EMAman
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NG4 Disaster: 25th Anniversary

Tue May 24, 2016 9:42 pm

The 25th anniversary of the Lauda Air Flight NG4 disaster is looming on 26th May.

I remember the day well, as a 10 year old I was already highly interested in aviation.

In 2009 it also became my daughters birth date, so will never forget the date.

RIP to all 223 on board, sadly lost but never forgotten. Cant believe 25 yrs could whip by so quickly.
 
EMAman
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RE: NG4 Disaster: 25th Anniversary

Tue May 24, 2016 9:47 pm

I would perhaps add that this was the only real mass fatality B767 disaster in history - that was the fault of the aircraft.
 
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777Jet
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 2:38 am

R.I.P. to the victims...

The stories about some locals taking the victim's valuables was quite disturbing.

The Thai report:

http://www.rvs.uni-bielefeld.de/publ...mAndRep/LaudaAir/LaudaRPT.html#3.2
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IndianicWorld
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 3:39 am

RIP to all the victims.

Quoting EMAman (Reply 1):
I would perhaps add that this was the only real mass fatality B767 disaster in history - that was the fault of the aircraft.

It was 1 too many but at least it has not occurred again since.
 
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TheFlyingDisk
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 5:48 am

I still am actually confused over this accident - how is it that an unlocked thrust reverse can bring down this aircraft? If I recall correctly some aircraft model actually had in flight thrust reverser deployment but didn't flip over & crashed the way NG4 did.
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bennett123
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 6:21 am

Was it an asymetric deployment.
 
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LAX772LR
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 7:21 am

Quoting IndianicWorld (Reply 3):
It was 1 too many but at least it has not occurred again since.

Define "it"-- because there have been other subsequent incidents where the thrust reverser opened and caused flight disruption and/or crash.

JJ402 comes to mind, though a big part of that was horrifically negligent (lack of) training on behalf of the airline and RR.


Quoting TheFlyingDisk (Reply 4):
how is it that an unlocked thrust reverse can bring down this aircraft?

On a wing-mounted commercial aircraft, the reversed backwash is going to seriously impede airflow over the wing, likely causing a stall in that wing while the other continues to produce lift.

It can (and in the case of NG004, did) put the plane into an irrecoverable dive, in which it quickly went supersonic and broke up middair as a result.



Quoting TheFlyingDisk (Reply 4):
I recall correctly some aircraft model actually had in flight thrust reverser deployment but didn't flip over & crashed the way NG4 did.

Some aircraft (almost all of them rear engine-mounted) are designed to intentionally have reversers open in flight, and be just fine. Concorde could do it, as could TU154, IL62, and IINM the Trident.

Soviet aircraft did it rather routinely, to slow down on approach. See for yourself:
http://www.youtube.com/watch?v=Yq5HLtdGeqE
http://www.youtube.com/watch?v=N29ZFnQfm7I

Some military aircraft can as well.

[Edited 2016-05-25 00:34:02]
I myself, suspect a more prosaic motive... ~Thranduil
 
IndianicWorld
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 8:25 am

Quoting LAX772LR (Reply 6):
Define "it"-- because there have been other subsequent incidents where the thrust reverser opened and caused flight disruption and/or crash.

My point related to the 767, which my post was referring to.
 
maxpower1954
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 2:47 pm

Quoting TheFlyingDisk (Reply 4):
Some aircraft (almost all of them rear engine-mounted) are designed to intentionally have reversers open in flight, and be just fine. Concorde could do it, as could TU154, IL62, and IINM the Trident.

The DC-8 used inflight reverse thrust on the inboard engines for speed brakes.
 
KC135Hydraulics
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 3:39 pm

Quoting maxpower1954 (Reply 8):
The DC-8 used inflight reverse thrust on the inboard engines for speed brakes.

The C-17 does as well quite routinely.
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aviatorcraig
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 3:52 pm

OK, some of these aircraft mentioned can use reverse thrust as a means of speed braking in the slower end of the flight envelope. How many can deploy reverse thrust whilst cruising at around mach 0.8 in the thin air of typical cruising FLs where your stall speed, cruise speed and never exceed speed are all uncomfortably close to each other?
I would guess the number is quite small, like around zero!
707 727 Caravelle Comet Concorde Dash-7 DC-9 DC-10 One-Eleven Trident Tristar Tu-134 VC-10 Viscount plus boring stuff!
 
Sooner787
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 4:40 pm

I remember that crash because I flew an AA 763 from DFW to SAN that same night.
I specifically remember landing at SAN without deploying the reversers and
rolling out the full length of the runway after landing. Nothing dramatic
but I was wondering whether they'd use the reversers when we landed.
 
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cougar15
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 4:43 pm

Quoting Sooner787 (Reply 11):
I remember that crash because I flew an AA 763 from DFW to SAN that same night.I specifically remember landing at SAN without deploying the reversers and rolling out the full length of the runway after landing. Nothing dramaticbut I was wondering whether they'd use the reversers when we landed.

Doubt that was related, root cause analysis took some months..........  

Sad accident indeed, there is a recent Air Crash investigate/Mayday Episode on it on youtube
some you lose, others you can´t win!
 
SpaceshipDC10
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 4:44 pm

Quoting TheFlyingDisk (Reply 4):
I still am actually confused over this accident - how is it that an unlocked thrust reverse can bring down this aircraft? If I recall correctly some aircraft model actually had in flight thrust reverser deployment but didn't flip over & crashed the way NG4 did.

The aircraft was still climbing when it happened. It was at FL247 and flying at M 0.78.

Recovery 'window':

- immediate full opposite rudder & aileron
- only 4 sec. available, 6 if number 2 is immediately idled
- recovery impossible after 6 seconds, roll through 90°+ and 25% lift loss on port wing

At 8 seconds, fuel cutoff and No1 spools down

Between 11 and 22 seconds after reverse deployment:

-empennage overloads, 15,000ft descent, fin tears out mounting to left, port stabilizer fails

23-29 sec: breakup

After just 3 seconds of reverse deployment, the CVR recorded a metallic snap, so I let you imagine the forces that were at play during those 22 seconds .

Source: Air Disaster volume 2
 
penguins
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 5:03 pm

Quoting Sooner787 (Reply 11):
I remember that crash because I flew an AA 763 from DFW to SAN that same night.
I specifically remember landing at SAN without deploying the reversers and
rolling out the full length of the runway after landing. Nothing dramatic
but I was wondering whether they'd use the reversers when we landed.

Quoting cougar15 (Reply 12):
Doubt that was related, root cause analysis took some months..........  

Agreed. There's no way the cause of the crash was known by then.
 
Sooner787
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 5:15 pm

Quoting penguins (Reply 14):
Agreed. There's no way the cause of the crash was known by then.

I remember a news report the afternoon before my flight that said FAA had ordered 767 operators
not to use their reversers until told otherwise as a result of that crash.
 
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cougar15
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 5:26 pm

Quoting Sooner787 (Reply 15):
I remember a news report the afternoon before my flight that said FAA had ordered 767 operators
not to use their reversers until told otherwise as a result of that crash.

may want to watch this.... it took quite a while to work out the cause, certainly NOT the same day! cheers

http://www.youtube.com/watch?v=GX1dXv-z5IQ
some you lose, others you can´t win!
 
klwright69
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 5:30 pm

That was quite an accident. I remember the Air Crash Investigation on this accident. It seems there are many accidents due to pilot error or terrorism. This one was purely mechanical.
 
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LAX772LR
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 5:52 pm

Quoting Sooner787 (Reply 15):
I remember a news report the afternoon before my flight that said FAA had ordered 767 operators not to use their reversers until told otherwise as a result of that crash.

Not sure how that could be, as they had no idea that the thrust reverser caused the crash, until hearing the CVR... and that didn't happen until several days later. Initial suspicion was that the aircraft had been bombed.

No way that there could've been an FAA order on the same night.
I myself, suspect a more prosaic motive... ~Thranduil
 
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LAX772LR
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 5:55 pm

Here's an interesting short VIDEO.

The DC8 is one of the few wing-mounted commercial aircraft that can handle an inflight reversal, and do so reasonably well.
The FAA used one in this testing post NG004, to study airflow effects for a reversal during flight:

http://lessonslearned.faa.gov/Lauda/LeadingEdge_pop_up.htm
I myself, suspect a more prosaic motive... ~Thranduil
 
maxpower1954
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RE: NG4 Disaster: 25th Anniversary

Wed May 25, 2016 8:00 pm

Quoting aviatorcraig (Reply 10):
OK, some of these aircraft mentioned can use reverse thrust as a means of speed braking in the slower end of the flight envelope. How many can deploy reverse thrust whilst cruising at around mach 0.8 in the thin air of typical cruising FLs where your stall speed, cruise speed and never exceed speed are all uncomfortably close to each other?
I would guess the number is quite small, like around zero!

At least one - the mighty DC-8!

From my 1978 Airlift International DC-8 emergency procedures handbook:

Emergency Descent
O2 Masks and interphone - ON, 100%
Thrust levers - IDLE
Engines 2 and 3 - MAX REVERSE UP TO MCT (max continuous thrust)
Speed - Mmo/Vmo (redline) or as limited by structural damage.
Altitude - Descend to 10,000 MSL

Only limitations to reverse inflight - flaps must be retracted and speed greater than 210 knots.
 
xdlx
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RE: NG4 Disaster: 25th Anniversary

Thu May 26, 2016 11:01 pm

Did the -73 retain this procedure/feature?
 
maxpower1954
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RE: NG4 Disaster: 25th Anniversary

Fri May 27, 2016 1:56 am

Quoting xdlx (Reply 21):
Did the -73 retain this procedure/feature?

Yes it did. The DC-8 spoiler system are ground spoilers and lateral control (assisting the ailerons at lower speeds) only. Reverse thrust is the only in flight speed brake on all DC-8s.
 
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777Jet
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RE: NG4 Disaster: 25th Anniversary

Fri May 27, 2016 3:18 am

Sad that this wasn't prevented given the number of times the left thrust reverser required attention:

http://www.rvs.uni-bielefeld.de/publ...mAndRep/LaudaAir/LaudaRPT.html#1.6

"Technical logs, component status records, and the Lauda trouble shooting file maintained by their Maintenance Control were reviewed as far back as November 30, 1989. Since August 14, 1990, there were 13 maintenance actions logged on the left engine thrust reverser system, almost always in response to recurring Propulsion Interface Monitor Unit (PIMU) messages of "EEC CH-B REVERSER RNG FAIL" and "EEC CH A/B REV CR-CHK FAIL." Ten of these actions occurred since January 28, 1991. The majority of the corrective actions involved removing and replacing valves or actuators, and adjustments to the system. Typically then the PIMU message would not reoccur for several flights. The most recent known action prior to the accident was on May 25, 1991 at Vienna. At this time, a left engine thrust reverser locking actuator was replaced. Lauda had accomplished all the troubleshooting steps from the Boeing Fault Isolation Manual (FIM) without correcting the problems of the recurring PIMU messages. The company continued to dispatch the airplane on its regular schedule, with troubleshooting accomplished after return to the home station. Lauda personnel stated, they were in the process of conducting a complete inspection of the left thrust reverser wire bundle for damage before the accident occurred. The last record of visual inspection for the wiring was entered in a trouble shooting log, kept by Lauda Maintenance Department, on March 26, 1991. Dispatch of the airplane with the particular PIMU messages was permitted under a time limited dispatch condition as outlined in the airline's maintenance planning document. The Boeing Dispatch Deviation Guide cites the Pratt and Whitney Type Certificate Data Sheet E24NE, which permits dispatch for up to 500 operating hours with a EEC maintenance message annunciated.

The right engine thrust reverser had three maintenance items logged against it since August 14, 1990, and these were all for reasons of component wear and service bulletin requirements."

[Edited 2016-05-26 20:36:04]
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