Tg 747-300
Topic Author
Posts: 1282
Joined: Fri Nov 26, 1999 6:08 am

Use Of Thrust Reversers During Descent

Sun May 05, 2002 5:29 am

I was wondring if aircrafts , mainly DC9 and MD80 , can use the thrust reversers to slow down during descent.

I'm asking since i have an idea of having experienced that on a SK MD80 back in 1999

tg 747-300
intentionally left blank
 
jcxp15
Posts: 989
Joined: Fri Jun 29, 2001 12:05 pm

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 5:48 am

As far as I know it's not possible for planes to use reversers in flight. There is a safety mechanism which prevents this. Wasn't there that theory about Swissair 111 about how the reversers went off, being the cause of the crash? This has obviously changed. From what I know, reversers in flight can be catastrophic.
 
Tg 747-300
Topic Author
Posts: 1282
Joined: Fri Nov 26, 1999 6:08 am

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 6:12 am

I think its the Lauda 767 accident near Bangkok ,Thailand that you are remembering. If I'm not wrong one of the thrust reversers deployed during climb, causing one engine to reverse and the other to push foreward. And wasn't tha crew a litle unsure about whatwas going on?

tg 747-300
intentionally left blank
 
JETPILOT
Posts: 3094
Joined: Tue May 18, 1999 6:40 am

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 6:24 am

DC8 can go into reverse thrust in flight.

Full reverse available on the inboards at all times, and idle thrust avaialable on the outboards with the gear down and locked.

Not sure about the 70 series with the CFM engines though.

JET
 
bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 6:27 am

I believe I have read on this forum previously that the DC8 has the ability to deploy the reversers during flight with some sort of override mechanism. But please confirm that; not 100% on this one.

-bio
 
bio15
Posts: 1048
Joined: Fri Mar 23, 2001 8:10 am

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 6:29 am

Yea, there you go, Jet has already resolved it.  Smile
 
Ivo21
Posts: 25
Joined: Sun Jan 13, 2002 8:52 pm

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 7:08 am

The thrust reverse system can only be used when the antiskid/autobrake system senses a ground mode. The autobrake system can use the reverse thrust if needed for the set deceleration rate. As far as I know the thrust reversers cannot be used in flight.

CU

Ivo
 
TurbineBeaver
Posts: 1511
Joined: Fri Jan 11, 2002 1:50 am

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 7:39 am

Guys, my memory is vague, BUT...

Isn't this the main plot in...Michael Crichton's(??) novel, Airframe about the Norton 11 or some sort of airplane over the pacific? It's been about 4 years since I read the book, so I can't remember completely.

TB
 
Starship
Posts: 1038
Joined: Wed Nov 24, 1999 3:26 am

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 9:23 am

The Boeing C-17 Globemaster III has four Pratt & Whitney PW2040 series turbofans equipped with directed-flow thrust reversers capable of deployment in flight.

I think I have something on video somewhere, where they state that with the use of in flight thust reversers, the C-17 can descend at the rate of 16 000 ft/min and then land in as little as 1 400 ft. Mighty impressive and worthy of its 22 world records.
Behind every "no" is a "yes"
 
Hurricane
Posts: 1357
Joined: Fri Feb 01, 2002 11:39 am

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 10:19 am

Turbine...I thought Airframe's crash was caused by an inflight involuntary slats deployment...
 
shaun3000
Posts: 439
Joined: Thu Mar 14, 2002 4:10 pm

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 12:39 pm

Yes, Hurricane, _Airframe_ revolved around an inflight slat deployment.

In regards to thrust reversers in flight, I recall reading a thread on this forum a while back where some guy was on a 737-200 that had to make an emergencey decent. He said the pilot had full spoilers and thrust reverse, among other things, to slow the plane during the very rapid decent.

So I suppose it is possible on some planes.
 
SkyGuy11
Posts: 532
Joined: Fri Oct 26, 2001 7:09 am

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 1:57 pm

There is a modified Gulfstream NASA uses to train their Space Shuttle pilots. They go up really high (I forgot the specifics of it) and deploy spoilers and full reverse thrust to simulate the glide ratio of a Space Shuttle (some glider!).
.
 
miles_mechanic
Posts: 132
Joined: Sat Sep 08, 2001 4:30 pm

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 4:11 pm

I saw the article on CNN about the shuttle training aircraft, they said that the modified Gulfstream goes up to 40,000 ft., and about 4 miles out and does there approach to the runway with the reverser thrust engaged. They showed the view from inside as they performed the manouver, what a ride that must be. They don't take the reverse thrust off until they are over the runway, but the pilot said they could land with them still deployed. The airplane has special computer controls installed to ensure that both engines are putting out the same thrust in reverse so they don't loose control of the airplane.

Miles
 
L-188
Posts: 29881
Joined: Wed Jul 07, 1999 11:27 am

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 4:26 pm

I have seen photos of IL-62s on final that have had the outboard engines reversers deployed.

Probably for the same reason that it is used on the DC-8.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
 
Guest

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 7:26 pm

Oh by the way, on the NASA Gulfstream Shuttle trainer, they also extend the main landing gear for additional drag. What a ride that must be - spoilers, main landing gear, and full reverse thrust...
Yee Haw!
 
POSITIVE RATE
Posts: 2121
Joined: Sun Sep 16, 2001 11:31 am

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 8:43 pm

Reverse- thrust is available on some a/c types in flight. DC-8/NASA Gulfstream jet and possibly the 747. However it is not possible on a twin engine jet like a 767 because the engines are too far inboard and they would get wrenched off and the plane would break apart(Lauda Air 767-300ER in 1991). There is however a recovery manouver for pilots in case the reversers do inadvertently deploy- about a 3 sec window from reverser deployment to airframe failure for the pilots to take action!
 
vc10
Posts: 1352
Joined: Thu Nov 15, 2001 4:13 am

RE: Use Of Thrust Reversers During Descent

Sun May 05, 2002 9:11 pm

In my experience most aircraft whether prop or pure jet have a built in automatic protection system which will prevent the engine going into reverse thrust in the air, or should that happen then the engine power will be reduced to idle power. Now some aircraft have a system which at the pilots command overrides that ptotection system and allows certain engines to go into reverse thrust usually at very low powers while the aircraft is airbourne.
From my own experience an engine inadvertantly going in reverse in flight is not always a disaster as is shown by my own example when flying a VC-10 at 35,000ft when the No 3 engine [and on a Vc-10 that is quite inboard ] decided to go into reverse. The auto protection system immediately reduced the power to idle thrust, and in fact it was all to much for the engine which flamed out. Yes the situation was not very pleasant and not to be repeated by choice , but the aircraft landed on time and I seem to remember it departed only slightly late [ Due reverser being locked out ]
Just for interest the Concorde once it is below Mach 1 and I believe 30,000ft can select it's two inboard engines into reverse thrust at idle power. This is usually done so as to increase the rate of descent, which with idle reverse in will be about 10,000ft per min.

Regards little vc10
 
Starship
Posts: 1038
Joined: Wed Nov 24, 1999 3:26 am

RE: Use Of Thrust Reversers During Descent

Mon May 06, 2002 3:44 am

L-188 is quite correct about the IL-62 deploying thrust reversers in the air. However after scanning through a few hundred pics in the database, I came to the conclusion that the thrust reversers are deployed only seconds before touchdown. The pic I really wanted I haven't found yet, but I'll carry on looking. In the mean time, here are two illustrating deployed TR's in flight.


View Large View Medium
Click here for bigger photo!

Photo © Malc Southern
View Large View Medium
Click here for bigger photo!

Photo © Josep Duran



Behind every "no" is a "yes"
 
JETPILOT
Posts: 3094
Joined: Tue May 18, 1999 6:40 am

RE: Use Of Thrust Reversers During Descent

Mon May 06, 2002 7:57 am

Thats crazy !!!!!

JET
 
Guest

RE: Use Of Thrust Reversers During Descent

Mon May 06, 2002 10:38 am

The DC-8 is probably the only commercial airliner that can safely deploy thrust reversers in the air but that is highly discouraged. Recently one was inadvertently deployed to no ill effect.

I know for sure that the C-17 can deploy thrust reversers for extremely steep descents but then it's a military aircraft.

Regards,
Nut
 
jhooper
Posts: 5560
Joined: Thu Dec 13, 2001 8:27 pm

RE: Use Of Thrust Reversers During Descent

Mon May 06, 2002 10:41 am

A thrust reverser came open on a C-5 back in the Gulf War, causing a crash. I wouldn't try it, because it really isn't needed. Spoilers are more than adaquate on more aircraft.
Last year 1,944 New Yorkers saw something and said something.
 
Guest

RE: Use Of Thrust Reversers During Descent

Mon May 06, 2002 11:18 am

The DC-9 can deploy the reversers inflight. There is no mechanical linkage to prevent the thrust reversers from deploying. That's not to say that it's a procedure. The same was true with the 707. Forbidden by the manual, but nothing mechanical to prevent inflight actuation.
 
exPratt
Posts: 306
Joined: Wed Mar 08, 2000 6:15 am

RE: Use Of Thrust Reversers During Descent

Mon May 06, 2002 2:03 pm

The DC-8s were originally certificated to permit inflight deployment of the T/Rs. But I thought the FOM was revised to prohibit the inflight use of the T/Rs after two crashes where crews deployed the T/Rs on final approach at low altitude. One crash was Alitalia at JFK and I believe the other was IB at BOS. I think both had similar circumstances and outcomes. The airplane broke out of the clouds and were high on the glide slope on short final. The captains did not want to go around and deployed the T/Rs that caused a very high sink rate causing the airplanes to land short and hard. Both airplanes broke up into three pieces, but did not burn. There were several injuries, but no fatalities.
 
atlamt
Posts: 244
Joined: Thu Sep 13, 2001 12:15 am

RE: Use Of Thrust Reversers During Descent

Mon May 06, 2002 6:43 pm

I saw a video from Douglas about the flight testing of the md-88. They deployed one thrust reverser inflight (the engine was at idle) and the plane continued along no problem.
Fwd to MCO and Placard
 
air2gxs
Posts: 1443
Joined: Mon Jun 18, 2001 1:29 pm

RE: Use Of Thrust Reversers During Descent

Tue May 07, 2002 11:01 am

As far as I know reverser deployment is still allowed, though discouraged on the DC8. JETPILOT, the reversers are still active in flight on the CFM equipped aircraft.
 
737doctor
Posts: 1291
Joined: Mon Mar 19, 2001 4:52 pm

RE: Use Of Thrust Reversers During Descent

Tue May 07, 2002 11:53 am

Air2gxs, you are correct.

You can deploy the inboard reversers on 70-series DC-8's in lieu of speed brakes in flight.
Patrick Bateman is my hero.
 
Bellerophon
Posts: 522
Joined: Thu May 09, 2002 10:12 am

RE: Use Of Thrust Reversers During Descent

Fri May 10, 2002 12:25 am

Concorde can use reverse thrust in the air.

Vc10 was correct, only the inboard engines are used in the air, never the outboards. Reverse idle only, when subsonic and below 30,000 ft, plus a few other limitations.

The descent profile is planned without the use of reverse thrust, but it is available, and used, if required.
 
spk
Posts: 431
Joined: Fri Jun 08, 2001 1:56 am

RE: Use Of Thrust Reversers During Descent

Fri May 10, 2002 4:17 pm

FAA does require the manufacturer to proof that the aircraft can continue flying if the reverser is deployed in flight. In many aircrafts, this certification is done in flight.

In the case of 767, the real test was not done and the design was accepted based on calculations. In real scenario, however, unknown to the designer, the exhaust from the reverser was blown over the wing, causing the wing to lose lift. That, in turn, cause an excessive roll which has recovery window of only 4 seconds.

The certification calculation did not include the effect of the jet exhaust that cause lost of lift. The effect was found only after the accident when Boeing simulated the reverser effect in wind tunnel.

That implies that in flight reverser deployment in a 767 means death if not recovered within 4 seconds (deflect full rudder and aileron in opposite direction).

The cause of the accident was pointed at the interlocking circuitry of the reverser. Under certain failure mode, the electricity can leak through a circuit and cause in flight reverser deployment. The circuit has been redesigned.
 
Guest

RE: Use Of Thrust Reversers During Descent

Fri May 10, 2002 7:42 pm

If I'm not mistaken, the 767 incident resulted in a "Thrust Reverser Armed" max speed limitation of 180 knots being placed on certain aircraft. As I remember, that was the reason that they us when it came out in the Astras.

Who is online

Users browsing this forum: bentzur, DrPaul, marrus, wilcharl and 18 guests

Popular Searches On Airliners.net

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos