Standardization of audio controls
Some guys on the line can't comment for obvious reasons.
Question to retired guys:
High altitude 747 t/o's are essentially semi-unpressurized, packs off, (which is different than some jets that allow a pack to run at t/o on apu, IIRC
I can't get to my books out here, but I seem to remember a high altitude procedure & charts where all bleeds are kept off until clean up. This ensures extra power for first, second, and final segment climb capabilities.
Operational profiles are different at different carriers but, we used to typically call for climb power at 1500ft AGL and then level off to accelerate at 3000 feet AGL. After flps 1 call, IIRC, the bleeds would be re-opened as to provide PDU function for the slats retract call typically at around 220kts according to weight.
Bogota's 8400 ft field elevation plus 3K equals 11,400 meaning a cabin altitude warning horn would go off at cabin altitude of before 10K, right? Did you don masks before t/o?
We have a second-hand report from a cab driver that the crew were wearing Oxygen Masks when found. My reason for focusing on this is that we had at least five different types of audio selector in our fleet of 747's when I flew it. It was not a simple thing in the dark to don the mask and wrestle with a dirty, poorly lit, confusing unit that was different than the simulator. Some you flipped a switch, others you flipped two switches, some you lifted and turned a knob and flipped a switch, some you depressed a button and turned two knobs .... and if you didn't get the speaker volume and selector volume up, you just wasted your time and had to start over again. I just can't see how anybody could do a good job navigating or communicating with this damn impediment in play.
Back before de-regulation, carriers had the money and the safety culture to attempt to standardize fleet cockpits. Not saying that this had anything to do with the Bogota accident. But this could have been a factor. JMHO's only.
It's clear to me at least, that deregulation of airlines, banks and oil just hasn't worked out at all!
pac
Last edited by pacplyer; 13th Jul 2008 at 04:55.
Reason: unpressurized comment correction, high alt comment