Idle Reverse while vacating

[Airmann]

Does anyone here have an opinion with regard to keeping reversers at idle while vacating the runway after landing when the aircraft is still decelerating (i.e. entering the taxiway). Any possible risks associated with doing this?

While vacating on high speed exits I usually keep reverses at idle until I'm down to a taxi speed that I'm happy with, I don't find any point in selecting forward idle while still decelerating. This means having reverse idle while on an exit.

[Check Airman]

I'm sure they're risks. There's risk associated with walking down the stairs. I do it when necessary, with your logic. Why stow them when you're still decelerating?

[lomapaseo]

Vacating the runway, while in reverse is one of the highest risk areas for blowing around debris to be ingested by engines. When I used to fly the four holers I could count on a shower of visible fan sparks in the inlet if the pilot left the outboard reversers on when turning off the runway

When I conducted airport debris investigations, I would always note the highest risk areas were at the turning points between runways and taxiways. And a few stories about high power spoolups on the chevrons where only the few dare to go

[vilas]

Forward idle adds considerable thrust so keeping at reverse idle is a good idea when clearing at high speed.

[mcdhu]

A320 FCOM (CFM) says:
"AT TAXI SPEED
REVERSERS.........STOW
When the aircraft reaches the taxi speed, and before it leaves the runway, stow the reversers.'

[Rostermouse]

See lomapaseo's note above - it's not just 4-eng aircraft or wide bodies that risk ingestion from FOD; all aircraft are at a greater risk of FOD ingestion when on taxiways than on runways for the simple fact that they are not usually as well-maintained/inspected in many parts of the world. Engine intakes on a low-mounteed a/c are much closer to the grass/dirt on a taxiway than on a 45m-wide runway. I take your point that there's little point adding fwd thrust if still braking, but by the time you vacate the runway you should be going slow enough that adding a little fwd thrust is not a threat.

[yoko1]

Depends on the aircraft. What guidance does the manufacturer provide?

[Sidestick_n_Rudder]

IIRC Airbus recommends to stow the reversers before leaving the runway due to FOD. I’m too lazy to look it up for you, but it’s clearly written somewhere in the FCTM.

[Uplinker]

Yes. Airbus say to stow reversers when reaching 70 kts to avoid FOD ingestion.

With some stopping issues following failures, they say you can use reversers all the way down to 0, (obviously increased FOD risk, but deemed acceptable in such circumstances).

[5420N]

Do you have a reference for that?

[easymxp]

In my OM we have as a reference to stow at taxi speed, there’s a limitation regarding snow on the runway.
A part from that I normally see also many Training Captain keeping rev idle while vacating on a RET and only at a low speed (usually around 10kts before the turn after the RET) stowing reverse. It’s really rare on a RET have reverse stowed before leaving the rwy

[Max Angle]

Yes. Airbus say to stow reversers when reaching 70 kts to avoid FOD ingestion
Idle reverse by 70kts, not stowed at 70.

[Check Airman]

What's more troubling is the person who goes from max reverse to forward idle at once. Absolutely no need for that.

Thanks for the FCOM reference that says to store them before vacating, and at taxi speed. Unfortunately the reality is that if we slowed to taxi speed before leaving the runway every time, ATC would quickly get annoyed.

[krismiler]

Most major airports have high speed exits at a 45' angle which you can take at 60 kts depending on aircraft type. A 90' turn would require slowing down to around 10 kts. Some airports monitor runway occupancy time and may follow up if you are way in excess of the expected time without good reason.

[Uplinker]

I don’t know if we are allowed to copy and paste from manufacturer’s manuals, so Moderators please edit if necessary:

From Airbus FCTM (A320) SOPs/ Landing/ Deceleration:

REVERSE THRUST EFFICIENCY
Thrust reversers are more efficient at high speeds: The flight crew must select reverse thrust immediately after main landing gear touchdown.

Below 70 kt, thrust reversers efficiency rapidly decreases. Below 60 kt with REV MAXselected, engine stall may occur. Therefore, it is recommended to reduce the reverse thrust to REV IDLE at 70 kt, and keep REV IDLE until taxi speed.

However in an emergency case, the flight crew must keep REV MAX until full-stop of the aircraft.

At taxi speed, and not above, stow the thrust reversers before leaving the runway, in order to avoid foreign object ingestion.

[compressor stall]

Uplinker - Folk here are in agreement with the FCTM. Your post 9 isn't. REV IDLE is not stowed.

[Uplinker]

Yes, I was sloppy with my terminology. Apologies. :ok:
.

[PapaEchoIndia]

Here’s the FCOM reference

AT TAXI SPEED REVERSERS................................................... ............................................................ .............STOW
L2 ‐ When the aircraft reaches the taxi speed, and before it leaves the runway, stow the reversers.

PRO-NOR-SOP-19 P 3/8

[Black Pudding]

Idle reverse by 70kts, not stowed at 70.

I agree with Max Angle.

I was under the impression it’s reduce from max to idle at 70kts and cancel reverse at taxi speed.

An Interesting question is this, which speed reference are you using, GS off the ND or IAS off the PFD .

[5420N]

IAS is what we use (large airbus operator).

[tdracer]

Absolutely - the risk of re-ingestion and FOD is primarily related to airspeed, not ground speed.

[Smythe]

Does anyone here have an opinion with regard to keeping reversers at idle while vacating the runway after landing when the aircraft is still decelerating (i.e. entering the taxiway). Any possible risks associated with doing this?

What is your airline SOP,?...rev thrust or braking?

Aside from all of the FOD risks noted above, this is an engine cycle that is counted for maintenance. Most airlines tend to want to reduce rev thrust cycles and time, to reduce maintenance cycles on the engines.

Brakes/replacement are far cheaper than engines.....

[compressor stall]

Yes, but more than one airline found that the money saved was negated by some order(s) of magnitude by having an aircraft off the end of the runway in the greenery.

[bill fly]

Aircraft type doesn’t affect the issue too much here. One problem is that in winter with runway conditions reported, very often the turn off taxiways can be much more slippery.
Idle reverse until taxy speed (a very slow taxy speed) is a good idea.
Out in the sticks in summer FOD is the problem, so as long as she brakes OK, stow the reverse.

[Altcrznav]

We're to be fully out of reverse by 60 kts.

As many have mentioned, you risk FOD ingestion keeping them out leaving the runway.

[Check Airman]

I dream for a day when fleet managers stop making up their own procedures.

[InSoMnIaC]

Aircraft type doesn’t affect the issue too much here. One problem is that in winter with runway conditions reported, very often the turn off taxiways can be much more slippery.
Idle reverse until taxy speed (a very slow taxy speed) is a good idea.
Out in the sticks in summer FOD is the problem, so as long as she brakes OK, stow the reverse.

aircraft type does affect the issue quite a bit. The lower the engines and the further they are mounted from the fuselage, the higher the effect of FOD. If its too slippery to be taking a RET at high speed then slow it right down on the runway before vacating. Just tell ATC about it.

[Tomaski]

I've seen a handful of mostly corporate types with high tail mounted engines using reverse on taxiways to manage speed.

[Vessbot]

If its too slippery to be taking a RET at high speed then slow it right down on the runway before vacating. Just tell ATC about it.


That you'll be slowing to a safe speed before turning, is the type of obvious and unnecessary statement that we should not be clogging frequencies with. Like that we won't be taking off overweight or flying slower than stall speed. Duh.

ATC should know that planes have to slow down more for turns when it's slippery out; and if they don't, they'll figure it out quickly enough.

[tdracer]

What is your airline SOP,?...rev thrust or braking?

Aside from all of the FOD risks noted above, this is an engine cycle that is counted for maintenance. Most airlines tend to want to reduce rev thrust cycles and time, to reduce maintenance cycles on the engines.

Brakes/replacement are far cheaper than engines.....

At least in the Boeing world, most of what you wrote is simply wrong. Deploying the reverser is not counted as an 'engine cycle' - only a takeoff is counted as an engine cycle. Max reverse N1 is significantly lower than max climb, so it's not really taking anything significant out of the engine, and FOD damage risk is almost non-existent above 80 knots. It is counted as a reverser cycle, but the Boeing MPD tasks assume one reverser cycle per flight cycle so in most cases you'll be doing the reverser maintenance regardless. According to the Boeing R&M types, appropriate use of the reversers on the 777 saves ~$100 per landing in total maintenance costs (not to mention the costs of going off the end). Brakes aren't cheap either.
If you respect the FCOM recommendations on reverser usage - getting them to idle by 60 knots, and stowing by taxi speed, the risk of re-ingestion and associated engine damage are minimal.
The key is to respect the FCOM recommendations - reverse below 60 knots doesn't do much aside from killing the forward idle thrust - so there is really no reason to use them unless getting the aircraft stopped in time is not a sure thing (in which case abusing the reversers is probably preferable to abusing the airframe).

[bill fly]

aircraft type does affect the issue quite a bit. The lower the engines and the further they are mounted from the fuselage, the higher the effect of FOD. If its too slippery to be taking a RET at high speed then slow it right down on the runway before vacating. Just tell ATC about it.


Well taking a turn off at high speed wasn’t what I discussed - rather the difference between icy conditions, where a taxiway may well not be so well deiced as a runway - and not.
In icy conditions you will use as much of the runway as necessary to decelerate and won’t be trying for an early exit.
If you are prepared by having the reverser in idle, you are in better shape to react to this not uncommon case - particularly if you are first landing after RW opening... The airport ties hard to keep/get the runway open and taxy ways come second.
Generally under such conditions there is less risk of stone ingestion, but snow can be blown loose.

[InSoMnIaC]

That you'll be slowing to a safe speed before turning, is the type of obvious and unnecessary statement that we should not be clogging frequencies with. Like that we won't be taking off overweight or flying slower than stall speed. Duh.

ATC should know that planes have to slow down more for turns when it's slippery out; and if they don't, they'll figure it out quickly enough.


Get off your high Horse buddy. If you don’t have any thing constructive to add then I suggest you keep your negativity to yourself.

It is quite reasonable to advise ATC When they need you to expedite vacating. Or there is guidance in the AIP advising you to use a particular exit which you cannot make or requiring you to vacate within a number of seconds after landing (eg in china).

[Centaurus]

While training crews in Asia who were used to their company procedures (not necessarily Boeing FCTM procedures), it was noticed they tended to completely cancel reverse thrust at the 60 knots call during the landing run. At the call of 60 knots, they would slam the reverse thrust levers fully down from full reverse (Boeing 737). This would cause the aircraft to momentarily accelerate down the runway while the pilot was still also applying the brakes. The reason being the N1 would be still running down through around 60% N1 when the reverser lights went out; thus giving momentarily significant forward thrust.

It wasn't until the English second language pilots were advised to carefully read (and understand) the FCTM instructions about the need to allow the N1 to reach idle reverse before cancelling, that the penny dropped they were doing it all wrong.

It got me thinking about landing with loss of all hydraulic braking capability - rare though that possibility could be, of course. The scenario in the simulator was concerned with the use of reverse thrust and the aircraft managing to stop still in full reverse right at the end of the safety area with a nasty drop at the end. How do you cancel reverse when stopped without the residual forward thrust inherent with cancellation from full reverse, trickling the aircraft over the cliff?

OK - I confess it is a bit far fetched but sometimes a bit of lateral thinking doesn't do you any harm; especially if there is nothing in the book about such a non-normal. And neither does there need to be.

Answer? At the moment the aircraft stops right at the end (your lucky day) cut both start levers while the engines are still at full reverse. With a bit of luck, there will be little or no forward thrust to roll you over the cliff with no brakes.

Writer quickly exits stage left..

[Airmann]

Answer? At the moment the aircraft stops right at the end (your lucky day) cut both start levers while the engines are still at full reverse. With a bit of luck, there will be little or no forward thrust to roll you over the cliff with no brakes.


Or just go to idle reverse and let the plane back up a before cancelling

[hans brinker]

While training crews in Asia who were used to their company procedures (not necessarily Boeing FCTM procedures), it was noticed they tended to completely cancel reverse thrust at the 60 knots call during the landing run. At the call of 60 knots, they would slam the reverse thrust levers fully down from full reverse (Boeing 737). This would cause the aircraft to momentarily accelerate down the runway while the pilot was still also applying the brakes. The reason being the N1 would be still running down through around 60% N1 when the reverser lights went out; thus giving momentarily significant forward thrust.

It wasn't until the English second language pilots were advised to carefully read (and understand) the FCTM instructions about the need to allow the N1 to reach idle reverse before cancelling, that the penny dropped they were doing it all wrong.

It got me thinking about landing with loss of all hydraulic braking capability - rare though that possibility could be, of course. The scenario in the simulator was concerned with the use of reverse thrust and the aircraft managing to stop still in full reverse right at the end of the safety area with a nasty drop at the end. How do you cancel reverse when stopped without the residual forward thrust inherent with cancellation from full reverse, trickling the aircraft over the cliff?

OK - I confess it is a bit far fetched but sometimes a bit of lateral thinking doesn't do you any harm; especially if there is nothing in the book about such a non-normal. And neither does there need to be.

Answer? At the moment the aircraft stops right at the end (your lucky day) cut both start levers while the engines are still at full reverse. With a bit of luck, there will be little or no forward thrust to roll you over the cliff with no brakes.

Writer quickly exits stage left..

Had this happen in a light jet, Citation bravo. Has a seperate hydraulic system for the brakes and we lost all the fluid. I diverted to the longest runway, used the reverse to slow down to a complete stop. I had my hand on the emergency nitrogen powered emergency brake in case I needed it but wanted to avoid using it if I didn't have to because of the extra maintenance. So after I stopped I felt it started moving backwards, so I selected forward idle on one of the engines, stopped, shut both down, and we stood still long enough for the fire department to chock the nosewheel.

[Tomaski]

Quite a while back, some airliners with tail mounted engines (DC-9/MD-80, 727’s, certain Fokkers) routinely used reverse to “power back” off a gate to save cost of having extra tugs. I think someone eventually figured out that the cost of fuel and wear on the engines was more than the cost of the tug.

[PENKO]

If you do not stow the reversers upon reaching the taxiway you risk ingesting FOD and other stuff, as an A319 crew found out when they exited the runway in wintery conditions with the reversers still deployed. The low swung engines ingested de-icing chemicals, which caused smoke en fumes in the cabin, which led to an emergency evacuation initiated by the cabin crew (!).
Report: Easyjet A319 at Belfast on Jan 6th 2011, taxiway de-icing prompts evacuation (http://avherald.com/h?article=44fe403b)


Anyway, Airbus FCTM says: stow reversers before leaving the runway to avoid ingesting FOD. Seems pretty sensible to me.

[Centaurus]

We're to be fully out of reverse by 60 kts.
Is that the manufacturer's recommendation? Depends on aircraft type. For example B737 FCTM states: "Maintain reverse thrust as required, up to maximum, until the airspeed approaches 60 knots. At this point start reducing the reverse thrust so that the reverse thrust levers are moving down at a rate commensurate with the deceleration rate of the airplane. The thrust levers should be positioned to reverse ideal by taxi speed, then full down after the engines have decelerated to idle. Reverse thrust is reduced to idle between 60 knots and taxi speed to prevent engine exhaust re-ingestion and to reduce the risk of FOD. It also helps the pilot maintain directional control in event a reverser becomes inoperative. The PM should call out 60 knots to assist the PF in scheduling reverse thrust."

You can't get it more clearer than that.

[SaulGoodman]

Boeing 4-holer. Idle rev at 70 kts. Stow reversers before vacating the runway.

[goeasy]

Someone needs to tell the man writing the Airbus manuals, that most airports won’t accept you being at taxi speed before leaving the runway. It defeats the whole purpose of high speed exits. And icy conditions aside, I believe the HS exits were well swept by the previous aircraft vacating!

[Check Airman]

Most airports won't accept their deceleration schedule either. We make it work though.

[Escape Path]

I think Airbus is pretty clear that we should have the reversers stowed before leaving the runway, whether high speed or low speed turn-off...

Anyone care to enlighten a Caribbean pilot on why they should be stowed at a lower speed when on a snow covered runway (25 vs 30 kts)? FCOM says so...

[Fursty Ferret]

According to Airbus, using reverse below 25kts causes snow to recirculate into the engine inlet and potentially cause a flame-out. Not noticed this myself and have selected idle reverse on a snow-covered taxiway when wheel brakes were doing absolutely nothing to control the speed. Weirdly there's nothing in the FCOM prohibiting reverse use on a taxiway, although it may be that it falls into the same warning category of "do not land the aircraft upside down" or "make sure that both wings are firmly attached before flying".

Edit: you might be misinterpreting the FCOM. I think in this case Airbus wants the reverse stowed at slightly higher than normal speeds.

[sonicbum]

https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/816x248/screenshot_2020_07_29_at_15_21_43_b2e20bd1e8c3da7571bf951409 a810c215b173c6.png

[FlightDetent]

Escape Path the 30 kt number is not in the OEM print. Same as FF above, I interpret the 25 kt guidance for snow-covered runways as a suggestion to stow the REV sooner.

[Escape Path]

Escape Path the 30 kt number is not in the OEM print.

I guess that’s where the confusion starts from. Our FCOM says to “stow reversers when reaching taxi speed”, then it says that “speeds below 30 kts are considered taxi speeds”. But then it says that on snow covered runways they should be stowed by 25 kts, giving the impression that they should actually be stowed at a slower speed (I.e. later) than on an uncontaminated runway, which didn’t make sense to me.

Thank you all for your inputs.

[Check Airman]

I guess that’s where the confusion starts from. Our FCOM says to “stow reversers when reaching taxi speed”, then it says that “speeds below 30 kts are considered taxi speeds”. But then it says that on snow covered runways they should be stowed by 25 kts, giving the impression that they should actually be stowed at a slower speed (I.e. later) than on an uncontaminated runway, which didn’t make sense to me.

Thank you all for your inputs.
25 vs 30kt? the only way to tell the difference between those 2 with any accuracy is by looking at the ND. In the grand scheme of things, if the person checking you is going to harp on that, he/she probably can't see the forest for the trees.

[blind pew]

Nearly ran off the runway at Gothenburg after the preceding airbus left their reverse on until clearing the ice covered runway which had been warm sanded. The reverse melted the top layer of ice which allowed the sand to sink and refroze which left us applying emergency reverse until the engines surged. Clue underwear change.

[dixi188]

Nearly ran off the runway at Gothenburg after the preceding airbus left their reverse on until clearing the ice covered runway which had been warm sanded. The reverse melted the top layer of ice which allowed the sand to sink and refroze which left us applying emergency reverse until the engines surged. Clue underwear change.
I guess that was in the stove pipe engine era and not todays fan engines.
Alwasy found GOT interesting in the winter. Saw a BusyBee F27 going sideways when taxiing on an icy ramp and then I slipped and fell getting off our aircraft.

[jmmoric]

Aircraft being swung around by a light breeze taxiing on a icy ramp, pilots yelling that the follow me has to continue ahead cause he cannot brake, aircraft doing run up on the runway due ice on the ramp, firefigthers helping pulling C172 back on the taxiway after it slid off....

Oh, and controllers doing 360'ies in cars on the empty ramp :E

[Escape Path]

Check Airman no snow in these Caribbean latitudes, nor any of our destinations, so no check on that. I was just interested in knowing the logic behind the numbers hehe

I wasn’t being able to get my head around a 5kt difference to stow the reversers, but it’s clear now that all they want is for you to stow them a little earlier than on a dry runway.

[Check Airman]

Ah. That makes sense. I don’t know why I assumed it was in conjunction with a checking event. It’s nice to need only academic knowledge of snow season :)

[blind pew]

Was it JAL that didn't like the icy taxiway and rather than use engine thrust shut all 4 down and was blown down an embankment breaking the aircraft..
Had a mate manoeuvre a dc8 after ice rain without brakes or steering using the motors.

[amc890]

. Our FCOM says to “stow reversers when reaching taxi speed”, then it says that “speeds below 30 kts are considered taxi speeds”. But then it says that on snow covered runways they should be stowed by 25 kts, giving the impression that they should actually be stowed at a slower speed (I.e. later) than on an uncontaminated runway, which didn’t make sense to me.

Thank you all for your inputs.
A possible interpretation of the first sentence is as it reads, not “stow reversers when reaching maximum taxi speed” just whatever taxi speed you desire.

[ImbracableCrunk]

https://cimg4.ibsrv.net/gimg/pprune.org-vbulletin/500x2000/thrust_reverser_info_tall_copy_e7b0928bc114c6cb30c2672554284 d2f0c7c4bf8.png

[MD83FO]

One way, is to find out what the safety department has the parameter set at in the flight data analysis.
hopefully it’s a value set by airbus in my case, and not the operator.

[Fursty Ferret]

https://cimg8.ibsrv.net/gimg/pprune.org-vbulletin/816x248/screenshot_2020_07_29_at_15_21_43_b2e20bd1e8c3da7571bf951409 a810c215b173c6.png

Interesting. We spent quite some time on the subsequent flight searching for a specific prohibition against reverse in the FCOM and it was right in front of us the whole time. :ugh:

[misd-agin]

Stowing reversers with N1's still spinning above idle N1 is probably the most common SOP shortcoming I see.

[sonicbum]

I guess this is aircraft/engine related. What type are thinking about ?

[NGjockey]

Question 1: Has anyone heard of a procedure on the 747 to stow the inboard reversers first during deceleration in order to avoid debris being blown up and sucked into the outboard engines?

Question 2: The discrepancy between what the FCOM says and what I observe in real life is quite drastic. According to the FCOM, the movement of the reverse thrust levers from full reverse to the idle detent should be initiated latest by 60 knots. When the engines have decelerated to reverse idle, the reverse thrust levers should be positioned to the full down (forward thrust = stowed) position. That would mean that the reversers would be fully stowed at around 30 - 40 knots, just before reaching taxi speed. Does anyone with experience and maybe some technical background on the 747 have any information about the possibility of engine damage because of debris ingestion caused by reaching the fully stowed position at low speeds instead of higher speeds (e.g. around 60 knots)?

[oceancrosser]

Thanks ImbracableCrunk, good picture to show to those who slam the thrust levers into forward thrust at 60 kts :ugh:
misd-again, agreed!

[Check Airman]

Bonus points if they go from max reverse to fwd idle in one motion. :D

[40KTSOFFOG]

I suggest a quick read of this incident report (AAIB 5/2012) should answer many of the questions raised.

https://assets.publishing.service.gov.uk/media/5422eeceed915d1374000241/Airbus_A319-111_G-EZFI_05-12.pdf

[Check Airman]

Thanks for this. I’ve used reverse while on the taxiway after vacating. Not sure down to what speed though- I doubt as low as 15kt. I’ll certainly keep this incident in mind for the winter though.

[misd-agin]

I guess this is aircraft/engine related. What type are thinking about ?

It is related to aircraft/engine type. I’ve seen it in the MD-80, 727, 737-800, 757, 767, 777, A300, A320, A330.

I’m starting to think it’s not the engines fault.

[ImbracableCrunk]

I'm not certain about other types, but it is SOP for the 737CL and NG.

[Pugilistic Animus]

IIRC ( Although it's probably forbidden by most company's SOPs) the 757 was certified for a power back but I think you need an NTO for it. I don't know about the 767.

[Fursty Ferret]

Thanks for this. I’ve used reverse while on the taxiway after vacating. Not sure down to what speed though- I doubt as low as 15kt.

"This thing seems a lot more sluggish than usual- oh, wait, reversers still out".

Ahem. Not that I've ever done that.

[tdracer]

We demonstrated the capability on the 767, but it was never an approved procedure. To use it, the operator would have to make a specific request to Boeing, and Boeing would issue an NTO. I don't think it was ever actually done out in the real world. Basically for emergency use - e.g. there is a hurricane coming and you need to get the hell out of Dodge before it arrives but don't have a tug available.
I suspect the 757 was the same way but I don't know that for a fact.

[172_driver]

IIRC ( Although it's probably forbidden by most company's SOPs) the 757 was certified for a power back but I think you need an NTO for it. I don't know about the 767.

Or you just do it, and hope it won't end up on Youtube! ;)

https://www.youtube.com/watch?v=lqZ83gJc7DE&t=42s