Reverse Thrust & X/Winds
Thread Starter
Joined: May 2002
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From: Permanently lost
Reverse Thrust & X/Winds
On a number of threads I have read that on landing with a significant crosswind, some pilots use asymmetric reverse thrust (if I have understood correctly) to prevent runway excursions.
Not having flown a jet I would like to understand what how exactly this is done. I presume reverse thrust is selected on the downwind side engine to offset weathercocking but I stand to be corrected.
Not having flown a jet I would like to understand what how exactly this is done. I presume reverse thrust is selected on the downwind side engine to offset weathercocking but I stand to be corrected.
Joined: Jul 2006
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From: USA
Not really...
No, this is utter and complete XXXXXXXX. What XXXXXXX told you
this? So, as I always say....please show me in an authoritative
document where it says to do this.
As a young, inexperienced pilot, you will fly with many captains
who are so screwed up, you'd think they have mental problems.
Some of the XXXXXXXX they come up with is quite entertaining.
If the civil aviation authorities have a sense of humor, they'll
laugh like hell, just before they begin filling out the paperwork
for certificate action and issuing the fines....
this? So, as I always say....please show me in an authoritative
document where it says to do this.
As a young, inexperienced pilot, you will fly with many captains
who are so screwed up, you'd think they have mental problems.
Some of the XXXXXXXX they come up with is quite entertaining.
If the civil aviation authorities have a sense of humor, they'll
laugh like hell, just before they begin filling out the paperwork
for certificate action and issuing the fines....
Joined: Aug 1998
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From: Ex-pat Aussie in the UK
I have never heard of it being done, and it is specifically warned against in the Boeing manuals.
There IS a technique of cancelling reverse in the event of a skid, as the reverse will be "pulling you off the side of the runway" when the tail is pointing at the side of that runway, rather than in-line with the runway centre-line.
There IS a technique of cancelling reverse in the event of a skid, as the reverse will be "pulling you off the side of the runway" when the tail is pointing at the side of that runway, rather than in-line with the runway centre-line.
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From: Cambridge
Chill out Pantload, the guy was only asking a simple question. Mis-informed as he may have been, there is no need to jump on your high horse and start a rant. Perhaps you're the one who should be taking the Prozac.
Thread Starter
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From: Permanently lost
Gentlemen, I did say I might have misunderstood what had been said which is why I asked the question.
Is there a situation where reverse thrust may not be used because of a crosswind situation? That is, use of reverse thrust may cause the aircraft to become unstable during the roll-out.
Is there a situation where reverse thrust may not be used because of a crosswind situation? That is, use of reverse thrust may cause the aircraft to become unstable during the roll-out.
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From: La Belle Province
To answer the last one, yes.
On some types the reverser plume interferes with the aerodynamics, either of the wing or the tail (depending on engine location). If the aircraft has limiting or marginal xwind capability, this plume interference may adversely affect the handling, further restricting the capability.
On Challenger 604, for example, the crosswind capability without using TRs is 24 knots DEMONSTRATED and no explicit Limitation exists. With use of TRs that 24 knots becomes a LIMITATION.
On other aircraft, limits are specified on the level of reverse thrust which may be used, in part to ensure adequate controllability is maintained. Loss of directional stability in a crosswind would be unpleasant. (Note - I doubt there is no stability at 24.5 knots - but the OEM and the cert authorities doesn't want you to go trying it to find out!)
On some types the reverser plume interferes with the aerodynamics, either of the wing or the tail (depending on engine location). If the aircraft has limiting or marginal xwind capability, this plume interference may adversely affect the handling, further restricting the capability.
On Challenger 604, for example, the crosswind capability without using TRs is 24 knots DEMONSTRATED and no explicit Limitation exists. With use of TRs that 24 knots becomes a LIMITATION.
On other aircraft, limits are specified on the level of reverse thrust which may be used, in part to ensure adequate controllability is maintained. Loss of directional stability in a crosswind would be unpleasant. (Note - I doubt there is no stability at 24.5 knots - but the OEM and the cert authorities doesn't want you to go trying it to find out!)
Aviator Extraordinaire
Joined: May 2000
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From: Oklahoma City, Oklahoma USA
I hate to start a fight here, but I guess I'm going to anyway.
I have used asymmetric reverse thrust in jet aircraft in strong cross winds on contaminated runways and had zero problems.
I have used asymmetric reverse thrust in jet aircraft in strong cross winds on contaminated runways and had zero problems.
Joined: Feb 1998
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From: Formerly of Nam
I have used asymmetric reverse thrust in jet aircraft in strong
cross winds on contaminated runways and had zero problems
cross winds on contaminated runways and had zero problems
and DC9s have thrust vectors close together, so the assy
effect would be diddlys.
A slight assymetric reverse on the 737 helped a bit in the
rare contaminated landings I've done (snowy ice slop) but
I'd never try it in a Scarebus - too many things could go
wrong on the bloody thing.
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From: earth
I'd never try it in a Scarebus - too many things could go
wrong on the bloody thing.
wrong on the bloody thing.
Suppose the question is who or what the hell is flying the aircraft? Why have a pilot when automation possibilities are advanced enough to operate UAV's. LIABILITY.. This is what drives our existence.
I have an A&P, started out working with guys who had been on similar pay scales with drivers in the 70's and 80's.
Cheers to the Airman Pilots who have been successful in negotiating great wages.
What I am getting at, to the point is piloting skills are forgone, procedure is priority despite your better judgment.
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From: Australia
See "Slowing down in a crosswind" thread by username Hakeem on this current forum. Maybe the Mods could combine both threads seeing they are both on the subject of slippery runway crosswind landing technique?
Aviator Extraordinaire
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From: Oklahoma City, Oklahoma USA
Yeh but are you talking Deisel-8s or 707s Con? And 727s
and DC9s have thrust vectors close together, so the assy
effect would be diddlys.
and DC9s have thrust vectors close together, so the assy
effect would be diddlys.
And a 'Hi ho Sliver' and off into a snowbank they go. Minor aircraft damage, but severe pilot ego damage.
I have a photo of a G-IV off the side of the runway in Vail due to the same problem, I'll look for it.
And when I was with the Marshal Service our only real Deputy US Marshal pilot managed to run a Sabre 80 off the runway into the grass, collapsing the nose gear before they stopped. But in this case one of the reversers was in-op and had been pinned closed. After this accident, we changed the 'One reverser In-op' procedure to pin both reversers closed.
There was really no reason to pin both, we always had problems with the reversers on the Sabre 80s. One just had to slowly add power after the working reverser opened. But, the weakest link has to accounted for, so the procedure was changed.
Fleet Manager
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From: various places .....
For interest, on some DC9 runway testing years ago and operating in moderately strong crosswinds, the TP chose to use asymmetric reverse during accel stops and had no difficulty.
However, I think the line pilot is more at risk using asymmetric reverse than idle reverse with coarse rudder input ?
However, I think the line pilot is more at risk using asymmetric reverse than idle reverse with coarse rudder input ?
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From: UK
Crosswind Landings.
Also at http://www.skybrary.aero/bookshelf/books/871.pdf
Fig 6 and the associated text covers the principles – keep the thrust contribution symmetrical, particularly as the runway friction decreases.
Also at http://www.skybrary.aero/bookshelf/books/871.pdf
Fig 6 and the associated text covers the principles – keep the thrust contribution symmetrical, particularly as the runway friction decreases.
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From: Omicron Persei 8
Perfectly acceptable to operate the B737-800/900 with only one operating reverser, which would of course mean you have asymmetrical reverse thrust. There are no x-wind limits per se.
From my company's MEL:-
OPERATIONS (O)
NOTE: Thrust reverser deactivation can result in the illumination of the MASTER CAUTION and ENG annunciation when performing a Master Caution recall.
1. During rejected takeoff and landing rollout, use the operative thrust reverser normally and, use the rudder and brakes to maintain aircraft directional control.
2. For wet and contaminated runways, apply weight and V1 reduction by no reverse thrust option in the QRH.
3. For dry runways, no performance correction is necessary.
From my company's MEL:-
OPERATIONS (O)
NOTE: Thrust reverser deactivation can result in the illumination of the MASTER CAUTION and ENG annunciation when performing a Master Caution recall.
1. During rejected takeoff and landing rollout, use the operative thrust reverser normally and, use the rudder and brakes to maintain aircraft directional control.
2. For wet and contaminated runways, apply weight and V1 reduction by no reverse thrust option in the QRH.
3. For dry runways, no performance correction is necessary.
Aviator Extraordinaire
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From: Oklahoma City, Oklahoma USA
Just because something isn't mentioned in (M)MEL doesn't mean it doesn't matter.
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From: La Belle Province
What I meant was, if a consideration for operation with a MMEL item isnt listed, it doesn't mean it isnt important.
So for the post before mine, although it listed 3 items for operation with a TR on the MMEL, it didn't mention Xwinds, but that doesn't mean that Xwinds may not be a factor when operating with a MMEL TR.
So for the post before mine, although it listed 3 items for operation with a TR on the MMEL, it didn't mention Xwinds, but that doesn't mean that Xwinds may not be a factor when operating with a MMEL TR.