Part of doomed jet's braking system disabled, airline

[RamboLiberal]

Source: CNN/AP

SAO PAULO, Brazil (AP) -- One of the two thrust reversers on an airliner that crashed in a fireball was turned off when the plane landed, the jet's owner said Thursday.

Officials were trying to determine why the plane with 186 aboard raced down a runway instead of slowing down. The airline insisted late Thursday that the thrust reverser, used by jets to slow down just after touching down, had been deactivated earlier in accordance with proper maintenance procedures.

Meanwhile, federal prosecutors asked a federal judge to "temporarily paralyze" Congonhas airport -- a move that could disrupt air travel in Latin America's largest nation. The judge could issue a decision as early as Monday on the airport's fate.

Responding to warnings that such a move could create havoc in travel and cause severe financial repercussions for airlines, prosecutor Marcio Schusterschitz said it was better "to choose life over money." Watch debate over Sao Paulo's troubled airport »

"We think this situation has reached its limit," Schusterschitz said. "We are flying blind."


Read more: http://www.cnn.com/2007/WORLD/americas/07/20/brazil.crash.ap/index.html

[hedgehog]

1. Why in the world would you disable the brakes and leave them disabled?

It sounds like something has been lost in translation.

[karlrschneider]

2. Yeah something is definitely wrong here. A known inop reverser

is absolutely a "no-go" situation. In the U.S. anyway, I can't believe it's allowed in Brazil...they build very fine
planes themselves and are not newcomers to aviation.
If this story is true, some heads should roll.

[BlueCollar]

7. Planes are legal to fly with inop reversers in the US

Happens all the time.

reversers are not a safety of flight item and there are procedures to de-activate reversers or "placard inop".

However, once a reverser is placarded or deactivated there are restrictions as to what kind of flights the plane can make, weather conditions, runway lengths etc.

[karlrschneider]

15. Sorry, I was trying for a quick reply and didn't say it very well.

I didn't mean to imply it was actually illegal (per the FARs), but that there are a couple of things that change as you pointed out. I somehow had the idea that the pilots didn't -know- about the nonfunctioning TR, hence no placard, which seems not to be the case now that I have had more time to read about it. As far as I know, the restrictions you mention apply to the operating manuals and so only indirectly to official regulations. I've never flown an Airbus but I don't think I would very interested in trying to land one at that airport at night in the rain with broken reversers...maybe
they didn't have any option, though.

[BlueCollar]

16. I 'm thinking about your last statement

and I'm guessing, and I stress guessing, that they either didn't have any other option/diversion airport or they were under a hell of a lot of pressure to land at that airport...normally an inop reverser landing can be quite routine.

[DemoTex]

18. I'm guessing (and as an ALPA-trained airline accident investigator that is a big no-no)

I'm guessing that the approach was nowhere near stabilized. High and fast, probably, with touchdown way down that short runway. Kind of like Southwest 1455 at Burbank, Ca. on March 5, 2000.


Lucky-duckies, considering other possible outcomes to this position.

[BlueCollar]

19. I would be very surprised

if your "guess" is very far off the mark.

We'll see how it plays out. Because it was an airbus and not here in the US do you think NTSB will have any opportunity to work on the investigation?

As a mechanic I'm curious as to how/why this happened...

[DemoTex]

20. The NTSB will most probably participate as an "interested" party.

In fact, the newest member of the NTSB "Big Board" is a retired Airbus A-319/320/321 captain, who was also an ALPA airline accident investigator and airline safety expert. He happens to be an old friend of mine, too.

Other parties to the investigation could include the airframe and engine manufacturers, as well as manufacturers of brakes, T/R assemblies, avionics, etc., ATC, Brazilian regulatory agency with jurisdiction, pilots' union, mechanics union, TAM management, and possibly the US FAA.

[DemoTex]

21. An ALPA Safety Committee friend (and Airbus captain): TAM was high and fast.

Not a good combo on a relatively short, wet runway. Hell, high and fast is not a good combo for any length runway.

We used to have a gallows humor bad-news/good-news joke, appropos especially to runways 07 at Burbank and 31 at DCA (not to mention Erie, Bellingham, and LGA!): The bad news is that we are high; the good news is that we are fast.


The way it should look, at Vref+10: On profile, stabilized, low energy state.

[BlueCollar]

8. the thrust reversers are not part of the brake system

They are designed to supplement the efficiency of the brakes on the landing gear by reversing the thrust of the engine. Normally jet exhaust is expelled aft of the plane. A reverser merely redirects the air in a forward direction and assists the aircraft in slowing down.

Imagine yourself driving at a high rate of speed in a straight line and suddenly hitting the brakes in your car. You'd slow down and stop.

Now imagine doing exactly the same thing, but at the time you hit your brakes, a device on your car would suddenly force huge amounts of air forward...your stopping distance would be much shorter

[Eugene]

3. Airbus says Brazil jet OK to fly without reverser

Source: Reuters

Airbus says Brazil jet OK to fly without reverser
20 Jul 2007 18:48:45 GMT
Source: Reuters

By Tim Hepher

PARIS, July 20 (Reuters) - Planemaker Airbus <EAD.PA> <EAD.DE>
said on Friday that the type of aircraft involved in Tuesday's air crash
in Sao Paulo can fly for up to 10 days with a broken thrust reverser.

Debate over the cause of Brazil's worst air crash has shifted from the
slick runway to the aircraft's braking systems after it was disclosed
one of the A320 airliner's thrust reversers was not operating at the
time of the accident.

-snip-

Aviation experts say thrust reversers complement the brakes but are
not the aircraft's primary braking system and that it is usually safe to
fly without them.

-snip-

"Thrust reversers are not on the MEL so no rules were broken, said
Learmount, who is also a former professional pilot.

But he added: "It is a different issue as to whether it was wise in
the conditions that prevailed at the time."

-snip-

Read more: http://www.alertnet.org/thenews/newsdesk/N20238299.htm

[Ghost Dog]

5. "Thrust reversers are not on the MEL so no rules were broken"

Huh. Well they damn well should be, I reckon. Is this also the case with eg. Boeing or MD aircraft?

[KDLarsen]

6. Very much so..

To my knowledge, most airlines prefer that their pilots use idle thrust reverse, since it reduces the chance of foreign debris being sucked into the engines and causing heavy damage. Not to mention that a growing number of airports have noise reduction schemes in effect in the evening & morning hours, where idle thrust reverseis mandated. Some airports, particularly in city centers (London City comes to mind) have completely banned reverse thrust, so pilots have to rely on the wheel brakes, which is their main system of slowing down anyway.

In this case it seems like it's a multitude of factors that have been the cause. Newly surfaced runway, missing grooves to lead water off the runway and help slow down aircrafts, missing reverse thrust, heavy aircraft (it had been fuelled for the onward flight) and so on.

[high density]

4. If the pilot knew he was missing a thrust reverser

Why did he attempt this landing on this short, wet runway in the first place? (I'm assuming of course that he knew the thrust reverser was inop when the flight started.)

[BlueCollar]

9. That's the question

If the reverser was placarded and the aircraft was restricted, did the restriction include the conditions under which he attempted to land?

[DemoTex]

10. I have flown Boeing 737s and MD-80s with reversers on MEL many times.

Thrust reversers (T/Rs) may not be used for any performance data calculations, therefore there is no performance penalty with inop thrust reverser(s). Braking augmentation from reversers is gravy .. a performance freebie. Actually, the T/Rs are more of an airline economic aid than an aircraft system: they save the airline buck$ on brake wear. If the performance data says you are legal to land on the short runway at Washington National (DCA), then you are legal to land without thrust reversers.

There are a lot of engineering reasons for the lack of performance restrictions with inop T/Rs, but basically it boils down to relatively unreliable deployment, lack of redundancy, and possible asymmetries if relying on a single T/R (on a 2-engine aircraft like the 737).

Most of the time the T/Rs deploy beautifully. Occasionally, one might be slow to deploy or not deploy. That should not be a problem, although it might result in that T/R ending up with a MEL placard and a disabling pin in the deployment mechanism.

What is of much more concern is that the T/R(s) NOT deploy in flight. That can be disastrous, as was the case with Lauda Air 004 in Thailand on May 26, 1991 ( http://en.wikipedia.org/wiki/Lauda_Air_Flight_004 ). All 223 aboard that Boeing 767 died as the result of an inadvertent in-flight T/R deployment. This is the reason that any malfunction of the T/R system be considered as a possible source of a pending in-flight deployment.

Still, pilot judgment is a key in accepting any clearance to land with a T/R malfunctioning or inop. I have refused short runways that I was perfectly legal for when I thought conditions (rain, snow, crosswind, or just my frame of mind) argued in favor of a longer runway. No one should ever second guess a captain for defaulting on the side of safety. No one ever questioned my decision to take a 10 minute longer vector to a longer runway in the snow at BOS when I had an inop T/R in a fully loaded B-737-400. Besides, it's always better to have to explain why you did it than why you didn't.

On edit: TAM, the airline involved in the Sao Paulo crash, lost a Fokker F-100 with 99 passengers and crew in a 1996 crash. The aircraft had just departed the airport where the recent Airbus crash took place, Congonhas Sao Paulo, when it crashed shortly after takeoff. CAUSE: IN-FLIGHT DEPLOYMENT OF A THRUST REVERSER.

http://en.wikipedia.org/wiki/TAM_Linhas_A%C3%A9reas_Flight_402

[BlueCollar]

11. Interesting

I remember when we did the AD on the 767 reversers to prevent in-flight deployment. I wasn't aware that there had been a problem with the F-100 which I'm sure has been corrected since.

I was going to bring up in-flight deployment being a bigger problem earlier.

As a mechanic, I'd much rather fly in an aircarft that has both reversers deactivated when there's a problem with one in a twin.

You're absoloutely right about the captain's role....especially if the decision involves flying into Washington National in inclement weather. That, of all airports in the world that I have flown in or out of, gives me the heebies....

Humid in the summer makes take-off dicey from my point of view, and in the winter with ice/snow any flight operation in or out of DCA makes me hold my breath.

[DemoTex]

12. One bad T/R, pin 'em both .. I agree, but the MEL doesn't (generally).

Generally speaking, the MEL wants you to have that single T/R (even on a wing-mounted twin jet like the B767). My philosophy was always treat a single T/R MEL as a double. That is, just don't use the T/Rs after touchdown, or, at most, use only idle thrust on the operating T/R. The same thing applies when landing with one engine inoperative. However, single T/R operation produces much less asymmetry in a fuselage-mount engine configuration (like the MD-80).

I should point out that there were aircraft in the past (and might still be some) on which in-flight T/R deployment was approved during aircraft certification and was a part of some airlines' normal operating procedures. The DC-8 comes to mind. One of my old Branniff buddies tells tales of the DC-8 "shakin' like an old dog crappin' peach pits" when the two inboard T/Rs were deployed in-flight as speedbrakes. I never flew the DC-8, so I don't know.

[BlueCollar]

13. fuselage-mount engines

are the reason my personal favorite is the 727.

That, and it flies like a bat out of hell...Too bad they're slowly disappearing from the domestic fleets... :-(

[DemoTex]

14. B-727

Queen of the Fleet. Period. Did you realize that some of the earlier B-727s had nose-wheel brakes also? I think Eastern had some of those.

Armand Hammer (CEO of Oxidental Petroleum) once told me that if he didn't see a shock wave on his personal B-727s wing (on long flights) he would send word to "the boys upfront" that they weren't flying fast enough. The B-727 had 35-degrees of wing-sweep (the B-707 had 37-degrees), which is conducive to some very fast flying!

[BlueCollar]

17. nose-wheel brakes on the 727

were pretty much eliminated by the time I got to the major I work for. I think a few of the shorties still had them and they used them on the Caribbean routes. Now they use the 757s

[Javaman]

22. I wonder who was on that flight that needed to be...shall we say...

dealt with?