Northwest Jet Suffers Similar Malfunctions to Air France Flight

Wall Street Journal ^ | 26 June 2009 | ANDY PASZTOR and DANIEL MICHAELS

[Erik Latranyi]

A Northwest Airlines jet traveling from Hong Kong to Tokyo last Tuesday suffered a series of equipment and computer malfunctions strikingly similar to those encountered by Air France Flight 447 just before it crashed into the Atlantic Ocean on May 31.

The Northwest plane and its passengers, however, emerged unscathed. Details of the harrowing incident – described in a memo by one of the Northwest pilots and confirmed Friday by others familiar with the matter – highlight how cockpit crews can safely cope with something that is almost never supposed to happen: a system breakdown that prevented the crew from knowing how fast the plane was flying.

During the brief but dramatic event, the Northwest Airbus A330's crew was left without reliable speed measurements for three minutes. In addition, the computer safeguards designed to keep the aircraft from flying dangerously too fast or too slow were also impaired. Like the Air France A330 jetliner, the Northwest plane entered a storm and quickly started showing erroneous and unreliable airspeed readings.

[safisoft]

"We had good conditions for the failure; daylight, we were rested, relatively small area, and light turbulence. I think it could have been much worse. Jerry did a great job flying and staying cool. We did our procedures called dispatch and maintenance on the SAT COM and landed in Narita. That's it."

In all of Airbus' history, aircraft have landing in direct law only a dozen times, and in alternate law only a dozen times a year. It does happen, which is why there are three design redundancies in flight laws. This event resulted in a single redudancy being lost, and a remaining direct law redundancy. The airline I fly for, we train for EXACTLY this scenario, and the results when they happen (you don't read about it because it is not newsworthy), our crews follow procedure and we have similar results. Crew training is what makes all the difference.

[gusopol3]

I’ve driven a car with a broken speedometer

that I've done; now have you ever driven a stick shift with the throttle jammed wide open by switching off the engine at stop lights?

[Vaduz]

Heat kills electrical circuits FAIL ever notice the cases of smoke in the cockpit of late the curve in hydraulics has less effect with heat.As far as designers how about a/c units mounted near fuel cells?was it flifgt 300 that went down near New york?

[CodeToad]

” It’s like NASCAR drivers establishing their pit road speed by the rpms...”

Sure, but the road isn’t moving as is in the air.

[em2vn]

I never had a car with an engine that could those jack rabbit starts

[calex59]

Pitot tubes are supposed to prevent such crap from happening. The thing is Air France knows, and knew about before hand, that the pitot tubes on A330s were defective and was in the process of replacing them. Why they are still flying A330s with the bad ones I don’t know, at least I am assuming this particular Airbus had the defective tubes.

[gusopol3]

The clutch helped a lot; fortunately, it was only about 20 miles. The repair was almost free ; although he never found it, the mechanic surmised some inconsequential piece of plastic from the air filter(? can’t remember) had broken loose and jammed it .

[RightOnTheLeftCoast]

"Upon closer inspection I realized that not only were the rear spars composite but so were the hinges."


AA587's vertical stabilizer left forward attachment point, from the official NTSB post-mortem photos. All composite. The composite failed due to lateral stresses. In an epic snowjob, the pilot got blamed for this.

[RightOnTheLeftCoast]

"This stuff reminds me of the Luddites."

You have a point. But the issue isn't the use but the abuse of composites. Airbus unaccountably insists on making large composite panels without incorporating metallic spars to distribute shear forces.

[cpdiii]

Dont’ know about the big airliners, but when I was an undergrad pilot training instructor pilot, I’d have my students memorize power settings for a given airspeed, both in level flight, and during landing maneuvers. That way, a failure of the pitot/static system would not prove disastrous. Sounds like that pilot had the same training.

As for the Airbus - if it ain’t Boeing, I ain’t going. Do any heavy metal drivers out there know if the aircraft had mechanical backup insturmentation for an artificial horizon? Or is the whole damn thing computer generated?

[Erik Latranyi]

Air France knows, and knew about before hand, that the pitot tubes on A330s were defective and was in the process of replacing them. Why they are still flying A330s with the bad ones I don’t know, at least I am assuming this particular Airbus had the defective tubes.

First, AF has little to do with this.....Airbus directed that all A330-200 have their pitot tubes upgraded to newer ones.

It does not seem like a critical problem or they would have grounded the planes until the tubes were replaced as it appears the directive only calls for replacement during the next maintenance cycle.

This Northwest A330 in this story may have had the new tubes.....it is not known.

Loss of airspeed is not a design flaw, it is something that happens to most aircraft on a very irregular basis....like a full tire blowout at highway speed.

Surviving is based on crew response to the event.

[calex59]

I think this is why I was never much good at flying a kite; my only solution ever to be was “run faster.”

My solution was "always fly kites on windy days!". Was never much good at getting them into the air by running.:)

[jwparkerjr]

In the report from the crew member it was reported that they had encountered rain pelting the airframe windshield and running up the windshield, and that it suddenly got very hot and humid in the cockpit. All this was way above the altitude at which you would expect to see liquid percip. My son who is a helicopter pilot had gotten a copy of the original report and forwarded it to me. I thought I still had it but couldn't find it to attach here. I'll keep looking.

[CodeToad]

“Which begs the question why every aircraft designed after 1994 (military and civilian) is FBW? Those stupid aircraft designers, don’t they know that HYDRAULICS and PIANO WIRE ACTUATION is much more reliable!”

Are you sure that decision is based on reliability and not cost?

[TXnMA]

"GPS on Tomtom etc tells you how fast you’re going. 3d vs. 2d makes this impossible in the air?"

On the GPS units I've owned, the "third D" (elevation) seems to be nowhere as high resolution as the other "two Ds"...

[GovernmentShrinker]

The Northwest Airlines scare also highlights a broader aviation hazard: Pilots depend on computer systems to navigate and control today's advanced jetliners. When these systems break down, most pilots have little hands-on experience relying on rudimentary back-up instruments.

The miracle of the Gimli Glider was an example of how valuable fundamental knowledge of low-tech/no-tech flying can be. The 69 souls who were on board definitely owe their lives to the fact the the captain just happened to pursue a glider-flying hobby in his spare time, and thus had the skills and knowledge to successfully fly and land a Boeing 767 which had abruptly and irreversibly turned into a "glider" at 41,000 feet. http://en.wikipedia.org/wiki/Gimli_Glider

[El Gato]

Part of the reason is because airlines want to reduce training costs by limiting the amount of time pilots practice in simulators.

Jeez, a major point of using simulators is that they are way, way, cheaper, on a per hour basis, than flying the actual aircraft. Plus of course the trainees can experience conditions that would be risky or impractical to "Set up" in a real aircraft.

But sims are individually pretty expensive. Full motion sims that is. A lot can be done with something not much more sophisticate than microsoft flight sim. (My company used that to build a C-130 procedures trainer. It was pretty cool, they used seat intended for small boats, and other than the controls everything else was pretty much "off the shelf stuff that you could buy at any computer store, or even at WalMart)

[El Gato]

the A330 was still working properly.

I wouldn't say that. But it was not broken either.

[Erik Latranyi]

The miracle of the Gimli Glider was an example of how valuable fundamental knowledge of low-tech/no-tech flying can be.

You forgot the more recent example of US Airways 1549, also commanded by a pilot familiar with glider control.

[GovernmentShrinker]

Yes, I was just now looking at the Wikipedia page on 1549 and saw that Sullenberger was also a glider pilot. I think I’d pay extra to be on flights with a captain or first officer that was an expereienced glider pilot. Though to be honest, I don’t think Sullenberger had much opportunity to use his glider pilot skills for the Hudson ditch. The bird strike was at 3:27:01, at 3:29:03 Sullenberger responded “Yes” to TRACON asking if he wanted to land at Teterboro, and the plane hit the water at 3:30:30. Turned out there were very few choices to be made, not to mention almost no time to make them in. Gravity ruled. He sure did get the landing angle perfect though, and that certainly didn’t happen by itself.