Standby Instrument
Being one of the "seven or so" crews referred to earlier on who managed to get the Battery Master off instead of the Battery Main while dealing with Double DC Gen failure in the Sim, I can attest to the thoroughly unpleasant sinking feeling when everything, and I mean EVERYTHING in front of you goes black!
From initial Ground School, I've had some personal reservations about the lack of an independent power supply for that instrument. It does seem extraordinary that a perfectly simple mistake - two adjoining switches with broadly the same function in principle - can result in a blackout. If it happens IMC, no screens and no APs means you're headed for the obituary columns.
However, an independent supply for the instrument might only provide attitude reference and, presumably airspeed and altitude information (yes, I appreciate that's all it takes to stay alive) with all the other information normally available coming from NAV sources which depend upon power from the primary electrical system being lost. Don't know how it might be designed to work in practice.
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Last edited by heliski22; 11th June 2008 at 11:22.