Mach Number - M. The Mach Number, , is the ratio of the aircraft's true air speed (TAS or va) , and the local velocity of sound vs.
The velocity of sound (to first order, ) depends only on the static air temperature :o(Ts), where R is the Gas Constant, R , which for dry air is 287.053 J kg-1 K -1 and is the ratio of the specific heats at constant pressure and volume.
Temperature
Air density decreases with altitude. At high elevation airports, an airplane requires more runway to take off
. Its rate of climb will be less,
its approach will be faster,
because the true air speed [TAS] will be faster than the indicated air speed [IAS] and the landing roll will be longer :(
Air density also decreases with temperature. Warm air is less dense than cold air because there are fewer air molecules in a given volume of warm air than in the same volume of cooler air. As a result, on a hot day, an airplane will require more runway to take off, will have a poor rate of climb and a faster approach and will experience a longer landing roll.
In combination, high and hot, a situation exists that can well be disastrous for an unsuspecting, or more accurately, an uninformed pilot. The combination of high temperature and high elevation produces a situation that aerodynamically reduces drastically the performance of the airplane. The horsepower out-put of the engines decrease because its fuel-air mixture is reduced. The propeller develops less thrust because the blades, as airfoils, are less efficient in the thin air. The wings develop less lift because the thin air exerts less force on the airfoils. As a result, the take-off distance is substantially increased, climb performance is substantially reduced and may, in extreme situations, be non-existent.
Mountain airports are particularly treacherous when temperatures are high, especially for a low performance airplane. The actual elevation of the airport may be near the operational ceiling of the airplane without the disadvantage of density altitude. Under some conditions, the airplane may not be able to lift out of ground effect :oor to maintain a rate of climb :onecessary to clear obstacles or surrounding terrain.
So in real life with real people yes you do have to firgure temperature fo take-off
But Flight simulator you don't have to worry about it 8)
So tell your passenger to sit down and sut up its time for take-off
Thunder storms produce your downdrafts so stay at least 20 miles or more away from them or you could see a big down draft and have a bad day
. There is a simple relationship between TAT (Tt), SAT (Ts) and Mach Number (M): 
