Quote:
Originally Posted by ShyGuy
Correction............
"At a 4:15 p.m. briefing, Sumwalt also said that sounds "consistent with impact" are heard nine seconds before the end of the recording."
Then 9 seconds prior to end of recording is the first impact, which means it took 9 seconds from impact to power cutoff for CVR/FDR recording. A sink rate aural 16 seconds prior to end of recording means 7 seconds prior to the first impact.
That is correct. 7 seconds between "SINK RATE" and sounds of impact.
We do not know the RA height or the sink rate when that alert was sounded.
However, we DO know that, contrary to your earlier assertion, GPWS Mode 1 "SINK RATE" aural alert does not mean the "
descent rate would have had to been 2,000+ fpm". That's the only reason I posted earlier, and that's the part of your post I highlighted with bold font. The far end of the graph begins at 1,000 fpm and 30' RA.
At 1,100 fpm, the Mode 1 "SINK RATE" aural alert will sound at 90.5' RA.
At 1,100 fpm, the airplane will descend 128 feet in 7 seconds.
At 1,200 fpm, the Mode 1 "SINK RATE" aural alert will sound at 151' RA, and the airplane will descend 140 feet in 7 seconds.
The accident site terrain was sloped downward away from the direction of travel.
I'm not trying to suggest that I have any idea what altitude the airplane was at, or what its descent rate was. I AM averring that it did not have to be 2,000+ fpm to generate the "SINK RATE" alert.
Here's another interesting fact that you should notice and file away. Before I took a closer look at the graph a couple of months ago, I was under the impression that a "SINK RATE" aural alert would be followed by a "WHOOP-WHOOP, PULL UP" aural warning prior to ground impact. That is
not correct. The upper edge of the aural warning graph is not a straight line. At 284' RA and 1,700 fpm, it takes a different slope that ends at 30' RA and 1,500 fpm. Therefore, at sink rates between 1,000 fpm and 1,500 fpm, there will never be a "WHOOP-WHOOP, PULL UP." In that range of sink rates, the next thing you might hear after "SINK RATE", unless you do something to change the path of the airplane, is the sound of ground impact.
Sound familiar?
.