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Started By
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Scandanavian Airlines Flght 551 12/27/91 Land based version of Sully
Posted on 11/13/19 at 9:02 am
Posted on 11/13/19 at 9:02 am
MD-81 with 123 passengers takes off from Stockholm. On climb out, the engines start making "banging" sounds, and then fail. Engine restarts do not work. Captain Rassmussen and crew land the plane in the woods near a clearing (the plane ends up in the clearing) and everyone survives (only 25 were injured, two seriously).
When preparing the plane on the ground, the airline's icing crew did not see some clear ice at the rear of the wings, and in flight the ice broke off into the engines. The crew properly reduced power when the engines acted up, but the airline had put in a system that would automatically increase power during a climb if the pilots reduced power. The power increase destroyed both engines.
The kicker: The airline didn't tell the pilots about the system.
The Captain who handled the miraculous landing never flew again.
Nice short re-enactment of the crash:
Flight 751
When preparing the plane on the ground, the airline's icing crew did not see some clear ice at the rear of the wings, and in flight the ice broke off into the engines. The crew properly reduced power when the engines acted up, but the airline had put in a system that would automatically increase power during a climb if the pilots reduced power. The power increase destroyed both engines.
The kicker: The airline didn't tell the pilots about the system.
The Captain who handled the miraculous landing never flew again.
Nice short re-enactment of the crash:
Flight 751
3
Posted on 11/13/19 at 9:08 am to chinhoyang
quote:
but the airline had put in a system that would automatically increase power during a climb if the pilots reduced power. The power increase destroyed both engines.
quote:
The airline didn't tell the pilots about the system.
having to call bs on this chin, you trying to start a Max conspiracy?
the JT8D-200 on the mad dog does have an automatic reserve thrust system on it that can be disarmed but it's not going to just "fire off," I'll have to look this one up
Posted on 11/13/19 at 9:09 am to chinhoyang
Nvm.
I don't read good
I don't read good
This post was edited on 11/13/19 at 9:10 am
Posted on 11/13/19 at 9:13 am to 777Tiger
The report:
"The accident was caused by SAS's instructions and routines being inadequate to ensure that clear ice was removed from the wings of the aircraft prior to takeoff. Hence the aircraft took off with clear ice on the wings. In connection to lift-off, the clear ice disengaged and was ingested by the engines. The ice caused damage to the engine fan stages, which led to engine surges, and these triggered irreparable engine failure. The pilots were not trained to identify and eliminate engine surging; furthermore, the Automatic Thrust Restoration system was not known by the pilots, nor noticed by the airline."
"With sufficiently reduced thrust in the right engine and maintained thrust (not increased) in the left engine, the engines would probably not have failed. The aircraft would then have been able to return for landing."
However, the newly installed ATR prevented the pilots from successfully performing the normal remedial measure to halt compressor stall, i.e., throttling back the engines, as the ATR system – designed to prevent pilots using less than normal thrust when climbing out after take-off for noise abatement reasons – restored engine take-off power throttle settings contrary to the pilots' reduced throttle commands. This damaged the engines, until eventually, they failed completely.
"The accident was caused by SAS's instructions and routines being inadequate to ensure that clear ice was removed from the wings of the aircraft prior to takeoff. Hence the aircraft took off with clear ice on the wings. In connection to lift-off, the clear ice disengaged and was ingested by the engines. The ice caused damage to the engine fan stages, which led to engine surges, and these triggered irreparable engine failure. The pilots were not trained to identify and eliminate engine surging; furthermore, the Automatic Thrust Restoration system was not known by the pilots, nor noticed by the airline."
"With sufficiently reduced thrust in the right engine and maintained thrust (not increased) in the left engine, the engines would probably not have failed. The aircraft would then have been able to return for landing."
However, the newly installed ATR prevented the pilots from successfully performing the normal remedial measure to halt compressor stall, i.e., throttling back the engines, as the ATR system – designed to prevent pilots using less than normal thrust when climbing out after take-off for noise abatement reasons – restored engine take-off power throttle settings contrary to the pilots' reduced throttle commands. This damaged the engines, until eventually, they failed completely.
Posted on 11/13/19 at 9:26 am to chinhoyang
quote:
The report:
I've got about a thousand hours operating that engine, my company used to have the worlds largest fleet of MD-80s, the ART system is not a custom "option" nor add-on, it came with the jet, it doesn't have to be armed or operable for every flight, all it does when armed, is open a fuel solenoid when the dgfc senses an engine failure(roughly 30% split in N1s and one engine pushed up to greater than roughly 80%,) and increase thrust on the good engine by about 800-850lbs., doesn't mean the pilot doesn't have control over it either, if it activated all he had to do was grab the thrust lever and either pull it back or disconnect it
Posted on 11/13/19 at 9:28 am to 777Tiger
Posted on 11/13/19 at 9:35 am to 777Tiger
quote:
the JT8D-200 on the mad dog does have an automatic reserve thrust system on it that can be disarmed but it's not going to just "fire off," I'll have to look this one up
Why do manufacturers not create an alert when the computer is overriding pilot input?
The control systems have all sorts of automated verbal cues, why can't they just add one saying, "MCAS detects stall threat, pitching nose down"
Or in the case above "Automatic thrust system ACTIVE"
Posted on 11/13/19 at 9:37 am to Tigeralum2008
quote:
Why do manufacturers not create an alert when the computer is overriding pilot input?
well, you should actually know a little bit about your jet before just strapping it on and going for a spin
ETA: there is a light in the cockpit that tells you that the ARTS has activated, btw, because the thrust lever doesn't physically move, pretty old technology
This post was edited on 11/13/19 at 9:44 am
Posted on 11/13/19 at 9:45 am to 777Tiger
The report states that the ATR was installed by the airline in response to pilots reducing thrust on takeoff to reduce noise.
Posted on 11/13/19 at 9:49 am to chinhoyang
quote:
The report states that the ATR was installed by the airline in response to pilots reducing thrust on takeoff to reduce noise.
I'm not being condescending, at all, but that's not how this works, that's not how any of this works
at certain noise sensitive airports there are specific noise abatement procedures for particular runways, the procedures are aircraft specific and some require a thrust reduction at a non-standard point in the climb profile, I think something was lost in translation between the accident report and the steno that wrote that up
ETA: ARTS is just a safety barrier that only would activate at the loss of an engine at a critical phase of flight, i.e. takeoff, and as previously mentioned, it requires a failure of one engine and a high power setting on the other engine
This post was edited on 11/13/19 at 9:52 am
Posted on 11/13/19 at 3:02 pm to 777Tiger
quote:
I'm not being condescending, at all,
I know you weren't. I posted my response hoping for more information from you.
Posted on 11/13/19 at 3:09 pm to chinhoyang
quote:
I know you weren't.
one of the few things I'm familiar with, and don't know why I remembered that because it's been 26 years since I flew that thing
Posted on 11/13/19 at 3:10 pm to 777Tiger
quote:
777Tiger
Are you a commercial pilot only, or past military?
Posted on 11/13/19 at 4:39 pm to chinhoyang
Fun Fact:
SAS hands down has the best stewardesses with Aeroflot a close second.
SAS hands down has the best stewardesses with Aeroflot a close second.
Posted on 11/13/19 at 4:47 pm to MojoGuyPan
Meanwhile in the US;
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