Vessbot:Turning around inside an airliner does not change your momentum with respect to the earth. It is still related to the vector of the aircraft. The only change you could make is to run from nose to tail down the aisle and then you would only reduce it by your running speed times your mass! A tiny reduction compared to the aircraft. This is the same fallacy about being in a runaway lift(elevator) where the occupants are asked to jump upwards just before impact with the bottom to save thenselves! Won't work.
Jet Fan: I think you are being ironic!!