Originally Posted by
Airbubba
When the CVR was introduced to U.S. carriers in the 1960's the erase button was demanded by ALPA due to privacy concerns of the crews. Of course, ALPA received assurances that the new CVR technology would only be used to improve safety and never for disciplinary or liability purposes.
The old CVR's recorded 30 minutes and the erase button cleared the whole recording. I believe on the 727 the parking brake had to be set and the engines shut down (or was it on external power?).
My recollection was setting the parking brake. The 727 wasn't on external power unless the APU was inop.
Ironically, to me anyway, current U.S. regs say the erase button can delete all but the last 30 minutes of the recording at any time, not just on the blocks:
Camels and tents.
A trend in recent years is for the NTSB to harvest what used to be labeled 'non-pertinent conversation' from the CVR. In the Colgan 3402 mishap a decade ago comments on commuting and sleeping in the crew lounge were included in the CVR transcript and even read into the Congressional Record.
It has morphed significantly, as do most things involving government.