least 1.5 metres for every 1.5 metres it climbs.

Down Speed: Any flying creature can fly down at twice its normal flying speed. An easy way to track diving movement is to allow it 1.5 metres of bonus movement for every 1.5 metres it descends, to a maximum of twice its normal flying speed. The creature can use the extra movement for any kind flying movement it normally could perform, except for hovering. Downward movement in a stall or freefall does not increase a creature's speed. Instead, the creature falls straight down at a fixed rate.

Between Down and Up: An average, poor, or clumsy flier must fly level for a minimum distance after descending and before climbing (but it can turn). Any flier can begin descending after a climb without an intervening distance of level flight.

Climbing and Diving in a Tight Space: Creatures that cannot fly straight up usually can ascend in a spiral by circling as they climb. Because most creatures that can't fly straight up also have minimum forward speeds of half their base flying speeds and can move at only half speed when climbing, its difficult for them to turn in place while climbing because doing so requires them expend extra movement that does not count as forward movement (though many creatures can do so by making a double move). A creature's up angle also determines how much altitude it can gain during a move action. Likewise, creatures that cannot fly straight down can descend in a spiral. Because creatures that have a limited down angles cannot turn in place, they cannot make their descending spirals any tighter than their turning radius normally allows. Because flying creatures descend at two to four times the speed they can ascend (most creatures ascend at half speed but descend at double speed), they lose altitude far more quickly than they can gain it.

Stalling and Freefalling: Stalling represents the failure of a flying creature's wings (or other motive agent) to keep the creature aloft. A stalling creature falls, but it wings provide considerable drag and tend to slow the creature's fall. As noted earlier, a creature falls 45 metres during the first round spent stalling, and it falls 90 metres each round thereafter. Wingless flyers that stall still have some residual lift and fall more slowly than non-flyers. A flying creature that cannot maintain its minimum forward speed because it has been rendered unconscious, has become paralyzed, has become magically held, or becomes unable to move for some other reason stalls at the beginning of its first turn after the debilitating effect occurs. A stalling creature can take no actions, except to recover from the stall. It loses its Dexterity bonus to Armour Class (if any) while stalling. A stalling creature falls more or less straight down, but it also tumbles and spins erratically. Melee or ranged attacks made against a stalling creature have a 20% miss chance. A nonflyer (or flyer falling through the air) freefalls rather than stalls. A creature in freefall drops 150 metres the first round and 300 metres each round thereafter. While in freefall, a creature can attempt a single action each round. It must make a Dexterity or Strength check to avoid dropping any item it tries to use. Spellcasting is possible, but doing so requires a Concentration check.

Deliberately Freefalling: A flying creature can simply stop flying and allow itself to drop like a stone. Exiting a freefall requires a full-round action (during which the creature falls 150 or 300 metres).

Fast Freefalls: A creature with a fly speed can propel itself downward as a move action, adding up to twice its flying speed to the distance it freefalls.

Catching: As a full-round action, a flyer can catch a freefalling creature or object, or a stalling creature, provided that the falling creature or object is at least one size category smaller than the creature attempting the catch. To make the catch, the creature must make a successful melee touch attack to grab the falling creature or object (a creature can voluntarily forego any Dexterity bonus to AC if desired). If the grab succeeds, the catching creature must make a DEX save to keep flying. If the save fails by 4 or less, the catcher drops the falling creature or object. If the save fails by 5 or more, the catcher drops the falling creature or object and stalls if it has a minimum forward speed. If the catcher does not have a minimum forward speed, it falls D4 x3 metres.

Obstacles and Collisions: Because flying creatures cannot always change direction when they wish to, they must take great care to avoid blundering into obstacles or into other creatures. To turn and avoid an obstacle at its own altitude, a flying creature must be able to turn in place. If it cannot turn in place, it needs at least 1.5 metres of space between it and the obstacle if it wishes to turn to avoid a collision (because in an aerial turn you move into the square ahead of you and then turn left or right 45° ). It cannot move diagonally past a corner in the air or on the ground, so any turn you make must carry you past an obstacle's corner before you can fly past it. If turning to avoid an obstacle isn't possible, it may be possible to climb over or dive under the obstacle. A creature with maximum up or down angle of 45° needs at least 1.5 metres of clear space between it and an obstacle for every 1.5 metres it must climb or dive to get over or under the obstacle (you can't move past a corner on a diagonal, even when climbing or diving). A creature with a maximum up or down angle of 60° needs at least 1.5 metres of clear space between it and an obstacle for every 3 metres it must climb or dive to get over or under the obstacle.

Flying past another creature works much like flying past an obstacle except that you can move on a diagonal to get past a creature. This makes it slightly easier to pass by without colliding. If you fly into an obstacle and you cannot land there, you must make a DEX save to avoid damage. If you fail the save, you and the object you strike take damage as though an object of your weight fell a distance equal to half your flying speed before you hit. (If it isn't clear what your speed before the collision was, use your flying speed during your previous turn.) Your flying movement stops when you strike, forcing you to stall (even if you don't have a minimum forward speed) and fall straight down. If you're still conscious after the collision, you can make DEX check to catch yourself and keep from falling. You can freely pass through your allies' spaces in the air just as you can on the ground. If you fly into a creature that is not your ally, you effectively attempt to overrun it. You can execute a bull rush against the creature instead, if you wish. An overrun or bull rush normally requires a standard action. If you accidentally enter an enemy's space you must make a DEX save; if you fail, you stall (even if you don't have a minimum forward speed). If you succeed, you can continue with your accidental bull rush or overrun, but you suffer a -4 penalty to all the opposed checks you make to resolve the bull rush or overrun. As with an overrun attack, the creature can decide not to block your movement, though this might cause the creature to stall (see the section on overruns). If so, you simply move through its space (even if you decide to bull rush the creature). You cannot stop in another creature's square, however, and if your speed isn't sufficient to carry you through the other creature's space, you must attempt an overrun or bull rush. If the creature is too small to overrun, you must try to bull rush it instead if you can't pass through its space. If the creature is too big to overrun, you strike it just as if it were an obstacle, and you and the creature take nonlethal damage. Both you and the creature you strike make DEX saves to avoid damage, but the creature you strike gets a +4 bonus for each size category it is bigger than you. You stall just as if you struck an obstacle. The creature you strike stalls if it fails its DEX save. If you are at least three size categories smaller than the creature whose space you are entering (or if you are Tiny, Diminutive, or Fine size) you can enter the creature's space without colliding, bull rushing, or overrunning, but entering the creature's space provokes an attack of opportunity. Likewise, if you are at least three size categories smaller than the creature whose space you are entering, you also can enter the creature's space without colliding, bull rushing, or overrunning, but entering the creature's space provokes an attack of opportunity.

Actions while Flying: Most actions work exactly the same way in the air as they do on the ground; exceptions are noted here. A creature with a minimum forward speed usually cannot use full-round actions in the air unless those actions allow it to move forward at least at its minimum speed. Flying spellcasters can cast their spells without too much difficulty; however, aerial spellcasters often encounter some problems other spellcasters do not. The rules for flanking apply in the air. It is possible, however, to flank a flying creature from the top and bottom. Aerial combat takes place in three dimensions, and each flying creature occupies a roughly cubical space and can reach above and below itself. An aerial bull rush requires the attacker to ram a foe, which can prove risky for both the attacker and the defender. Flying creatures can use the charge action. A flying charge must be in straight line and most cover at least 3 metres (2 squares). A flyer can charge while diving, but not while gaining more than 1.5 metres altitude.

High Wind Speeds: Flying in high winds adds penalties on your Fly checks as noted below. "Halted" means that creatures of that size or smaller must succeed on a DEX Fly check to move at all so long as the wind persists. "Pushed back" means that creatures of that size or smaller must make a DEX Fly check or be blown back 2D6 × 3 metres and take 2D6 points of nonlethal damage. This check must be made every round the creature remains airborne. A creature that is blown away must still make a DEX Fly check to move due to also being checked.

Air to air combat can be broken down into essentially two elements; combat which occurs without the opponents seeing each other and the more direct Dogfighting.

Long distance combat involves little manoeuvring, just two or more aircraft separated by dozens of miles, using their radar and other sensors to line up missile shots. This sort of aerial sniping merely requires the pilot to make a successful Pilot skill roll to detect the enemy in the first place, and then a successful Thac0 roll prior to each shot. The biggest issue with modern combat is missile velocity and range. Some missiles (especially medium range and long range missiles) can take several melees to reach their target. The defender can attempt to dodge or shoot down the incoming missile, but the missile can lock back on the next melee (with nothing but the missiles onboard guidance bonus). If the relock on fails the next melee, the missile has lost the target entirely.

Dogfighting involves the attacker and defender each manoeuvring to place each other in their sights, while attempting to prevent the other from doing so. They manoeuvre in three dimensions accelerating, braking, diving, climbing, and turning to exploit their aircrafts capabilities. Each player in initiative order chooses a target at the start of each melee round. The target chosen must then choose their response. Available options are for the pilot to attempt to escape the dogfight, the pilot to try to outmanoeuvre the other and get into a firing position, or for the pilot to focus on attacking another target at the risk of being shot down in the process. The participants roll a D20 and add their modifiers. Whichever player has the higher result has managed to manoeuvre into position to fire at their target. The faster an aircraft travels, the less manoeuvrable it becomes. as a result it is rare for dogfighting to occur at supersonic speeds. Basically there's a -1 penalty for every level of Mach speed, thus Mach 3 would incur a -3 modifier.

As explained here each aircraft has; an Armour Class (AC) rating, an Acceleration/Deceleration Factor (A/DF); Hit Points (HPs); a manoeuvre rating (MR); and the vehicle's Speed.

Aircraft move just like ground vehicles, but fixed-wing aircraft (airplanes and jets but not helicopters or craft capable of Vertical Take-Off and Landing) can never go below one quarter of their Top Speed while flying or they stall and automatically lose D4 metres of altitude at the end of their movement.

Should an aircraft hit the ground while moving forward, it suffers damage normally for its current speed (D6 per
1.5 metres of movement, rounded down). A wrecked aircraft plummets 6 metres toward the ground immediately on being wrecked, then 12 metres per round afterward. Damage for anyone on board the aircraft when it hits is figured as usual.

A pilot can try to save his aircraft—even if it is wrecked—by making a crash landing. This is a Piloting roll at -4. If he makes it, halve the damage for the landing. If the roll is failed, the craft takes damage as usual.

Aerial Initiative
Initiative works in aerial combat much the same way as it does in standard combat, except for one important difference. Flying creatures with an Intelligence of 8 or more roll initiative and take all their actions separately from their rider. Otherwise, the rider rolls initiative both for himself and his mount. If the rider chooses to allow his mount to fly without direction, the mount moves on its initiative count and the rider may use his actions as normal. Otherwise, a rider must use a move-equivalent action to direct his mount as normal. In this case, the mount delays its action to the rider’s count or moves on the rider’s initiative, as appropriate. Remember that a Ride check may be necessary for mounts that are not trained for combat.

Unlike in standard combat, in air combat the direction in which a flying creature points is often extremely important.
Facing determines which direction the creature must move and dictates manoeuvres for flyers. A flying creature can only attack a creature in its front arc. A creature’s front arc extends in a straight line to the right and left of its current position and all areas extending out from that line in the direction of the creature’s current facing. The remaining area behind the creature is its rear arc. These flyers cannot simply turn around to confront an enemy that approaches from the rear, as per the standard flight manoeuvrability rules. Some have the ability to hover in place. These creatures have neither a front or rear arc. Much like ground combatants, they can respond to threats and direct their attacks in any direction. A creature that attacks an enemy while in its rear arc is considered to have flanked its target. Flying creatures with levels in barbarian or rogue gain the benefit of their uncanny dodge ability when attacked from their rear arc in aerial combat. These nimble flyers are capable of tracking opponents in their rear arc and responding to their attacks.

Aerial Manoeuvres:
Stunt (-2): A plane on the table-top that needs to perform a barrel roll, fly through a narrow canyon, storm through a barn, or some other fantastic stunt may appear to move in a straight line, but must actually make important but minute adjustments. All of these efforts require a Piloting roll. Failure means the aircraft goes out of control.

Pop-Up (0): Helicopters, VTOLs, and other aircraft capable of hovering can hide behind cover, rise, attack, and then descend again—usually before the stunned enemy can react. This manoeuvre simply allows the pilot to ascend above an obstacle and then descend again in the same move, so that he’s only vulnerable to opponents with Hold actions. It takes a Piloting roll to ascend and fire in time to descend again. If failed, the craft simply stays at its firing altitude or fails to fire—pilot’s choice.

Power Dive (0): A pilot can enter a controlled power dive by making a Piloting roll. If failed, he loses control. If successful, he may descend up to 24 metres per round.

Sharp turn (-1): You may use expert handling to make more turns in a round, or sharper turns, than your plane could normally make. Determine how many extra turns you wish to make that round. If you wish to make an especially sharp turn (i.e., make 2-45 degree turns in a space instead of only 1) each additional 45 degree turn in the space counts as an extra turn for this purpose. Thus, a ship that can normally make 2 turns per round that instead wants to make 3 turns all in the same space would count as making 3 extra turns for this purpose (1 extra turn, +2 for making two additional turns in the same space). If this check is made successfully, the plane turns as desired.

Climb (0): By turning a ship up, the pilot can ascend quicker than normal, adding the ship’s normally-horizontal movement to the distance climbed. Just as when diving, standing creatures must pass a DEX save or fall prone. Climbing is similar to diving, except only half of the horizontal movement sacrificed is added to the distance climbed. Failing the pilot check causes the ship to stall and go into freefall (described under conditions below).

Defensive Piloting (-1): You take evasive action, granting your vehicle an extra +1 dodge bonus to AC.

Offensive Piloting (-1): You manoeuvre your vehicle in such a way as to aid your gunners. Any attack roll made by a creature aboard your vehicle against a target not aboard your vehicle gains a +1 bonus to their Thac0 roll.

Ram (0): When two planes enter the same space at the same altitude band, there is a chance they will crash into each other. Other times, the pilot of a plane may deliberately crash into a building or creature in an attempt to destroy it. When a plane crashes into another plane, creature, or object, they are performing a ramming manoeuvre. If both ship pilots want to ram each other, the ram happens automatically. If both pilots don’t wish to ram each other, the ram does not happen. When one party wants to ram and the other doesn’t, the pilot attempting to initiate the ram makes an attack roll against their intended target. There are three ways one ship may ram another:
Head-on Collision: When two ships ram into each other, their speeds are added together. Each ship suffers an additional D6 damage for every point of their combined speeds.
Side Collision: When one ship rams into the side of another ship, both ships suffer D6 points of damage for every point of the ramming ship’s speed.
Back Collision: When one ship rams into the back of another ship, subtract the speed of the targeted ship from the speed of the ramming ship. Both ships suffer D6 damage for every point left in the ramming ship’s speed (minimum: 0). If a ship is equipped with a ram, it deals extra damage when performing a ramming manoeuvre and only suffers half damage itself when it rams into another target. If two ships ram into each other (a head-on collision) and both are equipped with rams, they both only deal half damage to each other. If a ramming ship is more than one location wide and rams a ship more than one location wide or long, both ship’s suffer ramming damage in every location struck by the other ship.

Called Shot (-2): When firing weapons at a ship, it is possible to make a Called Shot, firing not just at a location, but at an individual Hardpoint/Deck. This becomes an especially useful tactic when targeting a vehicle’s engine, sails, or attempting to blow a hole in their cargo bay to aid in boarding. Any damage dealt with a called shot is still subtracted from the location’s total HP (up to the total addition that Hardpoint or Deck made to the location’s total HP), but is also tracked separately as well. When a Hardpoint/Deck is reduced to 0 hp, it is destroyed and anything within that Deck or Hardpoint suffers all excess damage.

Flat-Hatting (-2): This is a dangerous manoeuvre, but it can save a pilot’s life. Flat-hatting is flying at high speed at barely above ground level. It requires a Piloting roll every round to avoid the various obstacles, including the Earth itself. Unless your opponent is also flat-hatting, you gain a minimum concealment of –2 and other aircraft must make a Notice roll each round to pick out your position.

Perch (-1): Most air combat takes place on generally the same level as the pilots jockey so one does not get the height advantage. By using this manoeuvre and getting a raise on an opposed Piloting roll, a pilot can get that height advantage on his opponent. This gives the pilot a +2 bonus to attack rolls. Unlike Tail (below), the pilot must get a raise on his Piloting roll each round to maintain the advantage.

Tail (0): The pilot must move into a square adjacent to another plane and then makes an opposed Piloting roll with the other pilot. If the initiating pilot can get a raise, they are considered tailing the other plane. The tailing plane moves with the other plane and gains a +2 bonus to attack rolls. It is impossible for a slower plane to tail a faster plane for more than one round.

Shake a Tail (0): A pilot that is being tailed can attempt to lose his pursuer. This is a simple opposed Piloting roll, only the tailing plane gets a +2 bonus. If successful, the plane takes its movement, leaving the tail behind. With a raise, the pilot can choose to reverse positions, and tail his old pursuer. If the tailed plane has a lower stall speed that his pursuer, the pilot gains the difference as a bonus to his Piloting roll.

Rolling: Sometimes, when a pilot attempts a sharp turn unsuccessfully, they can cause their plane to roll in the air. When a vehicle begins to roll, every creature aboard must pass a DEX save to secure themselves, or slide off the end of the vehicle, falling to the ground below. If a target is tethered to the vehicle they fall prone if they fail this check, but otherwise do not slide off. When a vehicle begins to roll, the pilot has one round to attempt to correct the vehicle with a piloting check. If they fail (or if they are unable to make this check), then the next round the vehicle turns completely upside down; all targets still aboard the vehicle must pass another DEX save to hold on tightly, or be dropped to the ground below. At this point, the pilot must pass a piloting check to correct the vehicle. If they fail or are unable to make this check, the vehicle stalls.

Uncontrolled
When a vehicle has no pilot, or the pilot is unable to control the vehicle’s movements for one reason or another, the vehicle is considered ‘uncontrolled’. An uncontrolled vehicle can only move forward at its current speed and if uncontrolled for more than 1 round, has a 20% cumulative chance per additional round that it will begin to roll.
1-2 Drop: The aircraft loses altitude. If your opponent did not have it before, they are now treated as having the Perch manoeuvre on you. If you were Flat-Hatting, you just met an immovable object, the Earth.
3-4 Shimmy: The aircraft begins to shake making it harder to control. –2 to Piloting rolls for D6 rounds.
5-9 Jerk: The aircraft makes a sudden movement in an unexpected direction. Move the aircraft D6 metres to either the right or the left (in the direction of the failed manoeuvre or away from the attack).
10-11 Spin: The aircraft goes into a spin. Each following round the pilot must make a Piloting roll; it takes a raise to pull out of a spin. If the aircraft does not pull out of the spin in 2D6 rounds, it collides with the earth.
12 Auger In: This is similar to a Spin, only the engine gets jammed at full throttle, pulling you to the ground. The same rules as a Spin apply except the Piloting roll is at –2, and the pilot only has D6+1 rounds before he hits the earth.

Aircraft Random Damage Table
Anytime a shot on a craft penetrates its armour, either by a roll over the vehicle's AC or when the HPs have been depleted, there is a chance that the vehicle may be crippled by the damage.
01-05 Control Mechanism Shot Out - –2 to all further Piloting rolls.
06-08 Landing Mechanism Shot Out.
09-12 Streamlining is Warped - Air resistance drops A/Df by 1.
13-15 Hole in Cooling System - Over the next 6 melees the engine will get hotter and hotter. After that. there's a 20% chance every melee that the engine will suddenly stop. Steam pours out from under the hood.
16-20 Weapon Systems Out - One of the weapons won't work. Reduce available ammunition by half, rounded down.
21-25 Electrical System Damaged - Control panel inside the crew compartment catches on fire. All flying is blind until the fire is put out. All Pilot Rolls are at a penalty of -3.
26-30 Pilot Controls Damaged - MR drops 1.
31-50 Cosmetic Damage - Vehicle loses chrome, paint and trim. Looks bad, but no real damage.
51-60 Navigation Equipment Destroyed- All further navigation must be done by dead reckoning. Navigator takes a penalty of -3 on all further rolls.
61-65 Exterior Electronics Disabled - Any electronic devices on the outside of tile vehicle are destroyed. Includes radar and radio antenna.
66-70 Battery Destroyed - Not a problem right away, but the vehicle can't he started again without a jump or replacement.
71-75 Alternator/Generator Wrecked - The vehicle stops recharging itself and is running off battery power alone. Will work for 3D6 melee rounds before draining the battery. then it'll quit.
76-85 Stall - Engine linkage temporarily disturbed. Pilot can roll under skill (without Air-to-Air bonus) on to restart. Can try once every Melee Round. Speed is halved.
86-90 The shot hit the pilot (or other passenger if more than one, determine randomly). Reroll damage from the attack and apply it to the character. They do get the benefit of the aircraft’s armour.
91-00 Wrecked - The attack ignites a fuel tank or other critical component. The pilot must make an DEX roll at –2 to parachute out.

Emergency Landings
When an aircraft conks out the pilot can attempt an Emergency Landing. This is done by rolling under the Pilot Skill (without Air-to-Air added in). The following penalties apply;
-3 for Helicopters
-1 for Jets
-1 if the vehicle was hovering
-2 if the vehicle was travelling over 1100kph
Failing the roll still means that the vehicle crashes, but speed is reduced to only a third of it's previous speed.

On Fire
A fire on a vehicle is a dangerous thing, more so than almost any other danger as it can quickly spread and consume it. When an attack causes a location to catch fire, every round it deals damage equal to its size to that location. The fire deals damage equal to its size each round, and increases its size by D6 each round (a 3D6 fire becomes a 4D6 fire the next round, then a 5D6 fire, etc.). If a fire ever reaches 10D6, it also spreads to all adjacent locations, which begin at F6 and increase as usual (if a secondary fire in an adjacent location is put out, but the original fire is still at 10D6 or higher, it will rekindle the fire in the adjacent location the next round, reset back at D6). There are three ways to put a fire out: a crew can put the fire out, a magic user can attacks the fire with magic, or the location can simply burn up; if a location is reduced to 0 hp, the fire instead deals damage to anything within that location. If nothing is within that location, the fire dies due to a lack of fuel. To put a fire out, a character must spend a standard action to actively attempt to control the fire with blankets, a fire pump, or whatever else is on-hand. Alternately, if a character has access to area-affect frost/water magic (such as ice storm, or an explosive orb frost blast), they may attempt to put the fire out that way. For every 10 points of damage dealt to the fire, the fire is reduced by D6 (however, no matter how small the fire is, it will continue to grow by D6 each round until extinguished).

The Skyreavers

The Throne of Clouds

Deflection Aerokinetic

Emission Aerokinetic

Emission Aerokinetic II

Emission Aerokinetic Bomb

Emission Aerokinetic Cage

Emission Aerokinetic Net

Field Aerokinetic

Field Aerokinetic II

Flight Aerokinetic

Infuse Weapon Aerokinetic

Manipulate Clouds

Manipulate Weather