Can't catch me..

[LastMinute]

GPS is 3 dimensional AFAIK

You could say it's 4-dimensional, because GPS position is a function of time.

so altitude should be factored into the speed reading.

Altitude (strictly "GPS height") is not a factor in ground speed.

was curious what the take-off speed of a BAe146 was once

But you were measuring ground speed; an aeroplane takes off at a given air speed.

 

[smartbrabus]

You could say it's 4-dimensional, because GPS position is a function of time.


Altitude (strictly "GPS height") is not a factor in ground speed.


But you were measuring ground speed; an aeroplane takes off at a given air speed.

Indeed - I'm aware I was measuring ground speed! Just confirming that its possible and not that difficult to get a GPS signal from inside an aircraft