(vis a vis suggested AA587 causes described here)

-----Original Message-----
From: Raymond Hudson [mailto:Rainman@tree-o-life.org]
Sent: Saturday, February 01, 2003 11:13 AM
To: safety@iasa-intl.com; 'David P Evans'
Subject: Re: For review

This whole investigation continues to give me a bad taste in my mouth about the ethical state of the agencies charged with ensuring air safety!

I will again point out that the evaluation of the A300-600's sensitivity of its FAC (yaw damper and rudder limiter) to ANY noise in air data (dynamic pressure) in the presences of an oscillatory yaw rate feedback (wake turbulence forcing function) is an elementary test to perform.  ANY hardware-in-the-loop simulator (i.e. real FACs with Level 4 flying qualities aerodynamic simulations) is capable of performing a closed-loop frequency response plot (Gain and Phase vs. Input Signal Frequency) that would answer the question once and for all if the "spiky" air data can cause a dynamic instability (phase reversal).

Those tests, and the result frequency response plots, would exhibit the GAIN MARGIN and PHASE MARGIN of the closed loop control system with respect to the driving parameters (yaw rate and dynamic pressure).  These plots tell the whole story.

If there were more experienced control systems engineers who attended the NTSB "sunshine" hearings, and DEMANDED (as a member of the taxpaying public) such data, the NTSB would be hard-pressed to continue its cover-up of these sorts of issues.

Indeed, democratic governments are only as good as the "intelligent" citizens that press their government agencies to perform their tasks in an adequate and thorough manner.

Rainman