is it safe to fly a plane with a broken thrust reverser?

Question

that airbus that crashed in sao paulo apparently had an inoperable right thrust reverser, according to the airline it was ok to fly it like this. Can a jet stop on a (wet runway) without thrust reversers?

Answer 1

Yes, operating with inoperative thrust reversers/"TRs" is OK.
Yes, it is also safe.
Yes, they can stop on brakes alone using NO thrust reverse. (Demonstrating that is part of the aircrafts certification.)

Airlines have what is called a "Minimum Equipment List" or "MEL". This is a guidebook that must be approved by the governing aviation authority (the FAA in the USA) for what can be inoperative on the aircraft and still allow it to be dispatched for flight. I can tell you that many, many things can be inoperative or broken on an airliner and it is still safe and legal to dispatch! (From the autopilot to cockpit instruments, even pressurization on some aircraft.)

Under their MEL, the airline (TAM) was permitted to operate with inoperative thrust reversers. Airlines all over the world also have this same MEL.Whether or not their aircraft performance manuals took that factor into consideration for operating on a wet ("contaminated") runway is another matter. Touching down with too much runway behind and at a faster speed than necessary may also have been factors in this accident.

Answer 2

Yes it is safe to fly a plane with a broken thrust reverser.
It is unsafe to try and land one on a known to be of marginal length, waterlogged runway in marginal weather.
In this situation, the captain, knowing he had a thrust reverser u/s could have made a decision to divert to a more suitable airport.
However this would have cost his company a fortune in transportation / hotel rooms.

These are the decisions a captain has to make on a daily basis. The give it a go mentally is covertly approved by most airlines, until something goes wrong, then it's the pilot's fault.

As to some of the other answers. At high speeds, the brakes on any aircraft are of little use on a watelogged runway, due to a phenomenon called aquaplaning, where the tyre is riding on a "wedge" of water and not actually touching the runway surface. Same effect as skidding on ice.
Add a U/S thrust reverser and you get what is known non assymetrical thrust, with a large thrust / centreline coupling moment. (distance from engine to aircraft centreline as a long lever).
This would cause the A/C to swing off the runway at speed, so the pilot would or should not have selected the thrust reversers.
So you have an aircraft, in marginal weather, poor visibilty, malfunction of a major flight system; landing on a waterlogged runway, which is known to be effectively too short in ideal cicumstances, with severely degraded braking performance.

The aircraft was safe to fly, it was as always,a chain of other linked circumstances which led to the incident.

What caused the incident? Don't know, leave it to the people paid to find out, to answer that question.

Answer 3

Yes, though it reduces the margin slightly. Reverse thrust on commercial jets produces nothing like as much as forward thrust. It may only be 10% of total available braking, but then the wheel brakes are not normally used at full force either. Some airlines only allow reverse thrust a flight idle power settings because it adds to engine wear.

Now, just to comment on some of the stupid answers.

It is way too early for all the armchair pilots to determine the final cause of the A320 overshot at Congonhas. The video of the incident appears to show the aircraft at way beyond normal speed, like 150 instead of 30, as it neared the end of the runway. Some reports have also said that he was attempting to abort the landing. So it's just as likely that this was caused by a procedural failure. Maybe the pilot found he had negligible braking and decided to go around but forgot to cancel the spoilers? Lots of maybes. Hopefully they recovered the CVR and FDR and will determine cause.

As to the "A320 engines are slow to power up"... ALL big turbofans are slow to power up. You get the majority of the thrust range in the last 15-20% of the rev range and it takes a while to accelerate the turbines to that speed before they start to accelerate the fan on the front stage of the engine that produces most of the thrust.

Without the details from the flight data and voice recorders there's little point speculating.

Answer 4

Yes, it is safe to fly without operational thrust reversers. They do assist with stopping the aircraft on the ground, but do not effect any flight a civilian aircraft would be doing.

The runway that jet crashed on was notorious for its short runway, and not having all of its thrust reversers may have contributed to the pilots decision to attempt to abort the landing.

Answer 5

It could, but there would be a lot of heat created when the brakes are applied, and as with a car, your stopping distance is multiplied about 6 fold. The mathematics would pre-suppose a full compliment of passengers, a partial fuel load if they have flown a reasonable distance etc. all these factors and more would need to be taken into account, but yes it could provided that the runway is long enough and there's no traffic around.

Answer 6

During certification test flights, all airplane landing performance is based on NO REVERSE THRUST. They cannot be guaranteed to work and there is no way to test them in the air. So when the landing data calls for a certain minimum runway length at an airport, the assumtion is made that the reversers will not be used. If they work, great. You stop shorter than you'd planned. If they don't deploy, no worries because you planned for that.

Answer 7

Av8trxx is 100% correct.

I have to correct a few comments by others, though. If you don't know, you just shouldn't answer a question. A check airman or FAA DPE would have a field day with people that answer questions that were not asked and incorrectly at that.

Curious Person: Tire chines do serve a purpose, but braking is not it. Chines are used to deflect water & slush out and away from jet engines. They are only used on aft fuselage engine mounted jets like MD80, CRJ and ERJ. I really hope you don't fly jets!

Heinz M/Mr. Top Contributor: Landing an aircraft without brakes is like driving a car without brakes. Although they sound very cool, thrust reversers are fairly useless and really don't offer more than 10% of an aircraft's total braking ability.

Answer 8

YES!!!

A320 aircraft get approximately 10% total braking from two thrust reversers. One T/R inop and deactivated (MEL'd) would only hamper braking by 5%.

Airbus engine control system (FADEC) has a very long lag time from the time the throttles move to the response of the engines (5 - 7 seconds to respond). The ECAM screen has throttle balls that tell the pilot where the engines will wind up after the throttle lag time is over.

The pilot was on a very short runway and was given no room for error. I hate to speculate on what really happened but from the information given a logical person can deduce what probably happened.

Answer 9

probably not giving an answer to the question but, if the pilot was aware of a defective thrust reverser; i am sure he would not have used it. also, why a pilot would land a defective aircraft on a specificaly difficult (short) landing strip. was the aircraft configured correctly for approach and landing? (correct flaps, speed and brakes settings?). a Quantas flight from Australia to Bangkok suffered similar problems in 99. the reason: over experienced captain (manager position at quantas) and rookie first officer who had not the balls to tell the captain that he was making a mistake. did the same story happened in Sao paulo?
the thrust reverser should have nothing to do with the unfortunate crash of this aircraft.

Answer 10

II would have thought so but I've been reading about that crash. It sounds to me that landing with a broken thrust reverser, or flying at all, especially at that airport was suicidal at best. I've read that on the average of twice a day even in daylight and in good weather, planes have to abort landing and go around if they don't touch down within the first 1000 ft. of the runway. Trying to land one that was not mechanically sound would seem to me to be a very bad idea.