Airbus aurtobrake "decel" call
Thread Starter
Airbus aurtobrake "decel" call
hey all,
airline number 5 and I am now totally confused as to what the decal call indicates after touchdown in the 320/330 family.
FCOM and FCTM indicate that the decal call is based upon the speed trend decreasing and the crew feeling the aircraft slow. The call is not based on the illumination of the decal light as it may or may not illuminate depending on the rate of deceleration.
My previous carriers the call was "decal" if the decal light came on or "no decal" if it did not come on.
My question is, if I am correct and the call is based simply on the speed decaying and the crew sensing the aircraft slowing, then:
1. Why make such a call if deceleration at idle power is virtually guaranteed and
2. Where is the error trap if we forget to arm the auto brake? The "decal" call could erroneously lead the PF into thinking the aircraft is auto braking.
Regards
airline number 5 and I am now totally confused as to what the decal call indicates after touchdown in the 320/330 family.
FCOM and FCTM indicate that the decal call is based upon the speed trend decreasing and the crew feeling the aircraft slow. The call is not based on the illumination of the decal light as it may or may not illuminate depending on the rate of deceleration.
My previous carriers the call was "decal" if the decal light came on or "no decal" if it did not come on.
My question is, if I am correct and the call is based simply on the speed decaying and the crew sensing the aircraft slowing, then:
1. Why make such a call if deceleration at idle power is virtually guaranteed and
2. Where is the error trap if we forget to arm the auto brake? The "decal" call could erroneously lead the PF into thinking the aircraft is auto braking.
Regards
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Notwithstanding the number of airlines you have worked for, I would follow their SOP's while operating for them.
The call is "decel" meaning deceleration. Perhaps "Decal" is a typo.
From the FCTM, the green DECEL light comes on at 80% of the selected rate. So, you may be decelerating long before the green DECEL indication. It is not therefore an indication of autobrake operation.
From my company SOP's, "The deceleration is felt by the flight crew and confirmed by the speed trend on the PFD. The deceleration may also be confirmed by the DECEL light (if autobrake is on).
So to answer your question, yes, it is based on crew sensing the deceleration. I wouldn't say that idle power guarantees a deceleration ( however I accept it would be rare not to) but you may encounter aquaplaning on occasion and need to announce the state of the aircraft with respect to braking and decelerating. It's all good situational awareness and crew cooperation/crm.
Autobrake does not relieve the pilot of the responsibility of achieving a safe stop wthin the available runway length.
Also, proper briefings should cover the use of autobrake and hopefully mitigate any misunderstandings.
Hope this helps.
The call is "decel" meaning deceleration. Perhaps "Decal" is a typo.
From the FCTM, the green DECEL light comes on at 80% of the selected rate. So, you may be decelerating long before the green DECEL indication. It is not therefore an indication of autobrake operation.
From my company SOP's, "The deceleration is felt by the flight crew and confirmed by the speed trend on the PFD. The deceleration may also be confirmed by the DECEL light (if autobrake is on).
So to answer your question, yes, it is based on crew sensing the deceleration. I wouldn't say that idle power guarantees a deceleration ( however I accept it would be rare not to) but you may encounter aquaplaning on occasion and need to announce the state of the aircraft with respect to braking and decelerating. It's all good situational awareness and crew cooperation/crm.
Autobrake does not relieve the pilot of the responsibility of achieving a safe stop wthin the available runway length.
Also, proper briefings should cover the use of autobrake and hopefully mitigate any misunderstandings.
Hope this helps.
Last edited by Rubber Dog; 29th Sep 2014 at 07:12.
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It is not possible to mistake auto brake application with idle power decelaration because the anti skid action of brake release gives a distinct feeling of of acceleration followed by decelaration which is not there when there is no braking. You physically feel it.
Thread Starter
“I would follow their SOP's while operating for them.”
Indeed, always have and always will.
“Perhaps "Decal" is a typo.”
Not a typo so much as a sneaky IPAD auto correct that I was unaware of.
“Auto brake does not relieve the pilot of the responsibility of achieving a safe stop wthin the available runway length.”
Yep, noted and very obvious, as per FCOM and common sense.
“Also, proper briefings should cover the use of auto brake and hopefully mitigate any misunderstandings.”
True, but after a 15 hour sector landing at o’dark thirty, mistakes are made. There have been several runway over runs as a result of the crew forgetting to arm the auto brake followed by a lack of callout to alert the PF as such.
My point is, calling “decel” simply based on a speed trend and physical sensation should be obvious to both pilots, BUT does not provide an error trap in the case of forgetting to arm the auto brake.
Indeed, always have and always will.
“Perhaps "Decal" is a typo.”
Not a typo so much as a sneaky IPAD auto correct that I was unaware of.
“Auto brake does not relieve the pilot of the responsibility of achieving a safe stop wthin the available runway length.”
Yep, noted and very obvious, as per FCOM and common sense.
“Also, proper briefings should cover the use of auto brake and hopefully mitigate any misunderstandings.”
True, but after a 15 hour sector landing at o’dark thirty, mistakes are made. There have been several runway over runs as a result of the crew forgetting to arm the auto brake followed by a lack of callout to alert the PF as such.
My point is, calling “decel” simply based on a speed trend and physical sensation should be obvious to both pilots, BUT does not provide an error trap in the case of forgetting to arm the auto brake.
True, but after a 15 hour sector landing at o’dark thirty, mistakes are made. There have been several runway over runs as a result of the crew forgetting to arm the auto brake followed by a lack of callout to alert the PF as such.
Two pìlots are not monitoring the rate of deceleration on the landing roll and putting an overrun down to a misunderstanding about what decel means? PF doesn't arm the auto brake and just lets the aircraft go off the runway......
Please tell me I have read this wrong......
Thread Starter
I know of 2 A320's that took a lunch in the grass and a 744 that did the same as a result of the crew not becoming aware of the fact that the auto brake had dropped out. No major carnage in these accidents occurred except serious bent metal.
They were not the result of misunderstanding of what decel means, they were the result of firstly not noticing that the auto brake was not doing its job followed by a lack of support call to advise the PF as such.
This is why I am puzzled as to why we do not have an SOP that provides information as to the status of the auto brake on rollout but we do have one that provides information that is plainly freakin obvious.
They were not the result of misunderstanding of what decel means, they were the result of firstly not noticing that the auto brake was not doing its job followed by a lack of support call to advise the PF as such.
This is why I am puzzled as to why we do not have an SOP that provides information as to the status of the auto brake on rollout but we do have one that provides information that is plainly freakin obvious.
They were not the result of misunderstanding of what decel means, they were the result of firstly not noticing that the auto brake was not doing its job followed by a lack of support call to advise the PF as such.
How does PF defend such shortcomings? 'Sorry for letting the aircraft go off the runway, but PNF didn't say I should brake so I didn't!'
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Pilot who is looking out to keep it straight but cannot judge his decelaration, does not notice the change in runway light colour towards the end should not be in the cockpit.
Thread Starter
“So PF just sits there fat dumb and happy as the aircraft goes off the runway?”
No, I suspect the pilot sits there fat dumb and happy in the early stages of the landing roll assuming the auto brake kicks in and by the time he realizes it isn’t going to, he presses the pedals to the floor at a point that is too late to prevent the over run.
“I put it to you that ANY excursion is serious and potentially life threatening and not as you put it in rather a blasé and cavalier 'no major carnage'.”
I agree, I am not sure how you deduce that I am “blasé” and “cavalier”; perhaps my sense of humor or lack thereof can be blamed. Over runs are often fatal.
“How does PF defend such shortcomings? 'Sorry for letting the aircraft go off the runway, but PNF didn't say I should brake so I didn't!'”
No, I suspect that’s not how it would unfold at all however that’s why we have support calls. The same argument could be made about every pilot transgression. An altitude bust for example. “I flew right through the level because blogs didn’t call one to go”.
“Pilot who is looking out to keep it straight but cannot judge his decelaration, does not notice the change in runway light colour towards the end should not be in the cockpit.”
Perhaps you are right although I have never been in a possible over run situation so I am not going make such an accusation however it should be noted that many runway lights don’t change color and heavy rain in such a situation could make it difficult to accurately judge.
Guys, I was simply asking a question to survey what other operators of Airbus aircraft do. I have never left the pavement in a jet and have never overlooked the selection of auto brake.
BUT it has happened several times at least so its something worth considering.
That’s all.
No, I suspect the pilot sits there fat dumb and happy in the early stages of the landing roll assuming the auto brake kicks in and by the time he realizes it isn’t going to, he presses the pedals to the floor at a point that is too late to prevent the over run.
“I put it to you that ANY excursion is serious and potentially life threatening and not as you put it in rather a blasé and cavalier 'no major carnage'.”
I agree, I am not sure how you deduce that I am “blasé” and “cavalier”; perhaps my sense of humor or lack thereof can be blamed. Over runs are often fatal.
“How does PF defend such shortcomings? 'Sorry for letting the aircraft go off the runway, but PNF didn't say I should brake so I didn't!'”
No, I suspect that’s not how it would unfold at all however that’s why we have support calls. The same argument could be made about every pilot transgression. An altitude bust for example. “I flew right through the level because blogs didn’t call one to go”.
“Pilot who is looking out to keep it straight but cannot judge his decelaration, does not notice the change in runway light colour towards the end should not be in the cockpit.”
Perhaps you are right although I have never been in a possible over run situation so I am not going make such an accusation however it should be noted that many runway lights don’t change color and heavy rain in such a situation could make it difficult to accurately judge.
Guys, I was simply asking a question to survey what other operators of Airbus aircraft do. I have never left the pavement in a jet and have never overlooked the selection of auto brake.
BUT it has happened several times at least so its something worth considering.
That’s all.
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oicur12.again
If there is threat perception then there will a plan to trap the error and that should be right at the approach briefing stage by selecting appropriate level of braking and asking for more vigilance on the aspect of deceleration by PNF and in case of slightest doubt taking over manual braking. Most of the incidence we hear these days are due to total lack of monitoring of automation be it ATHROTTLE, altitude capture or flight path. There is no cure for that.
If there is threat perception then there will a plan to trap the error and that should be right at the approach briefing stage by selecting appropriate level of braking and asking for more vigilance on the aspect of deceleration by PNF and in case of slightest doubt taking over manual braking. Most of the incidence we hear these days are due to total lack of monitoring of automation be it ATHROTTLE, altitude capture or flight path. There is no cure for that.
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My outfit SOP is to call "auto brake off" as part of the PNF calls after touchdown to ensure the PF remembers to use manual braking for the exact reason OI is talking about.
Kick the tires - you ought read more about the screw ups happening in airline ops if braking issues are the ones that set your hair on fire. what about touching down 1200m into a short rain soaked runway with 15 knots up the date at max landing weight or landing a glass jet with all of the GPS/NAV/FD bells and whistles at the wrong airport?????
Did they just sit there and watch it happen?
Kick the tires - you ought read more about the screw ups happening in airline ops if braking issues are the ones that set your hair on fire. what about touching down 1200m into a short rain soaked runway with 15 knots up the date at max landing weight or landing a glass jet with all of the GPS/NAV/FD bells and whistles at the wrong airport?????
Did they just sit there and watch it happen?
Huh?
The PNF calls Autobrake off........?
So is that a statement of observation or an instruction to the PF?
Why disconnect the Autobrake so early?
The observation of the Decel light and the Aircraft slowing appropriately should be sufficient for the commander to observe all is ok. ( I say commander because after all it is his responsibility no matter who is driving the ship )
Then later the PF advises the PM "manual braking" just to let him know what is going on.
Why complicate it?
Worked for my mob this way on all types ( A and B ) for 20+ years and none of our Aircraft have had any issues...
The PNF calls Autobrake off........?
So is that a statement of observation or an instruction to the PF?
Why disconnect the Autobrake so early?
The observation of the Decel light and the Aircraft slowing appropriately should be sufficient for the commander to observe all is ok. ( I say commander because after all it is his responsibility no matter who is driving the ship )
Then later the PF advises the PM "manual braking" just to let him know what is going on.
Why complicate it?
Worked for my mob this way on all types ( A and B ) for 20+ years and none of our Aircraft have had any issues...
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Hi there,
my 2 cents: PF is PF even during landing (unless CDR takes over for whatever reason), so he/she is responsible for the proper braking, whatever the PM call is.
"Decel / No Decel" is indeed a very good PM call for the braking effectiveness of the bird on the rwy, despite the green light which is the consequence of the proper braking rate.
But, as the golden rule states: if things (autobrake) are not going as expected, (PF) take over.. So jump on the brakes and stop the bird or quickly do the "loss of braking" memory items in case of failure..
Back on topic, I quote the braking feeling and speed trend as a trigger of the "Decel" call for effective braking.
my 2 cents: PF is PF even during landing (unless CDR takes over for whatever reason), so he/she is responsible for the proper braking, whatever the PM call is.
"Decel / No Decel" is indeed a very good PM call for the braking effectiveness of the bird on the rwy, despite the green light which is the consequence of the proper braking rate.
But, as the golden rule states: if things (autobrake) are not going as expected, (PF) take over.. So jump on the brakes and stop the bird or quickly do the "loss of braking" memory items in case of failure..
Back on topic, I quote the braking feeling and speed trend as a trigger of the "Decel" call for effective braking.
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Liking Vilas's comment!
Anyhow, if you base the decel call on the autobrake light, then when you are landing on a contaminated runway, you may end up doing the wrong thing as that light may, or may not come on even when the autobrake is functioning correctly (See FCOM)
So by basing it on speed trend and expected deceleration rate you get a 'professional judgement' whether things are progressing as expected... And remember, both pilots feet are fitted with brake pedals so if it isn't and they aren't, you should!
Anyhow, if you base the decel call on the autobrake light, then when you are landing on a contaminated runway, you may end up doing the wrong thing as that light may, or may not come on even when the autobrake is functioning correctly (See FCOM)
So by basing it on speed trend and expected deceleration rate you get a 'professional judgement' whether things are progressing as expected... And remember, both pilots feet are fitted with brake pedals so if it isn't and they aren't, you should!
