Originally Posted by
bobusse
The need for a STAND-BY position on the switch is/was needed to keep the filament of the transmitting vacuum valve hot in case of immediate need(filaments could take up to a minut to be ready).
In the nowadays all solid state technology, is it still the case,if not,why to keep this position,rather confusing.
Since this equipment is essential for security,how about a condition to allow ,in flight of course,only momentary OFF push button which would restore itself to ON after a timed delay.
Good thought, Bobusse. Standby (or off) mode is needed while the aircraft is at the gate, at least. It has been pretty much agreed there was a failure in the Legacy transponder or its control. Would a self-reverting mode change remove a potential failure, or just add one more layer of confusion? Pilots are not comfortable with uncommanded mode selections or reversions.
Another option would be to trip the Master Caution system when transponder goes to Standby in flight. Whatever, this accident may well cause some change in all flight decks.
GB