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Idle Reverse while vacating

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Idle Reverse while vacating

Old 13th Jul 2019, 20:16
  #41 (permalink)  
 
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Most airports won't accept their deceleration schedule either. We make it work though.
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Old 28th Jul 2020, 21:56
  #42 (permalink)  
 
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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...
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Old 29th Jul 2020, 09:17
  #43 (permalink)  
 
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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.
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Old 29th Jul 2020, 13:22
  #44 (permalink)  
 
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Originally Posted by Fursty Ferret View Post
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.

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Old 29th Jul 2020, 14:33
  #45 (permalink)  

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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.
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Old 29th Jul 2020, 17:08
  #46 (permalink)  
 
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Originally Posted by FlightDetent View Post
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.

Last edited by Escape Path; 29th Jul 2020 at 17:12. Reason: Failure to apply Grammar for Dummies in real life
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Old 30th Jul 2020, 05:35
  #47 (permalink)  
 
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Originally Posted by Escape Path View Post
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.
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Old 30th Jul 2020, 06:40
  #48 (permalink)  
 
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Escape path

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.
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Old 30th Jul 2020, 09:01
  #49 (permalink)  
 
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Originally Posted by blind pew View Post
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.
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Old 30th Jul 2020, 11:32
  #50 (permalink)  
 
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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
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Old 30th Jul 2020, 16:08
  #51 (permalink)  
 
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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.
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Old 30th Jul 2020, 17:10
  #52 (permalink)  
 
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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
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Old 30th Jul 2020, 18:47
  #53 (permalink)  
 
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747 ANC

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.
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Old 30th Jul 2020, 21:38
  #54 (permalink)  
 
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Originally Posted by Escape Path View Post
. 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.
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Old 31st Jul 2020, 03:19
  #55 (permalink)  
 
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Old 31st Jul 2020, 16:45
  #56 (permalink)  
 
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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.
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Old 1st Aug 2020, 08:24
  #57 (permalink)  
 
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Originally Posted by sonicbum View Post
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.
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Old 1st Aug 2020, 13:32
  #58 (permalink)  
 
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Stowing reversers with N1's still spinning above idle N1 is probably the most common SOP shortcoming I see.
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Old 1st Aug 2020, 14:31
  #59 (permalink)  
 
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Originally Posted by misd-agin View Post
Stowing reversers with N1's still spinning above idle N1 is probably the most common SOP shortcoming I see.
I guess this is aircraft/engine related. What type are thinking about ?
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Old 5th Aug 2020, 10:39
  #60 (permalink)  
 
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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)?



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