0
$\begingroup$

Are they deployed when the levers are pulled back to 'IDLE' or only when pulled back to 'Reverse'?

I still can't figure out, 12 years after, why flight TAM JJ3054 crashed into a gas station and a building, in São Paulo, Brazil. The investigation concluded that the captain pulled the left engine lever to reverse, but "by mistake", left the right one on 'CL'.

For those who don't remember the tragedy: 1- right reverse was pinned due to a malfunction; 2 - It was raining at the Congonhas Intl. Airport at the moment of the crash; 3 - the a320 landed on the touchdown mark on 35L runway ( about 1290 meters long); 4- Left reverse deployed but no spoilers nor hydraulic breaks engaged; 4 - Death toll: 199 souls. To this day, they can't fully determine whether the captain left the right lever on 'CL' or the FDR displayed, erroneously, 80% of thrust on right engine, when it was supposedly on 'Reverse' position. The pedestal was found among the wreckage, twisted and melted beyond recognition.

Improve this question
$\endgroup$
4
  • $\begingroup$ Your question seems perfectly legitimate in the title, but you included speculation about other things that could have caused the accident. Thus it was put on hold as opinion-based. I removed the speculative items so that the technical portion of the question can be answered. $\endgroup$
    – TomMcW
    Commented Jan 1, 2019 at 22:14
  • $\begingroup$ @TomMcW Thanks anyway. The speculations included , in my opinion, are necessary for a good brainstorm of the subject matter, since the authorities and the press in general rather conside the pilots as the responsables for the tragedy, wich is not correct. Proofs should have been presented in order to blame the pilots. But the main proof no longer exist. But we have a software controlling an aircraft wich is 100% percent reliable, right? Pilot's families still suffer under the suspicious of a possible human failure wich has never proven to be true. But thanks for the tip I understand the rules. $\endgroup$
    – user10847903
    Commented Jan 1, 2019 at 22:48
  • $\begingroup$ Problem is, brainstorming is not what the site is about. But you did ask a question than can be specifically answered, as per site rules. The specific conditions that trigger ground spoiler extension are easy to document and they are relevant to explaining the reasoning behind the conclusions made by the investigators. $\endgroup$
    – TomMcW
    Commented Jan 1, 2019 at 22:57
  • $\begingroup$ @TomMcW I understand. And I agree the question he's been properly answered. Best regards $\endgroup$
    – user10847903
    Commented Jan 2, 2019 at 0:33

2 Answers 2

Reset to default
2
$\begingroup$

PL at idle is one of several conditions (weight on wheels, N1, wheel speed etc) that have to be satisfied to get ground lift dumpers to come out on airliners. Reverse isn't required. Once on the ground, just moving the PL levers back toward TO thrust makes them come back down.

Improve this answer
$\endgroup$
1
$\begingroup$

According to the A320 FCOM the ground spoilers are extended full at landing when

both main landing gears have touched down, when:

  • Ground spoilers are armed and all thrust levers are at idle, or
  • Reverse is selected (on at least one engine, other thrust lever at idle), if ground spoilers were not armed

The ground spoilers also partially extend (10%) when reverse is selected (on at least one engine, the other thrust lever at or near idle) and one landing gear is compressed. This is to help the other landing gear to touch down, thus triggering full extension.

Here is the flowchart from the FCOM:

enter image description here source: A320 FCOM

In the case of the TAM accident, this is pertinent to the investigators’ conclusion because the pilots indicated on the CVR that the spoilers did not extend. This gives a clue as to the position of the thrust levers. The spoilers should have extended at touchdown if both levers were at idle or when reverse thrust was selected if the other lever was at or near idle. The fact that they did not extend reveals that one of the levers was not at or near idle.

This might have resulted from the captain using the old procedure for landing with a reverser disabled and he would have had a good reason to do that. The updated procedure, which was to move the levers as if both reversers were working resulted in a slightly longer landing distance than the old one (approx. 55 meters). Knowing he was landing in wet conditions it would be reasonable for him to want all the distance he could get.

It’s also reasonable to conclude he could have left a lever in climb position. The very reason Airbus had changed the procedure, even though it extended landing distance, was because pilots had made that mistake before. In the high-workload conditions at landing pilots were prone to a cognitive error of thinking that they only needed to move one lever because the other reverser was not working. In other words, during the several steps to moving the levers, on one step you move only one of them. When thinking quickly pilots would sometimes do that on the wrong step. On this occasion, combined with the poor runway condition, it resulted in disaster.

Improve this answer
$\endgroup$
1
  • $\begingroup$ Man... That's so surreal to think such an experienced airliner would do something like that. But yeah, I agree that the scenario could lead them to a mistake: poor runway, heavy aircraft, feeling somewhat tight on a (usually) difficult landing , which allows no margin for mistakes, such as Congonhas Intl.;technical limitations (pinned reverse). As to the F/O... In the heat of the moment, he probably wasn't able to see the actual position of the right lever. Panic at the cockpit :=/. Regards $\endgroup$
    – user10847903
    Commented Jan 6, 2019 at 12:12

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .