Originally Posted by
Sunamer
You can't get AoA or airspeed from INS.
surely, GPS is absolute and doesn't have to be integrated. Based on that you can even get GS, but airplane doesn't care about GS at all.
AoA vanes and pitot tubes are the only direct measurements of those crucial parameters that can be obtained.
What you say is true - as an instantaneous measurement. But if for a period of time I have ground speed and track from GPS and airspeed from a pitot tube then I can calculate the ambient windspeed and direction. If the pitot sensed airspeed drops out - I can generate and display an airspeed based on the ground speed from GPS and the previous windspeed and direction. In most cases this will be near enough to provide the pilot with sufficient useful information. Add the pilot selecting the appropriate 'pitch and power' for cruise to that and in most instances the information is sufficient to recover the aircraft. This is on the assumption that there will not be gross changes in wind speed/vector in the short period of time before the air driven sensors come back on line.