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Pilot caused airport collision. NTSB report

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Pilot caused airport collision. NTSB report

Old 4th May 2007, 05:32
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Pilot caused airport collision. NTSB report

"A Northwest Airlines pilot's decision to shut down an engine, combined with a hydraulic problem, caused the May 2005 ground collision of two Northwest jets at the Minneapolis-St. Paul International Airport, federal investigators have concluded.
The Boeing DC-9 pilot's action just after landing in the Twin Cities meant that the plane lost all power to its steering, brakes and thrust reversers, causing it to strike an Airbus A319 that was being pushed back from a gate, according to a report issued last week by the National Transportation Safety Board.
The report detailed the events leading up to the accident and the investigation.
The DC-9, with 94 passengers on board, experienced problems with its right-side hydraulic system that powers its steering and brakes soon after leaving Columbus, Ohio. The captain decided to continue flying and declared an emergency as the plane neared the Twin Cities' airport.
After landing, the captain shut down the left engine, which powered the only fully functioning hydraulic system. As a result, the flight crew couldn't steer the plane or use the brakes and thrust reversers. The DC-9 hit a wing of the A319, with 38 passengers aboard, damaging the DC-9's cockpit and spilling fuel. Both planes were evacuated. The DC-9 pilot was seriously injured and seven passengers and crewmembers from both planes had minor injuries.
The NTSB report cited a "fatigue fracture" of the DC-9's rudder shutoff valve, which caused the loss of right-side hydraulic pressure, as a contributing factor in the accident.
Since the accident, Northwest developed an inspection procedure for its fleet in which "any rudder shutoff valve found to have a crack indication was replaced prior to further flight," said company spokesman Roman Blahoski. He declined to comment on the NTSB report.
A spokesman for Air Line Pilots Association at Northwest said the union could not comment on the report.
The NTSB report noted that Northwest recorded 38 instances of DC-9 rudder shutoff-valve housing failures from May 2000 to April 2005. "Northwest reported that they were aware of the cracked valve housings of the rudder shutoff valve prior to the accident" and after a 2003 analysis, according to the report. "The failure of the valve by itself was not determined to be a safety of flight issue and was therefore deemed solely a reliability issue."
After the accident, Boeing issued a "service letter" regarding the replacement of rudder shutoff valves."
http://www.twincities.com/business/c...nclick_check=1
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Old 4th May 2007, 07:03
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Can anyone explain why the engine would be shut down taxiing in??
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Old 4th May 2007, 07:10
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Beancounter SOPs trying to save the cost of a thimble full of fuel?

An expensive way of saving money, as it turned out.
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Old 4th May 2007, 07:11
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As a mere cherokee driver I understand it is quite a regular proceedure to shut down one of multiple engines on the taxi in ... it is not usual to shut down the "wrong" engine, if you have a partial failure or if that engine is the only one which normally powers essential equipment.

It has (I beleive) been known to catch out the unwary (I could say complacent but should also say stressed) when moving from one model of a particular flying machine to another, when the systems on the two models are powered from different engines.

BM 737-400 at Kegworth is one that sadly comes to mind.

DGG
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Old 4th May 2007, 07:21
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What would have happened had he had to shut down that engine prior to landing?
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Old 4th May 2007, 09:11
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There was video of this on the original thread of this accident/incident. Anyone still got it?
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Old 4th May 2007, 09:55
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Video at http://www.kstp.com/article/stories/s17479.shtml
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Old 4th May 2007, 12:39
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Can't access the NTSB site at the mo...

But, here is more detailed version of what occured:


Two Northwest Airlines planes collided on the ground in 2005 after thrust reversers failed, in effect meaning the pilot was unknowingly hitting the gas instead of the brakes, according to a recent report by the National Transportation Safety Board.
The collision between a DC-9 with hydraulic problems and a parked Airbus didn't kill anyone, but it was widely considered a very close call. Jet fuel poured into the demolished cocpit of the DC-9, soaking the seriously injured pilot, and both planes had to be evacuated.
The NTSB report issued late last month describes a series of hydraulic mishaps with flight 1495 from Columbus, Ohio, to Minneapolis.
One of the plane's two hydraulic systems failed in flight. That by itself wouldn't have been a huge problem, but after landing the crew shut down one engine, a common fuel-saving practice. That turned out to be the engine that powered the only hydraulic system that still worked.
Without hydraulics, the pilots couldn't steer, brake, or use thrust reversers. The NTSB cited the engine shutdown as the main cause of the crash, with the initial hydraulic failure as a contributing factor.
Knowing the plane had hydraulic problems, the captain declared an emergency before landing in Minneapolis, and the airport stationed firetrucks near the runway. But after a normal landing the DC-9 with 94 passengers taxied off the runway, and the firetrucks were sent back.
At some point as it taxied away from the runway, the left engine was shut down. As they turned into the gate area, the nose wheel steering failed.
When the captain said he couldn't steer, the co-pilot thought he was kidding, and laughed, according to the transcript of their conversation included in the NTSB report.
To keep the plane from rolling they applied the brakes, then asked to be towed to the gate. About a minute later, the brakes failed, too. The pilot turned on the thrust reversers, a device on the back of the jet engines that diverts their thrust forward, pushing the plane backward. That held the plane in place while the crew waited to be towed.
"Try the brakes. It's s-scary," the captain said to his co-pilot three minutes later, while they waited.
A minute later, still waiting for a tow, the captain said, "You know what? I coulda lost my reversers. We coulda gone right into that airplane."
Just over a minute later, that's exactly what happened.
The plane began to roll forward, slowly at first. The captain turned on the reverse thrusters—which had worked during the landing. They weren't working now. Instead the extra power made the plane move faster, without brakes or steering.
Perhaps seeing the plane moving again, ground control came over the radio: "Got your problem worked out?"
Nine seconds later the front of the DC-9 barreled into the wing of the Airbus at about 16 mph, the NTSB estimated. "The cockpit imploded and glass came flying in," the report says.
The captain felt jet fuel pouring on him. Through a hole in the wreckage between him and the co-pilot, he could see the co-pilot opening a cockpit window and believed he was getting out of the plane that way. The captain eventually wriggled through the demolished cockpit and out into the cabin, which had already been evacuated.
A ground worker banged away on a cockpit window with a fire ax to free the co-pilot, unsuccessfully. He got out a few minutes later through the back of the cockpit.
The Northwest Branch of the Air Line Pilots Association said it had no comment on the NTSB report.
The NTSB said the initial hydraulic problem was caused by a worn-out shutoff valve. Northwest Airlines Corp. spokesman Bill Mellon said the airline inspected those valves on all its planes and replaced all that showed any sign of cracking.
http://www.twincities.com/localnews/ci_5801459
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Old 4th May 2007, 12:46
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Full narrative

Boeing DC-9
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Old 4th May 2007, 12:47
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But if it was a new one it'd be a Boeing 717

http://www.boeing.com/commercial/717/index.html

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Old 4th May 2007, 13:40
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as boeing bought douglas, the DC9 is now a boeing plane.

stupid, but true.

if one had shut down the right engine in flight in this case, the flight would have landed safely, free fall the gear, stop on the runway hopefully the accumulators would have worked for brakes and thrust reversers. don't know why they didn't work later on unless other factors present
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Old 4th May 2007, 13:43
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ok, if the thrust reversers had been deployed once, the accumulators might not have been able to do it again.

should have stopped, set parking brake and waited...then shut down both engines, leaving APU on and auxilary hydraulic pump (*electrically powered).
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Old 4th May 2007, 13:49
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this accident shows a funamental misunderstanding of the dc9 hydraulic system.

of ANY jet transport, the dc9 is the easiest to handle in a full loss of all hydraulic pumps...but once on the ground, stop and don't move.

full basic flight controls manual reversion, free fall gear, accumulators for brakes and thrust reversers
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Old 4th May 2007, 15:14
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Can anyone explain why the engine would be shut down taxiing in??
Saving gas is one answer. I agree that it's a questionable tradeoff in a lot of cases.

Another reason for single engine taxi is that many twins are overpowered in taxi with a light aircraft (and even more so in cool weather).

There is a classic trap involving single engine taxi and the takeoff warning horn. If you're in single engine taxi and stop the aircraft, you sometimes need a throttle setting that will blow the takeoff warning horn to resume taxi. Years ago the common remedy was to pull the takeoff warning horn circuit breaker. Inevitably, the breaker would be forgotten, sometimes with disastrous results.

Here's one example:

http://www.flight255memorial.com/thecrash.html
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Old 5th May 2007, 03:23
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This is the danger of a relatively innocuous SOP (closing down an engine for taxying) becoming more compelling than applying Airmanship based on aircraft systems knowledge. Since we don't have a sharp eyed FE anymore, it is paramount that somebody up front has the requisite systems knowledge other than the computers. Similar from a Human Factors (Aircrew) perspective to the Qantas 747 in the far east that overran the runway in a Cyclone, because the Captain did not use full flap and landed fast on a wet and windy runway, because he adhered to a company SOP designed to avoid high power settings on finals, rather than do what his experience and instinct would have told him to do.
Aviate - Navigate - Communicate, even when on the ground.
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Old 5th May 2007, 11:51
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It's the Communicate part that was sadly lacking. Maintenance was on board the "yellow emergency" while the plane was still airborne, and should have been aware of the peril of shutting down (or losing) an engine, even if it wasn't obvious to the cockpit.

An aircrew needs sound technical backup, if not in the third seat, then on the company frequency. It would be interesting to see the internal NWA ramifications of this failure to COMMUNICATE.
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Old 5th May 2007, 14:08
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Quote: The DC-9 pilot was seriously injured

Anyone know how the captain is doing, and if he's flying again??
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Old 7th May 2007, 16:56
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Well our B737 FCTM says don't taxi with one engine, but I see guys (mainly from Nth America) doing it, and I can't see how the benefits can possibly outway the negatives. To extrapolate; many years ago in an Indonesian carrier, they used to shut down both engines and "glide" into the gate. It would have been fun to subteley apply the brakes from the right seat prior to arrival at the gate.
If only I new then what I know now
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Old 8th May 2007, 01:01
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The horrible thing is that they had it stopped and contained...for a moment anyway.

From the dialog, I wouldn't be surprised if the captain was using up valuable hydraulic reserves while telling P2 about how the brakes feel.

This really spells it out about knowing your systems.
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Old 8th May 2007, 07:26
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I've just watched the video of the incident via the link posted above - wouldn't this incident be a great example to all those bloody impatient SLF who insist on removing their belts, standing up and retrieving their all so important belongings from the overhead bin before the ride has come to a complete halt??
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