"Faulty speed readings and electronic failures were cited by crash investigators yesterday as they said they were closer to understanding the loss of Air France Flight 447 on June 1, with the deaths of all 228 people on board."

As the above news report states,some jet airliners may have faulty electronics that fail to indicate the accurate speed at which an airplane is actually travelling.Maybe this faulty instrument speed reading could be checked against a reading of the airplane's Global Positioning Satellite system readings? The distance an airplane is travelling between two points,as indicated on its GPS could easily be calculated to show the airplane's actual air speed between those two points! Pilots could take a GPS reading on their present location in reference to another previous GPS location at different time intervals from one minute to one hour etc. to calculate just how fast the aircraft is travelling between those two points.This data of course would be calculated a computer program or even by the manual use of a calculator by the pilots.It would be just one more safety tool to help pilots determine the actual speed at which they are travelling no matter what the outside conditions are!

What aircraft instruments measure using the pitot/static ports is the plane's velocity relative to the air around it. This is what a pilot needs to know how close to stalling the wings are, whether it's safe to maneuver, when the plane is going fast enough on its takeoff run to rotate and so on.

Ground speed, which is important primarily for figuring out where the Hell you are in relation to the Earth's surface, is the vector sum of airspeed and wind velocity at the altitude where the plane is flying.

GPS measurements of ground speed, which is what you would get using GPS, would not be terribly useful for flying the plane.

It's a neat idea, though. Kudos for thinking outside the box, but the Devil really is in the details.

The comment about airspedd Vs ground speed is valid , however GPS speed checking would be a method of validating the air speed reported by the pitot system and would at least indicate that you were going forward and not standing still horizontally while moving very quickly vertically as appears to have happened to the Air France aircraft. I am puzzeld as to what was happening on the altitude indicator. Is this not a barometirc reading seperate from the Pitot system. Could the altitude not also be calculated by GPS and used as a backup to the barometric altitude system?

"North Tinian tower,this is Dimples 8-2 requesting taxi clearance"

~Col Paul Tibbets~

Aug, 6 1945