Dominican Air Charter B757
Ron Hepler
I'm new to this group, Sorry if I'm rehashing old issues.
Around the time of the AMR B757 crash in Columbia, a Dominican Air
Charter B757 crashed into the Carribien Sea shortly after take off, bound
for Frankfurt (I think). The oficial report was that it stalled at
an altitude of 7000 ft. after being slowed as a result of a defective
airspeed indicator.
Since it wasn't a US carrier details are sketchy. No recording of tower
communications have been released to my knowledge, kind of like that T-43
in Croatia.
A 757 Pilot tells me that the 757 has the highest thrust to weight ratio
of any commercial aircraft. he said that Stalls are a joke, firewall
thrust produces essentially no loss of altitude. Even without added
thrust, simply pushing the nose over produces recovery from an imminent
stall (buffetting & Stick Shaker) with little loss of altitude.
Additionally, the aircraft has a seperate airspeed indicator for the F.O.
& a third seperate backup.
There was a last minute equipment change, pulling the ill-fated aricraft
hastilly from maintenance.
My initial reaction at the time was missing oil plugs in the engines, but
surely that would have been factually reported. After the TWA 800
incident, this implausable story raises questions again.
Any thoughts?
Doug Haluza
On Oct 02, 1996 04:03:38 in article <Dominican Air Charter B757>, 'Ron
Hepler <rhe...@i-link.net>' wrote:
>Around the time of the AMR B757 crash in Columbia, a Dominican Air
>Charter B757 crashed into the Carribien Sea shortly after take off, bound
>for Frankfurt (I think). The oficial report was that it stalled at
>an altitude of 7000 ft. after being slowed as a result of a defective
>airspeed indicator.
This sounds like BS since any pilot worth his/her salt should be able to
tell the difference between climb airspeed and stall without an airspeed
indicator. Of course the airlines have been putting "systems managers"
rather than pilots up front, especially in glass cockpit birds like the
757.
>A 757 Pilot tells me that the 757 has the highest thrust to weight ratio
>of any commercial aircraft. he said that Stalls are a joke, firewall
>thrust produces essentially no loss of altitude. Even without added
>thrust, simply pushing the nose over produces recovery from an imminent
>stall (buffetting & Stick Shaker) with little loss of altitude.
>Additionally, the aircraft has a seperate airspeed indicator for the F.O.
>& a third seperate backup.
Actually the high thrust/weight ratio makes a stall more likely. Stalls are
caused by exceeding the critical angle of attack of the wing, regardless of
thrust or airspeed. Unless the thrust/weight ratio is greater than 1 (which
it isn't) the aircraft can still stall. The high climb angle possible with
relatively high thrust would reduce the visual cue of a nose high attitude
prior to a stall. I guess a 757 cockpit is pretty quiet, so there wouldn't
be much of an audible cue either. If the pilots beleived a faulty airspeed
indicator, they might have reacted with surprise to the stick shaker and
done something wrong.
"Simply pushing the nose over" does produce recovery from an imminent
stall. But stall/spin accidents continue to happen.
>Any thoughts?
That's my $0.02
--
Doug Haluza
ke...@tstonramp.com
Ron Hepler <rhe...@i-link.net> wrote:
>I'm new to this group, Sorry if I'm rehashing old issues.
>Around the time of the AMR B757 crash in Columbia, a Dominican Air
>Charter B757 crashed into the Carribien Sea shortly after take off, bound
>for Frankfurt (I think). The oficial report was that it stalled at
>an altitude of 7000 ft. after being slowed as a result of a defective
>airspeed indicator.
>Since it wasn't a US carrier details are sketchy. No recording of tower
>communications have been released to my knowledge, kind of like that T-43
>in Croatia.
>A 757 Pilot tells me that the 757 has the highest thrust to weight ratio
>of any commercial aircraft. he said that Stalls are a joke, firewall
>thrust produces essentially no loss of altitude. Even without added
>thrust, simply pushing the nose over produces recovery from an imminent
>stall (buffetting & Stick Shaker) with little loss of altitude.
>Additionally, the aircraft has a seperate airspeed indicator for the F.O.
>& a third seperate backup.
>There was a last minute equipment change, pulling the ill-fated aricraft
>hastilly from maintenance.
>My initial reaction at the time was missing oil plugs in the engines, but
>surely that would have been factually reported. After the TWA 800
>incident, this implausable story raises questions again.
>Any thoughts?
It is my understanding that the faulty air speed indicator caused the
autopilot and later the crew to reduce speed until the aircaft
stalled.
Neil D Robertson
In article <52tdfi$s...@news1.t1.usa.pipeline.com> dha...@nyc.pipeline.com(Doug Haluza) writes:
>From: dha...@nyc.pipeline.com(Doug Haluza)
>Subject: Re: Dominican Air Charter B757
>Date: 2 Oct 1996 09:43:14 GMT
>On Oct 02, 1996 04:03:38 in article <Dominican Air Charter B757>, 'Ron
>Hepler <rhe...@i-link.net>' wrote:
>
>>Around the time of the AMR B757 crash in Columbia, a Dominican Air
>>Charter B757 crashed into the Carribien Sea shortly after take off, bound
>>for Frankfurt (I think). The oficial report was that it stalled at
>>an altitude of 7000 ft. after being slowed as a result of a defective
>>airspeed indicator.
>
>This sounds like BS since any pilot worth his/her salt should be able to
>tell the difference between climb airspeed and stall without an airspeed
>indicator. Of course the airlines have been putting "systems managers"
>rather than pilots up front, especially in glass cockpit birds like the
>757.
>
>>A 757 Pilot tells me that the 757 has the highest thrust to weight ratio
>>of any commercial aircraft. he said that Stalls are a joke, firewall
>>thrust produces essentially no loss of altitude. Even without added
>>thrust, simply pushing the nose over produces recovery from an imminent
>>stall (buffetting & Stick Shaker) with little loss of altitude.
>>Additionally, the aircraft has a seperate airspeed indicator for the F.O.
>>& a third seperate backup.
>
>Actually the high thrust/weight ratio makes a stall more likely. Stalls are
>caused by exceeding the critical angle of attack of the wing, regardless of
>thrust or airspeed. Unless the thrust/weight ratio is greater than 1 (which
>it isn't) the aircraft can still stall. The high climb angle possible with
>relatively high thrust would reduce the visual cue of a nose high attitude
>prior to a stall. I guess a 757 cockpit is pretty quiet, so there wouldn't
>be much of an audible cue either. If the pilots beleived a faulty airspeed
>indicator, they might have reacted with surprise to the stick shaker and
>done something wrong.
>
>"Simply pushing the nose over" does produce recovery from an imminent
>stall. But stall/spin accidents continue to happen.
>
>>Any thoughts?
>
>That's my $0.02
>--
>
>Doug Haluza
The information that I have is that the Birgenair (a Turkish airline) Boeing
757 had stood unattended and -without- pitot covers. The Captain was aware
that his ASI was malfunctioning, and the CVR shows that they were using the
F/O's ASI for the speed call-offs.
However, what they had not done was to disable the input of the Captain's ASI
into the FMS, which led to the aircraft thinking that it was flying faster
than it was. The autopilot therefore throttled back and increased pitch, which
led to the stall.
The accident could have been avoided if:
1) The pitot covers had been put on the aircraft as part of the arrival checks
and the pitot heads checked when the aircraft was pre flighted;
2) The Captain had disabled his ASI input, switching instead over to the First
Officers'.
3) The autopilot had been disengaged as soon as the aircraft started to pitch.
4) The crew had applied full power (you can never have too much!)
I think that covers it. It will be very interesting to see what happened with
the AeroPeru 757!
Neil D Robertson
Chief Executive
Lionair Limited
Johannesburg, South Africa