Question on A320 Autobrakes selection v runway length
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Question on A320 Autobrakes selection v runway length
What prompts this question is the recent experience of a colleague who was a passenger on a Jetstar A320 flight that landed at an East Coast runway 6000 ft long dry hard surface sea level. He is a former 747, 727 and 737 captain so he is no amateur PPL. Immediately after touch-down there was very severe braking accompanied soon after by the normal sound of full reverse thrust.
Passengers adjacent to him were quite alarmed when they were jerked forward by the aircraft deceleration and several grabbed the back rest of the seat in front of them.
My colleague said he had never experienced such savage braking before and was startled. He assumed it was the autobrakes operating on a high setting or in the case of the A320 Medium setting which is harsh. Soon after he thought he detected the typical slight jerk when the autobrakes were disengaged. Then the aircraft proceeded to taxi quite sedately along the rest of the runway until reaching the end. Meanwhile down the back, passengers calmed down as the aircraft taxied to the terminal, but there was no shortage of muttered bitching comments from frightened passengers wondering what the heavy braking was all about. There was no PA from the crew apologising for the unusually heavy braking. Maybe that was considered normal braking by the pilot ?
The comment by an experienced pilot as a passenger should not be dismissed as a typical cynical remark from a pilot way past his use-by date. In fact he owns his own twin engine aircraft which he flies regularly.
I can understand the reactions of the passengers on that flight. The whole trip had gone smoothly, the service was good and no doubt many were looking forward to a nice time at this well known holiday resort. The touch down was smooth then without warning their comfort turns to momentary fright as the brakes are hit hard. Those few seconds can turn some passengers against travelling on Jetstar in future. Why was the hard braking necessary when the runway length was well beyond the performance limiting length and the runway was dry?
Was it company policy to set the automatic brakes for all landings regardless of excess runway length available? It is my understanding that Qantas for example require the autobrakes to be used on all landings on their 737 fleet even though a runway could be 10,000 ft or greater. Why is this so, I wonder? What happened to giving the captain his discretion to use manual brakes instead of autobrakes. Are crews not to be trusted to use their experience in such basic matters as use of wheel brakes for landing?
In the case in point, what on earth did the captain have to gain in landing performance by using such hard sudden braking on touch down only to coast along the rest of the runway after reducing reverse thrust and reverting to ordinary use of brakes.
If it was company procedure to select autobrakes for landing with runway lengths well in excess of that needed operationally, then surely the minimum setting would be sufficient. Airlines push the advertising publicity line that passenger comfort is paramount. Fine until the point of touch-down, then all bets are off while some pilots put the passengers into the next row of seat in front of them with unnecessary harsh use of brakes - automatic or manually applied. Is this piss-poor airmanship or company mandated procedure?
For normal landings on a dry hard surface, in something like a 737 or A320, is it true that 6000 ft and below is considered a short runway and a maximum performance landing technique is mandatory? And even 8000 ft or more is considered by some the companies as marginal and requiring special considerations Have crews forgotten the art of touch down on correct speed and correct point and the art of judicious gentle braking along with correct use of reverse thrust to bring the aeroplane and its load passengers to a safe stop or turn-off?
Or are we so brain-washed by the manufacturers and perceived risks of litigation that operators cover their backsides to the ridiculous degree on the use of automatics in all our operations, that pilots have lost the basics of how to apply brakes smoothly for passenger comfort? And I am not talking about landing on short wet surface runways that do require positive braking automatic or otherwise?
Passengers adjacent to him were quite alarmed when they were jerked forward by the aircraft deceleration and several grabbed the back rest of the seat in front of them.
My colleague said he had never experienced such savage braking before and was startled. He assumed it was the autobrakes operating on a high setting or in the case of the A320 Medium setting which is harsh. Soon after he thought he detected the typical slight jerk when the autobrakes were disengaged. Then the aircraft proceeded to taxi quite sedately along the rest of the runway until reaching the end. Meanwhile down the back, passengers calmed down as the aircraft taxied to the terminal, but there was no shortage of muttered bitching comments from frightened passengers wondering what the heavy braking was all about. There was no PA from the crew apologising for the unusually heavy braking. Maybe that was considered normal braking by the pilot ?
The comment by an experienced pilot as a passenger should not be dismissed as a typical cynical remark from a pilot way past his use-by date. In fact he owns his own twin engine aircraft which he flies regularly.
I can understand the reactions of the passengers on that flight. The whole trip had gone smoothly, the service was good and no doubt many were looking forward to a nice time at this well known holiday resort. The touch down was smooth then without warning their comfort turns to momentary fright as the brakes are hit hard. Those few seconds can turn some passengers against travelling on Jetstar in future. Why was the hard braking necessary when the runway length was well beyond the performance limiting length and the runway was dry?
Was it company policy to set the automatic brakes for all landings regardless of excess runway length available? It is my understanding that Qantas for example require the autobrakes to be used on all landings on their 737 fleet even though a runway could be 10,000 ft or greater. Why is this so, I wonder? What happened to giving the captain his discretion to use manual brakes instead of autobrakes. Are crews not to be trusted to use their experience in such basic matters as use of wheel brakes for landing?
In the case in point, what on earth did the captain have to gain in landing performance by using such hard sudden braking on touch down only to coast along the rest of the runway after reducing reverse thrust and reverting to ordinary use of brakes.
If it was company procedure to select autobrakes for landing with runway lengths well in excess of that needed operationally, then surely the minimum setting would be sufficient. Airlines push the advertising publicity line that passenger comfort is paramount. Fine until the point of touch-down, then all bets are off while some pilots put the passengers into the next row of seat in front of them with unnecessary harsh use of brakes - automatic or manually applied. Is this piss-poor airmanship or company mandated procedure?
For normal landings on a dry hard surface, in something like a 737 or A320, is it true that 6000 ft and below is considered a short runway and a maximum performance landing technique is mandatory? And even 8000 ft or more is considered by some the companies as marginal and requiring special considerations Have crews forgotten the art of touch down on correct speed and correct point and the art of judicious gentle braking along with correct use of reverse thrust to bring the aeroplane and its load passengers to a safe stop or turn-off?
Or are we so brain-washed by the manufacturers and perceived risks of litigation that operators cover their backsides to the ridiculous degree on the use of automatics in all our operations, that pilots have lost the basics of how to apply brakes smoothly for passenger comfort? And I am not talking about landing on short wet surface runways that do require positive braking automatic or otherwise?
A 6000' runway is plenty for an A320 even at MAX landing weight with tailwind, so runway conditions probably weren't a consideration. Auto brake commands a deceleration rate rather than a specific amount of braking, so if full reverse thrust is used little demand is made on the brakes once deceleration has commenced.
It's possible that they were practicing for more limiting runways, Captain showing a new F/O how quickly the aircraft could be stopped or the F/O practicing his short field technique in an environment were it wouldn't matter if he didn't quite get it right.
It's possible that they were practicing for more limiting runways, Captain showing a new F/O how quickly the aircraft could be stopped or the F/O practicing his short field technique in an environment were it wouldn't matter if he didn't quite get it right.
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Question on A320 Autobrakes selection v runway length
This sounds like the use of Max Autobrake setting (whether intentional or otherwise!) which is indeed harsh. It's meant to be. It is (not recommended for landing but not prohibited either. Medium on an A320 is not harsh at all.
Sounds like a typical MCY landing! Always is a ridiculous argument to land with autorbrakes medium then straight away kick them off and use manual brakes to ease it up to the turning node at the end of the runway. For me if you land on the touchdown zone then auto brake lo will slow you down in plenty of time before the end of the runway. It also means that you are not dealing with hi brake temps on the turnaround.
Back before Sept 11, 2001 when I used to enjoy a few jump seat visits we were on final to runway 16 in Melbourne in a 737. Conversation went like this
"I bet you cant turn off at Echo"
"I bet I can"
Pilot flying then reaches forward, bumps the autobrake up a notch or two.
We turned off at Echo.
Thats always the explanation I have when I have similar experiences now.
Bevan..
"I bet you cant turn off at Echo"
"I bet I can"
Pilot flying then reaches forward, bumps the autobrake up a notch or two.
We turned off at Echo.
Thats always the explanation I have when I have similar experiences now.
Bevan..
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arming all automatic retardation devices is mandatory at jetstar unless otherwise reqd by fcom/qrh procedures or mel dispatch reqmnts
a couple of the older 321s had fierce brakes that were hard to modulate a smooth transition from autobrake to manual braking via peddles esp when commanding a higher braking force than the autobrake was giving
cant speak for the rest of it
poor form if true. thats what sims and type ratings are for.
a couple of the older 321s had fierce brakes that were hard to modulate a smooth transition from autobrake to manual braking via peddles esp when commanding a higher braking force than the autobrake was giving
cant speak for the rest of it
It's possible that they were practicing for more limiting runways, Captain showing a new F/O how quickly the aircraft could be stopped or the F/O practicing his short field technique in an environment were it wouldn't matter if he didn't quite get it right.
Last edited by waren9; 30th Jun 2013 at 08:18.
Mandatory auto brake seems to be a QF group thing. I've been admonished by a QF long haul capt for suggesting that there may be a time and a place for zero auto brake (ie vacating at far end of 3000m runway).
Last edited by compressor stall; 30th Jun 2013 at 09:28.
Mandatory auto brake seems to be a QF group thing. I've been admonished by a QF long haul capt for suggesting that there may be a time and a place for zero auto brake (ie vacating at far end of 3000m runway)
Yeees, so....
So you arm it, then disarm it before landing?
Or you touchdown, then call for it to be disarmed?
Or you touchdown then tap the brakes to disarm?
So you arm it, then disarm it before landing?
Or you touchdown, then call for it to be disarmed?
Or you touchdown then tap the brakes to disarm?
Low LDG weight, auto brake medium & full rev, to a pax with NO upper body restraint device it does feel alarming, does to me when I pax.
AS 'Metro' said it's about a decel rate.
As for auto brake use? Well as per Co Sop's but also some basic airmanship can add to the mix for pax comfort.
Wmk2
AS 'Metro' said it's about a decel rate.
As for auto brake use? Well as per Co Sop's but also some basic airmanship can add to the mix for pax comfort.
Wmk2
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The OP stated that touchdown was smooth. What he doesn't say is how far down the runway that touchdown occurred.
We've all sat bedside someone who sacrificed runway length for an impressively smooth touchdown then stomped on the anchors to pull it up.
Unfortunately the only thing most pax remember is the landing and how long it took to get their bags.
There is a big difference between a smooth landing and a safe landing.
We've all sat bedside someone who sacrificed runway length for an impressively smooth touchdown then stomped on the anchors to pull it up.
Unfortunately the only thing most pax remember is the landing and how long it took to get their bags.
There is a big difference between a smooth landing and a safe landing.
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Since when do the people down the back start questioning the procedures employed by the people up the front?
auto brake medium & full rev, to a pax with NO upper body restraint device it does feel alarming, does to me when I pax.
Last edited by sheppey; 30th Jun 2013 at 12:53.
Originally Posted by Starbear
This sounds like the use of Max Autobrake setting (whether intentional or otherwise!) which is indeed harsh. It's meant to be. It is (not recommended for landing but not prohibited either.
Originally Posted by A320 FCOM
Auto Brake - General
GENERAL
The purposes of this system are :
to reduce the braking distance in case of an aborted takeoff
to establish and maintain a selected deceleration rate during landing, thereby improving passenger comfort and reducing crew workload.
System Arming
The system arms when the crew presses the LO, MED, or MAX pushbutton switch if:
Green pressure is available.
The anti-skid system has electric power.
There is no failure in the braking system.
At least one ADIRS is functioning.
Note
Auto brake may be armed with the parking brake on.
MAX autobrake mode cannot be armed in flight.
GENERAL
The purposes of this system are :
to reduce the braking distance in case of an aborted takeoff
to establish and maintain a selected deceleration rate during landing, thereby improving passenger comfort and reducing crew workload.
System Arming
The system arms when the crew presses the LO, MED, or MAX pushbutton switch if:
Green pressure is available.
The anti-skid system has electric power.
There is no failure in the braking system.
At least one ADIRS is functioning.
Note
Auto brake may be armed with the parking brake on.
MAX autobrake mode cannot be armed in flight.
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Since when do the people down the back start questioning the procedures employed by the people up the front?
Since when do the people down the back start questioning the procedures employed by the people up the front?
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Don't know about the A320. On the 737, use of the optional carbon brakes will nearly always result in heavier application of brakes, part of the regime for efficient use.
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metroman
Make sure you nail the app spd and landing point, 6000' is 1828m, Scheduled LD at 64.5 (mlw) with 10kts TW 1702m.
I doubt I've known a 320 driver who would choose to do that, doable? Yes, but not by choice!
I doubt I've known a 320 driver who would choose to do that, doable? Yes, but not by choice!
We operate into one runway that's less than 2000m, Captains only landing and usually has no tailwind. Full flap, auto brake medium, and max reverse will give a decent arrival provided, as you said, approach speed and touch down point are nailed.
2500m with 10kts tailwind is allowable for our F/Os and can get a bit interesting if they float a bit.
2500m with 10kts tailwind is allowable for our F/Os and can get a bit interesting if they float a bit.