In my "Glazed and Confused" presentation on "Glass Cockpits" I say that flying an aircraft with a non-certified, non TSO'ed glass standby (Dynon et al) is like jumping out of an airplane with only your main parachute and your standby plan is the fact you are wearing real soft socks.

Jeff referred to one of my earlier posts where I said.

"Regarding the question of backup systems, the more isolated your backup is from your primary, the less likely they will both be killed by the same event. If you wanted to guard against one of the windows in your house from being shattered by a miscreant juvenile with a penchant for throwing rocks you probably wouldn't put a second pane of glass behind the first as a single litho-projectile would destroy both.

A spinning mass gyro is still the best standby for your EFIS system. They operate on different physics than the MEMS AHRS, they can, with internal or external battery, be independent of  ship's power, they are familiar to all pilots and they are a cheap way to have TSO'ed gyro instrumentation."

Here is the link for the full posting from the archives:

http://mail.lancaironline.net:81/lists/lml/Message/45144.html?Language=

Regards
Brent Regan