For example, a > (hypothetical!) button that shuts down the jet engines on an aircraft > requires a confirmation step... because turning off the engines until > the pilot hits UnDo would be bad! > > This rule applies to software as well as hardware. > > -- Eric K3NA This has no bearing on the current discussion but might be interesting to some. The "button that shuts down jet engines" is protected only by the human instinct to survive. We sit there for thousands of hours in the cockpit and never have any impulse to move those switches to the "cutoff" position, except during an intentional engine shutdown. (You usually have to lift and move to get to the cutoff position; you can't brush against them and move them.) I can only recall one case where a B767 pilot moved both switches to the cutoff position unintentionally. He thought they were something else I think. That event had a happy outcome. He did resort to an "undo" procedure.
Some airplanes with overhead panel pushbutton fire switches are guarded mechanically to avoid hitting them with your head or shoulder when you get out of your seat. (The fire switches cut off fuel to the engine, among other things.) Ed Lambert KD3Y (B747-400) _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
