Expert: Paul Soderman - 5/25/2003

Question
Dear sir,
How do pilots know of an incoming turbulent air?  What instruments detect these signs? Can you explain it in Physics?  I am a freshman engineering student here in California.  We discussed a little bit about Reynolds number, bernoullis equation in my engineering physics class (Mechanics for engineering majors).  Thank you very much.

Bryan Catacata
vindicate@msn.com


Answer
That is a very good question Bryan.  NASA has been trying to figure this one out for some time.  Radar, laser devices, acoustic devices - nothing has proven to be reliable or easy.  So, currently, pilots cannot detect turbulent air.  But from experience, they know that contrails in their flight path or certain weather conditions such as thunder heads are good indicators of turbulent conditions.  They can even judge if they are going to pass the wake of another aircraft, which can also be very turbulent.  But I know of no flight worthy turbulence detector, thought their are probably research efforts ongoing to find such a device.    At airports, people have had some success with tracking vortices using radar or acoustic devices that record a disturbance in the received signal such as a Doppler shift or refraction or a wave.  Vortices are often audible and might be trackable with an acoustic antenna.  But to get a return signal to an aircraft in flight would be difficult.  Good luck with your studies.
Paul