Expert: Colin Woehrle - 5/30/2007

Question
Would it ever be possible for a commercial jet airliner to be able to fly off into space if the pilot kept flying the aircraft in a continual ascent?  Other than the lack of air/oxygen for ensuring the engines stayed alight, what else prevents this from happening?

Answer
Hi Graham,

This would not be possible due to the lack of air density at such high altitudes. Without adequate air density, the engines cannot provide sufficient thrust. Without sufficient thrust to propel the airliner through the air fast enough for the wings to produce enough lift the aircraft will reach it's absolute altitude (the altitude at which it's not possible to climb any higher) or stall.

To simplify, the air molecules are more spread out at higher altitudes and therefore the aircraft needs to travel faster through the air to produce lift. If the engines can only produce so much thrust at a given altitude due to lack of air density, then the aircraft true airspeed is limited as well and that will determine its maximum altitude.

Hope this makes sense. Thanks for the question Graham!

Colin