Simplified attempt to explain the NORMAL higher speed
(in relation to the ground !) at high altitude.
To be able to fly, an aircraft needs to let
a certain amount of air particles pass the wings, during a specific time period. So, it needs to travel at
a certain speed through the air.
The density of the air at a higher altitude is less. The AIR PARTICLES are at a GREATER DISTANCE from each other. This distance increases with altitude.
In other words: When you go higher, the PATH from one AIR PARTICLE to the next will be LARGER.
If the same aircraft (as above) would fly at a higher altitude, the aircraft needs to go, in the same time period, a larger distance to be able to pass the same amount of air particles.
The number of air particles that passes, is a measure for the (Indicated) Airspeed (IAS).
The IAS is measured by the pitot tube. The pitot tube 'eats' the air particles and sends 'the amount eaten' to the pointer of the Airspeed Indicator.
At high altitude, in the same time period, the tube needs to 'eat' exactly the same amount of air particles to keep the aircraft flying as it needs at sea level. So, in reality, it needs to go faster (in relation to the ground). But the
Indicated Airspeed will be the same . . .
The airport altitude is around 11.000 feet. The speed increase effect is, except for pilots doing this on a routine basis, way beyond what one would expect and quite significant.
Kind regards, learner . . .
