Deploying Thrust Reversers to Dump Lift on Sporty Landings
Discussion
This video cropped up on my YT recommendations - a RyanAir 737 deploying thrust reversers just before touchdown get the aircraft down quickly.
https://www.youtube.com/watch?v=-RO66a_nvus
Just wondering if that is an option in the SOPs when it's sporty, or if the pilot concerned has gone off-message here. Seems a bit risky if you've got to go around. I did think deploying in flight was not possible but apparently if the radalt is reporting <10 feet the aircraft will let them deploy.
Any 737 drivers able to educate me ?
https://www.youtube.com/watch?v=-RO66a_nvus
Just wondering if that is an option in the SOPs when it's sporty, or if the pilot concerned has gone off-message here. Seems a bit risky if you've got to go around. I did think deploying in flight was not possible but apparently if the radalt is reporting <10 feet the aircraft will let them deploy.
Any 737 drivers able to educate me ?
Edited by 48k on Wednesday 20th October 12:30
I am not a pilot, but I have read that the 737 does allow reversers to be opened without weight on wheels.
The only aircraft that I know of that will actually use its reversers in flight is the C5. They can do very steep approaches and to keep their airspeed under control they will use them.
The only aircraft that I know of that will actually use its reversers in flight is the C5. They can do very steep approaches and to keep their airspeed under control they will use them.
They will reduce speed but won't directly affect lift (different kettle of fish on a turboprop) other than through reducing airspeed - only the spoilers actively dump lift and on landing they're activated by a signal from the main undercarriage. I don't know the 737 specifically but usually a proximity switch "weight on wheels" and/or "wheels turning" signal from the anti-skid brake system's sensors trigger the lift dump spoilers.
You can see in this video the thrust reversers are deployed before touch down but the spoilers don't pop up until just after the main wheels have touched the runway.
You can see in this video the thrust reversers are deployed before touch down but the spoilers don't pop up until just after the main wheels have touched the runway.
gotoPzero said:
I am not a pilot, but I have read that the 737 does allow reversers to be opened without weight on wheels.
The only aircraft that I know of that will actually use its reversers in flight is the C5. They can do very steep approaches and to keep their airspeed under control they will use them.
Yes I'm aware there are other aircraft and situations where TRs have been intentionally deployed in flight - one example that springs immediately to mind is the Gulfstream that NASA used to train Space Shuttle pilots. But my question was specifically about commercial ops in an airliner. Deploying TRs to get the wheels on the ground quickly seems a touch...."unusual" The only aircraft that I know of that will actually use its reversers in flight is the C5. They can do very steep approaches and to keep their airspeed under control they will use them.
jamieduff1981 said:
They will reduce speed but won't directly affect lift (different kettle of fish on a turboprop) other than through reducing airspeed - only the spoilers actively dump lift and on landing they're activated by a signal from the main undercarriage. I don't know the 737 specifically but usually a proximity switch "weight on wheels" and/or "wheels turning" signal from the anti-skid brake system's sensors trigger the lift dump spoilers.
You can see in this video the thrust reversers are deployed before touch down but the spoilers don't pop up until just after the main wheels have touched the runway.
Thanks. Yes poor choice of words by me, I'm not referring to spoilers but deploying TRs is going to cause the aircraft to rapidly slow which will "dump" (suddenly reduce) lift across the wing as seen in vid.You can see in this video the thrust reversers are deployed before touch down but the spoilers don't pop up until just after the main wheels have touched the runway.
gotoPzero said:
I am not a pilot, but I have read that the 737 does allow reversers to be opened without weight on wheels.
The only aircraft that I know of that will actually use its reversers in flight is the C5. They can do very steep approaches and to keep their airspeed under control they will use them.
A comment on that clip:- “The Boeing 737's reversers are deployable within 90cm from the ground . The pilot can decide to deploy them before touchdown in wet or windy conditions, so the aircraft has more breakpower at the beginning of the landing roll and avoid big bounces. He didn't do anything wrong, he won't get fired. He just got the aircraft, crew and passangers safely on the ground.”The only aircraft that I know of that will actually use its reversers in flight is the C5. They can do very steep approaches and to keep their airspeed under control they will use them.
ktcanuck said:
Minor point: Thrusts reversers don't dump lift, they control speed.
...as already acknowledged above. Poor choice of words by me.48k said:
Thanks. Yes poor choice of words by me, I'm not referring to spoilers but deploying TRs is going to cause the aircraft to rapidly slow which will "dump" (suddenly reduce) lift across the wing as seen in vid.
Hoping one of the resident commercial pilots will be along soon to actually answer the question. I flew the 737 and yes, you could select reverse around about 5 feet or less above the ground (I don't have the aircraft Ops Manuals to hand, unfortunately).
I've seen them selected maybe only once or twice 'real-world' while still airborne not as a matter of course, but generally down to a small float in the flare, possibly combined with a mental 'commitment' to landing at that point in the flare.
My company procedure (and probably Boeing's) is not to select reverse until you're on the ground. Can't speak for Ryanair, but it's generally the thing to do (not select it), as once the reversers are selected the general rule is you're committed to the landing rollout. ie Committing whilst still airborne is not standard practice - sporty landing, or not . . .
I've seen them selected maybe only once or twice 'real-world' while still airborne not as a matter of course, but generally down to a small float in the flare, possibly combined with a mental 'commitment' to landing at that point in the flare.
My company procedure (and probably Boeing's) is not to select reverse until you're on the ground. Can't speak for Ryanair, but it's generally the thing to do (not select it), as once the reversers are selected the general rule is you're committed to the landing rollout. ie Committing whilst still airborne is not standard practice - sporty landing, or not . . .
Big no no.
One of the many issues is that once you’ve selected reverse thrust you can’t go around so even that low, normally you could still go around and do a ‘baulked landing’ ( where you touch down but take off again) but with reverse thrust deployed you’re committed to landing and stopping.
That near the ground you should be ready to go around and not have your hands on the reversers or worse actually initiating reverse thrust as is happening here.
Perhaps the pilot thought they’d touched down or perhaps it was target fixation during a difficult approach.
The Boeing flight crew training manual makes this perfectly clear on many occasions than you select it after landing and once initiated you can’t go around.
One of the many issues is that once you’ve selected reverse thrust you can’t go around so even that low, normally you could still go around and do a ‘baulked landing’ ( where you touch down but take off again) but with reverse thrust deployed you’re committed to landing and stopping.
That near the ground you should be ready to go around and not have your hands on the reversers or worse actually initiating reverse thrust as is happening here.
Perhaps the pilot thought they’d touched down or perhaps it was target fixation during a difficult approach.
The Boeing flight crew training manual makes this perfectly clear on many occasions than you select it after landing and once initiated you can’t go around.
Lots already covered there. I was surprised it was possible. I was on the 3,4 and 500's and think the levers were locked until the air/ground logic switched.
A320 family need weight on both wheels before they'll deploy but the levers can be selected whilst in the air. But that is against SOP for the reasons mentioned above, it commits you to land because it moves the flaps up a bit.
A320 family need weight on both wheels before they'll deploy but the levers can be selected whilst in the air. But that is against SOP for the reasons mentioned above, it commits you to land because it moves the flaps up a bit.
I wonder why it uses the radalt to unlock reverse thrust and not WOW
(According to http://www.b737.org.uk/powerplant.htm#Reverse_Thru... anyway)
(According to http://www.b737.org.uk/powerplant.htm#Reverse_Thru... anyway)
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