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Brazil Airliner crash - Thrust reverses switched OFF

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posted on Jul, 20 2007 @ 06:54 AM
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Brazil Airliner crash - Thrust reverses switched OFF


news.bbc.co.uk

A reverse thruster on the plane which crashed in Brazil, killing some 200 people, had been deactivated during maintenance checks, the airline says.

The reversers help jets slow down on landing but Tam Airlines insisted the deactivation was in accordance with proper procedures.

The Tam Airlines' Airbus 320 overshot the runway at Sao Paulo's Congonhas airport, hit buildings and exploded.
(visit the link for the full news article)




posted on Jul, 20 2007 @ 06:54 AM
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Erm , you don`t turn off the main device for slowing an aircraft on landing - the reverses slow the aircraft to the point that the brakes can be used effectively and are an intricle part of the system; i honestly cannot see them being `deactivated` and teh aircraft allowed to fly as part of any procedure.

news.bbc.co.uk
(visit the link for the full news article)



posted on Jul, 20 2007 @ 07:33 AM
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This happens more than you think. Thrust reversers are not necessary if the runway is long enough. These days with the price of fuel being what it is most airlines have asked their pilots to stop using them when they are unnecessary. I have heard the reports that the runway at San Palo was considered too short and have to wonder if there was a mistake in assigning this particular aircraft to that flight with the reversers inoperative.



posted on Jul, 20 2007 @ 07:46 AM
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Yeah, it looks like this crash was totally avoidable.

Only the right thrust reverser was shut off, so it looks like the left one deployed as it should have.
Wouldn't that pull the plane to one side, especially on a slippery runway ???

Another fault lies in the size of the plane. Although this model was not banned from this airport, jets of similar size have been banned for some time.

It's sad that 200 people needed to die before they got the point.


EDIT:
Another snippet from the link posted above:


Globo TV also reported that the same plane had problems landing at Congonhas the day before the crash.

The channel said the plane only managed to stop at the limit of the runway. The pilot told air traffic controllers it was very slippery but did not mention any other problems



Another contributing factor that's totally human failure.


According to the Brazilian press the runway was recently reopened after repairs but had not yet been "grooved", a measure that helps pilots reduce a plane's speed.

In an interview with radio station CBN one unidentified TAM pilot said he believed the unfinished repairs had contributed to the accident. "During landings in heavy rain it is just like driving a car and feeling it skidding on the road. Grooving is not a prerequisite but it is an item of security."
www.guardian.co.uk...







[edit on 20/7/2007 by anxietydisorder]



posted on Jul, 20 2007 @ 11:45 AM
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look they are saying that to try to absolve the airport and goverment of responsibility the fact is that run way was just resurfaced and the day before the accident 2 or 3 other planes slid off that same runway.



posted on Jul, 20 2007 @ 12:17 PM
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I'm curious about the material used to resurface the runway.


New black top will leach oils to the surface on a hot day and combined with rain will make the runway that much more slippery.

Anyone know if this new surface was black top or a safer surface like concrete ?

[edit on 20/7/2007 by anxietydisorder]



posted on Jul, 20 2007 @ 12:35 PM
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How is it possible that you can disable the engines ability to reverse thrust, WITHOUT disabling the rest of the engines controls?

[edit on 20-7-2007 by johnsky]



posted on Jul, 20 2007 @ 12:39 PM
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erm sorry but your wrong

a thrust reverser is a clam shell device which moves and covers the engine jet pipe to deflect the jet thrust forward thus slowing teh aircraft.


mobarrett.net...

is a picture of a thrust reverser.



posted on Jul, 20 2007 @ 12:48 PM
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The point I was trying to get at was that it's an integral part of the engine.

The original author makes it sound like it's something separate of the engine... like a thruster on a shuttle.



posted on Jul, 20 2007 @ 01:08 PM
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well yes and no - you can disable it without effecting other engine controls.



posted on Jul, 20 2007 @ 01:23 PM
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The thrust reverser has no effect on normal operation of the engine. It is either an external section of the engine that opens and blocks the exhaust and forces it to blow forward, or it's built into the internal structure of the engine, and does the same thing. The picture that Harlequin posted is an example of the reverser used on the 737-1/200 and DC-9/MD-80 families of aircraft.

Here's a better picture of the same thing:



This is the reverse used by the plane in question, and larger aircraft:



When the engine cowling slides back it closes a clamshell around the back of the engine, closing off the exhaust. It also opens vent ports that allow the air to escape forward, slowing the aircraft.

The reversers have a circuit breaker in the cockpit that you can pull that disables them. They're activated by pulling up on the throttles, then pushing forward to increase power to help slow the plane.

[edit on 7/20/2007 by Zaphod58]



posted on Jul, 20 2007 @ 01:43 PM
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Congonhas is about 5,800 feet long. Not all that long even if you are on speed and touch down within 1000 feet of the approach end and the runway is dry and you have both reversers fuctioning.

If the runway is wet and you still have all of the above you are still ok but you better be on speed and touchdown within 1000 feet of the approach end.

If you have one reverser DMI'd that means one reverser is on 'deferred maintanance' and not operable, now you have a probelm. Although certificated runway lengths are not determined using reversers (reversers are just added safety) without them you are going to be hurting.

After looking at the video the pilot certainly was not on speed and on speed means Vref (landing speed) plus one half the wind and all of the gust. I don't know what the wind was but lets say it was 15 knots gusting to twenty we add on half the steady state which is 7.5 plus all of the gust, which is 5 kts. and add the total, 12.5 knots to the approach speed. I don't know what the gross landing weight was or Vref but lets assume Vref was 136 kts and our wind additive is 12.5 that means our approach speed is going to be 148.5 kts. Most pilots aren't going to fly that, they are going to add 10 knots for Mom and Pop. So that means he'd be coming in at almost 160 knots.

Now the video shows an airplane traveling at a high rate of speed. That airplane is smoking right along and we are looking at the last half of the runway. Just before the airplane disappears out of the frame you see a bright flash. That is the one remaining reverser being used at max reverse thrust and is stalling out the compresser causing an explosion.

It is very difficult using a single reverser because it tends to yaw the airplane and can be done but it isn't going to help that much.

What may have happened is that the pilot was way over his computed approach speed, touches down late, jams on the brakes full but they are anti-skid and will release and cycle until any kind of traction is sensed by the computer. But since the runway hasn't completing grooving there will be no traction until the airplane slows down considerably which it does not. His last option was to use full reverse on the one remaining reverser which does little or nothing at that speed.

The bottom line is that the approach to a wet, 5,800 runway with one reverser inoperative should not have been made. It was clearly pilot error as he had the final decision to land or not. The fact that he may have been under orders and intense pressure from management to complete the flight but bottom line is the pilot had the final decision.

Been there done that, got the coffee cup, got the t-shirt, got the decal but I was lucky. He wasn't.



posted on Jul, 20 2007 @ 03:00 PM
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as an idea - bournemouth international is 7451 feet

www.youtube.com...

that`s a 747 taking off - but it gives an idea of the sort of distances larger aircraft need to speed up and slow down.



posted on Aug, 10 2007 @ 09:24 PM
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The preliminary report is out. Only one reverser was disconnected. However, the pilots violated procedure, and only moved one throttle to the reverse position. Even with one reverser disconnected they should have put both throttles into reverse, which would have allowed the spoilers and autobraking systems to activate. By only moving one engine into reverse the auto systems failed to activate, and the pilots had to activate the spoilers and brakes manually, which they only tried braking with the wheel brakes and one reverser.



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