mon330
Posts: 80
Joined: Mon Nov 27, 2000 8:37 am

Reverse Thrust Usage

Thu Sep 05, 2002 8:40 pm

I was wondering if it is commonplace for a pilot to not use reverse thrust on landing if the runway is long enough. On a recent 737 flight I was on into MAN, there was no reverse thrust on landing, though the pilot did let the plane roll quite far down the runway.

My questions - is this quite common? If so, why?

Thanks.
Mark.
 
LBA
Posts: 496
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RE: Reverse Thrust Usage

Thu Sep 05, 2002 9:19 pm

This has happened to me on flights to Dublin and Stansted. Reverse thrust involves bringing up the engine to high thrust levels to slow down the a/c, by not using reverse thrust engine wear is reduced.
 
AAR90
Posts: 3140
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RE: Reverse Thrust Usage

Fri Sep 06, 2002 12:44 am

Common? Yes. "Normal procedure?" No. Most airlines prefer use of reverse thrust at higher speeds and then transitioning to wheel brakes at slower speeds. This is usually an economic decision leaving the crew to decide what's best for any given situation --runway available, environmental conditions, aircraft condition, etc.

My preference is to use minimum reverse thrust (idle only if I can afford to) consistant with a safe, smooth and economical operation. The trade-off is reduced passenger noise and heat stress on the engines vs. increased heat stress and wear on the wheel brakes. Rolling out as long as possible helps to reduce the strain on the brakes.
*NO CARRIER* -- A Naval Aviator's worst nightmare!
 
Guest

RE: Reverse Thrust Usage

Fri Sep 06, 2002 2:00 am

Just to add a bit to AAR90's comments. Thrust reversers are not required for dispatch and can be "MEL'd" out. I would guess that, on your particular flight, they were out of service and the flight dispatched without them - no big deal. For most, it not all transport category equipment, the effect of thrust reversers isn't included in the landing and takeoff performance calculations. Those numbers are based soley upon the use of aircraft brakes. Simply put, the effect that thrust reversers have on aircraft performance is basically a safety cushion or "gravy".
Jetguy
 
Mr AirNZ
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RE: Reverse Thrust Usage

Fri Sep 06, 2002 1:23 pm

Im sure I remember reading somewhere that charter airlines like to use reverse thrust (and more of it) to increase the life of the brakes.
 
Ejazz
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Joined: Wed May 22, 2002 10:26 am

RE: Reverse Thrust Usage

Fri Sep 06, 2002 4:13 pm

Autobrakes on Airliners provide a particular deceleration rate, dependant upon the setting used. This deceleration rate remains the same whether reversers are used or not, the brakes will activate as necessary to maintain the rate selected.

One condition where full reverse is desirable is when landing on a wet runway. The autobrakes may have problems maintaining a constant deceleration rate because the autoskid system will be releasing brakes as necessary to prevent a skid. The use of reversers will therefore aid the brakes.

On the majority of landings I'll use idle thrust as required in my Ops Manual, to reduce engine wear and noise. Obviously, the Airline I'm with considers brakes more expendable than an engine.

Etihad Girl, You're a great way to fly.
 
L-188
Posts: 29881
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RE: Reverse Thrust Usage

Fri Sep 06, 2002 4:41 pm

Actually the answer for why some landings don't use reverse thrust is pretty simple.

It is that scourge of free aviation everywhere.....NIMBY'S

Using the reverse thrust makes a great racket and that constantly tends to send them up and angrily buzzing around like a flock of hornets.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
 
Rick767
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RE: Reverse Thrust Usage

Fri Sep 06, 2002 6:06 pm

"Im sure I remember reading somewhere that charter airlines like to use reverse thrust (and more of it) to increase the life of the brakes."

Correct. Our airline promotes the use of full reverse whenever possible, to reduce brake wear. An automated cabin announcement is even made before landing warning the passengers to expect an increase in engine noise after touchdown!
I used to love the smell of Jet-A in the morning...
 
Ejazz
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RE: Reverse Thrust Usage

Fri Sep 06, 2002 6:18 pm

Iinteresting Rick, our policies differ again. Another major Airline that always uses full reverse thrust is Qantas.
Etihad Girl, You're a great way to fly.
 
Rick767
Posts: 2613
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RE: Reverse Thrust Usage

Fri Sep 06, 2002 6:40 pm

Always interesting how the world's airlines each have a slightly different way of doing things!

We are not forced to use maximum reverse, and indeed on some long runways we will simply engage reverse idle.

Manchester 06R is an example, we vacate the runway up towards the terminal complex right at the end and it is 10,000ft long, so we really don't need to use full reverse especially at night when the airport authority advise you to "avoid" it's use anyway.

But generally speaking we will use full reverse, and select the autobrake level which corresponds correctly to the runway length and surface condition.
I used to love the smell of Jet-A in the morning...
 
FDXmech
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: Reverse Thrust Usage

Fri Sep 06, 2002 11:59 pm

Ejazz: Iinteresting Rick, our policies differ again. Another major Airline that always uses full reverse thrust is Qantas.

Is that a recent revision in their operation since the Thailand overshoot?


You're only as good as your last departure.
 
Ejazz
Posts: 689
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RE: Reverse Thrust Usage

Sat Sep 07, 2002 1:32 am

FDX

I can't say for sure that the Bangkok incident is the reason behind their use of reverse thrust, it may have been procedure all along or introduced after Bangkok.

They are one of the few Airlines I see and hear using full reverse on every landing, most others select idle reverse.

Hopefully someone here is from Qantas.
Etihad Girl, You're a great way to fly.
 
JA54123
Posts: 128
Joined: Thu Aug 16, 2001 11:55 pm

RE: Reverse Thrust Usage

Sat Sep 07, 2002 2:56 am

Reverse thrust is not used when it is not needed. My home airport has a runway that doesn't require reverse thrust; it is over 13,000 feet long! Some airlines (WN for instance) likes to use reverse thrust so that they can stop about 1/2 of the way down the runway and turn directly to the terminal, thus reducing the taxiing and getting to the terminal faster.
You wouldn't understand, it's a Texas Thang!
 
Ejazz
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RE: Reverse Thrust Usage

Sat Sep 07, 2002 3:21 am

I think the point is missed regarding most modern Airliners with autobrakes fitted.

Assuming a dry runway and you have autobrakes 2 and idle reverse thrust selected your stopping distance in theory will be no different than autobrakes 2 and full reverse thrust selected. The computer will simply attempt to maintain a deceleration rate applicable to the autobrakes setting. More reverse thrust then less braking and vice versa.

In the Qantas incident I know the Captain initially attempted to go-around. If the aircraft had become airbourne the autobrakes would have disconnected from their setting to the off position. When he then decided to stop valuable time may have been lost until he became aware that the autobrakes were off and began to brake manually. If the procedure was also to apply only idle reverse thrust this would have compounded the lack of stopping ability and might just be why they use full reverse now if they hadn't been previously.

It might be worth adding that reverse thrust is most effective at high speeds.
Etihad Girl, You're a great way to fly.
 
CX Flyboy
Posts: 6028
Joined: Sun Dec 26, 1999 6:10 pm

RE: Reverse Thrust Usage

Sun Sep 08, 2002 12:23 am

We are another airline that uses idle reverse only. Carbon brakes work better at higher temperatures, so using them more is not a major problem. Also, apparently it costs much less to service or replace the brakes rather than the reverse thrust compoments for the actual usefullness of the thing. Remember that reverse thrust on it's own is not that useful and only equal to something like Autobrake 1, when used on it's own.

Rick767, Interesting that our policies differ. Seems SQ and CX have very similar policies though.
 
ammunition
Posts: 875
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RE: Reverse Thrust Usage

Sun Sep 08, 2002 1:10 am

I landed at BHX a month or so ago on a 767-300ER and no reverse thrust was used. I was quite surprised- but it made for a quiet and smooth run down the runway.
Saint Augustine- 'The world is a book and those who do not travel, read only 1 page'
 
Rick767
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RE: Reverse Thrust Usage

Sun Sep 08, 2002 1:19 am

Cx_flyboy,

Our SOPs are "loosely" based on those of British Airways, but use of reverse thrust is one area we also differ to them. Their policy is reverse idle, full reverse at Captain's discretion and only really encouraged in wet conditions.

Ammunition,

Out of interest, was that with Air 2000, MyTravel or Britannia?

Rick.
I used to love the smell of Jet-A in the morning...
 
ammunition
Posts: 875
Joined: Sat Feb 16, 2002 6:25 am

Rick767

Sun Sep 08, 2002 1:01 pm

It was Uzbekistan Airways, fab airline!!!
Saint Augustine- 'The world is a book and those who do not travel, read only 1 page'
 
9V-SVA
Posts: 1747
Joined: Wed Aug 29, 2001 3:54 pm

RE: Reverse Thrust Usage

Sun Sep 08, 2002 2:09 pm

SIA uses idle reverse thrust. While spotting along Changi Village Road, the only airlines that used full reverse thrust was QF and BA. Nothing could be heard from the SIA 777s and 747s landing.

9V-SVA
9V-SVA | B772ER
 
XXXX10
Posts: 702
Joined: Mon Jan 03, 2000 7:10 am

RE: Reverse Thrust Usage

Sun Sep 08, 2002 10:29 pm

Is reverse thrust (above idle) banned at certain times at certain airports?

Also for a/c having a short turnaround could their brakes be too hot for departure if they don't use full reverse?
 
Rick767
Posts: 2613
Joined: Sun Jan 30, 2000 8:11 pm

RE: Reverse Thrust Usage

Sun Sep 08, 2002 10:51 pm

XXXX10,

"Is reverse thrust (above idle) banned at certain times at certain airports?"

No, that would never be allowed. It's use is discouraged at night at several airports in the UK, but not prohibited. The official line is that reverse thrust should not be used at night "commensurate with safety and standard operating procedures". In our airline, that means we still use it.

"Also for a/c having a short turnaround could their brakes be too hot for departure if they don't use full reverse?"

Yes, the A321 springs to mind as an aircraft which sometimes has a problem with this. Airtours pulled their A321 out of Leeds Bradford (short runway) for this reason, the requirement to have the brakes at 200 degrees C or less for takeoff meant that one hour turnarounds could often not be achieved.

In case you were unaware, the A321 lands at higher speeds than the A320 since it has a greater weight but the same wing. The problem with the A321 at Leeds was that even with full reverse, the brakes did not cool down in time.
I used to love the smell of Jet-A in the morning...
 
Mr.BA
Posts: 3310
Joined: Sun Sep 24, 2000 12:26 pm

RE: Reverse Thrust Usage

Sun Sep 08, 2002 11:03 pm

I just flew twice on Qantas earlier this year on VH-OJG. We were landing at Melbourne in wet and windy conditions. It wasn't raining but the runway was pretty wet and the winds were strong so I guessed a storm just swept across Malbourne. We landed and used autobrake 4 (could any B744 pilots confirm that setting 4 is best for wet conditions?) and idle reverse. The wind was a strong cross of 21 knot when we touched down crabbed. V land was 144.

May I raise some questions? Does the system on the B744/B767 prevent skids? I have read somewhere before that the B744/B767 brake system will release brake like Ejazz has stated to prevent skidding but the Qantas incident in BKK proved that the plane could aquaplane? Is reverse thrust usage limited in crosswind conditions due to the fact that the plane would start to weathervane into the wind and reverse side force component adds to the crosswind component and drifts the airplane to the downwind side of the runway? Is there a very noticable directional control if one of the reverse fails to work espcially on twins?

Are there any charts giving figures of the deceleration rate when using full reverse thrust alone in standard day, sea level conditions?

Thanks for any imputs!

alvin
Boeing747 万岁!
 
XXXX10
Posts: 702
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Rick 767

Sun Sep 08, 2002 11:11 pm

I thought I had read that somewhere about LBA

With the night ban I thought SYD only allowed reverse idle at certain times, but as you say not if it compromises safety
 
AAR90
Posts: 3140
Joined: Fri Jan 21, 2000 11:51 am

RE: Reverse Thrust Usage

Mon Sep 09, 2002 12:02 am

>Does the system on the B744/B767 prevent skids?

No system "prevents" skids. Virtually all airliners have an anti-skid system which _attempts_ to prevent skids. Usually works quite well.  Wink/being sarcastic

>...but the Qantas incident in BKK proved that the plane could aquaplane?

See comment above.

>Is reverse thrust usage limited in crosswind conditions due to the fact that
>the plane would start to weathervane into the wind and reverse side force
>component adds to the crosswind component and drifts the airplane to the
>downwind side of the runway?

Some aircraft have limitations on the use of reverse thrust. Usually found on tail-mounted engine models. AA limits MD80 reverse thrust to (I think) 1.3 EPR, but F100 had no limit (reverser doors are blocked to provide limited amount of forward thrust at all times). B737/757/767 all are permitted unlimited reverse thrust use.

>Is there a very noticable directional control if one of the reverse fails to work espcially on twins?

Yes! Especially if failure occurs after deployment at high reverse thrust setting. Gets a bit exciting for a couple of seconds.  Sad
*NO CARRIER* -- A Naval Aviator's worst nightmare!
 
L-188
Posts: 29881
Joined: Wed Jul 07, 1999 11:27 am

RE: Reverse Thrust Usage

Mon Sep 09, 2002 12:35 am

It's use is discouraged at night at several airports in the UK, but not prohibited. The official line is that reverse thrust should not be used at night "commensurate with safety and standard operating procedures"

In real talk what it means is that unless you are about ready to go barrelling off the end of the runway, you or your chief pilot are going to get a visit from the Airport Noise Authorities and probably a pretty terse letter too.


But we won't tell you not to use it because if we did and you did overrun and not use reverse thrust, well, we just couldn't handle all of those passengers lawyers.
OBAMA-WORST PRESIDENT EVER....Even SKOORB would be better.
 
Rick767
Posts: 2613
Joined: Sun Jan 30, 2000 8:11 pm

RE: Reverse Thrust Usage

Mon Sep 09, 2002 2:13 am

L-188,

Landing on 26L @ Gatwick at night we always use full reverse (with the exception of a few Captains who go reverse idle). Landing on 08R is a different story, we can roll pretty much to the end so not much need for it.

We have never been approached by the Chief Pilot or the Airport Authorities about this, it is our SOP and the instruction clearly states that in that case it is allowed. In fact, I have flown with our Chief pilot a few times and as I recall, he does not deviate from the SOPs in view of this "rule" either.

It is our own ecomomics which dicate the procedures though, less brake wear = less cost as far as our company is concerned, however much you argue it that is there stance. I neither strongly agree or disagree with the procedure. Not senior enough for that sort of talk just yet Big grin
I used to love the smell of Jet-A in the morning...
 
FDXmech
Posts: 3219
Joined: Sun Mar 19, 2000 9:48 pm

RE: Reverse Thrust Usage

Mon Sep 09, 2002 4:07 am

Cx flyboy: Carbon brakes work better at higher temperatures, so using them more is not a major problem. Also, apparently it costs much less to service or replace the brakes rather than the reverse thrust compoments for the actual usefullness of the thing.

It would almost seem a no brainer that brake wear cost vs T/R cost would weigh heavily in favor of brakes, especially carbon brakes.

But here is something to consider. During brake overhaul, a new carbon brake heat stack costs approx. $40,000 per brake, yes 40k (MD11 or A300).

This about $14.50 per .001" of wear X brakes installed.

Each brake wears approx .0015" per landing (MD11) or .0030" for the A300-600.

Approx. 2000 landings per stack (MD11), 1000 landings for A300.

Something to consider.



You're only as good as your last departure.

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