Operationally unnecessary use of autobrakes for landing
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Operationally unnecessary use of autobrakes for landing
With reference to the Boeing 737 Series. That "Bible" the 737 Flight Crew Training Manual states: Use of the autobrake system is recommended whenever the runway is limited, when using higher than normal approach speeds, landing on slippery runways, or landing in a crosswind.
To me that is quite straightforward. And that is there is often no need for use of autobrakes for landings other than the above examples. Common sense would assume that the mention of crosswind implies strong crosswinds and not a few knots. Similarly "when using higher than normal approach speeds" should be taken as seriously high speeds such as all flaps up or partial flap and not simply because of headwind and gust additives which are considered as normal.
It is common to observe pilots using autobrakes for practically every landing regardless of runway lengths far in excess of runway limited. Even then few pilots elect to use less than autobrake 2. Autobrake 1 is almost unheard of. In the simulator we observe pilots using autobrake 2 as a minimum on a 10,000 ft runway and if landing with one engine inoperative they up it to autobrake 3 as if there is some urgency if landing on one engine.
Some time ago, I was involved in training pilots from a large Asian operator where it was company procedure to use Autobrake 2 for every landing. Local culture being what it was, pilots stuck literally to the letter of the law. The simulator session required an all flaps up landing on a limiting runway length. If ever there was an occasion for Autobrake Max this was it. But no, the manual said autobrake 2 for all landings and that is exactly what the pilot used. The result was a significant over-run at high speed off the end of the runway. Culture has a lot to answer for.
Granted, pilots are often constrained by company autobrake policy and have little choice. But one would have thought use of autobrakes increases wear and tear and thus increased cost. McDonald Douglas published an article many years ago called "The High Cost of Hard Braking" where it detailed the cost of each landing with and without autobrakes and where it discussed the lead-footed pilots that cost the company more money by their inappropriate braking technique. It suggested that accurate final approach and touch-down speeds as well as prompt use of reverse thrust often meant that braking use could be minimised. In other words the skill of the pilot in reducing braking to a minimum. The speed at which the brakes were first applied was an important factor in the cost of braking. The higher the speed the more wear and tear. Autobrakes are applied on the instant of touch down (high speed) although they back off to maintain a specific rate of deceleration with use of reverse thrust.
There may be occasions where a turn-off at a specific taxi way is needed operationally but even then judicious combination of reverse and manual braking means braking is at a minimum. Often braking is not needed until below 80 knots where energy requirements, and thus wear and tear, are less. Again, observations in the simulator have shown that pilots addicted to autobraking for whatever reason, when asked to use manual braking, tend to get quite rusty due to lack of basic skill required of manual braking techniques. They overreact by hammering the brakes manually causing jerking and oscillation of the aircraft as they try to maintain the centre-line.
Is this just another example of automation dependency where pilots have lost the skill and finesse of careful considered manual braking? Repeating the FCTM opening advice on autobrake use: "Use of the autobrake system is recommended whenever the runway is limited, when using higher than normal approach speeds, landing on slippery runways, or landing in a crosswind." Are pilots getting lazy or has the accent on braking automation led to pilots being apprehensive of their own ability to use manual braking? I suspect the latter...
To me that is quite straightforward. And that is there is often no need for use of autobrakes for landings other than the above examples. Common sense would assume that the mention of crosswind implies strong crosswinds and not a few knots. Similarly "when using higher than normal approach speeds" should be taken as seriously high speeds such as all flaps up or partial flap and not simply because of headwind and gust additives which are considered as normal.
It is common to observe pilots using autobrakes for practically every landing regardless of runway lengths far in excess of runway limited. Even then few pilots elect to use less than autobrake 2. Autobrake 1 is almost unheard of. In the simulator we observe pilots using autobrake 2 as a minimum on a 10,000 ft runway and if landing with one engine inoperative they up it to autobrake 3 as if there is some urgency if landing on one engine.
Some time ago, I was involved in training pilots from a large Asian operator where it was company procedure to use Autobrake 2 for every landing. Local culture being what it was, pilots stuck literally to the letter of the law. The simulator session required an all flaps up landing on a limiting runway length. If ever there was an occasion for Autobrake Max this was it. But no, the manual said autobrake 2 for all landings and that is exactly what the pilot used. The result was a significant over-run at high speed off the end of the runway. Culture has a lot to answer for.
Granted, pilots are often constrained by company autobrake policy and have little choice. But one would have thought use of autobrakes increases wear and tear and thus increased cost. McDonald Douglas published an article many years ago called "The High Cost of Hard Braking" where it detailed the cost of each landing with and without autobrakes and where it discussed the lead-footed pilots that cost the company more money by their inappropriate braking technique. It suggested that accurate final approach and touch-down speeds as well as prompt use of reverse thrust often meant that braking use could be minimised. In other words the skill of the pilot in reducing braking to a minimum. The speed at which the brakes were first applied was an important factor in the cost of braking. The higher the speed the more wear and tear. Autobrakes are applied on the instant of touch down (high speed) although they back off to maintain a specific rate of deceleration with use of reverse thrust.
There may be occasions where a turn-off at a specific taxi way is needed operationally but even then judicious combination of reverse and manual braking means braking is at a minimum. Often braking is not needed until below 80 knots where energy requirements, and thus wear and tear, are less. Again, observations in the simulator have shown that pilots addicted to autobraking for whatever reason, when asked to use manual braking, tend to get quite rusty due to lack of basic skill required of manual braking techniques. They overreact by hammering the brakes manually causing jerking and oscillation of the aircraft as they try to maintain the centre-line.
Is this just another example of automation dependency where pilots have lost the skill and finesse of careful considered manual braking? Repeating the FCTM opening advice on autobrake use: "Use of the autobrake system is recommended whenever the runway is limited, when using higher than normal approach speeds, landing on slippery runways, or landing in a crosswind." Are pilots getting lazy or has the accent on braking automation led to pilots being apprehensive of their own ability to use manual braking? I suspect the latter...
Last edited by Centaurus; 17th Sep 2014 at 03:41.
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The times they are a changing!
You would think that having an ATP rating would allow us to use common sense. Well, insurance companies and federal regulators have thought otherwise. It is funny that SOP's mandate us to use a minimum auto brake setting of 2 regardless of landing weight, runway length, or turnoff point.
But, when we have a very abnormal circumstance, which most of us have never encountered, we are allowed to use, ummmm,"our own judgement" because the performance computer can't come up with a recommended setting.
I recently flew with a very nice gentleman, fairly experienced, easy to get along with, and he punched up the recommended brake setting on the performance computer. It recommended a flaps 25, brake setting of 2 with regular reverse thrust. I said,we have a near 12,000 ft runway, a turnoff at the very end, clear calm night,perfect conditions, 100,000 lbs less than MLW, lets use no brakes, flaps 30, no reverse, and we'll be fine. The look on his face was priceless!
We are not allowed to use experience unless it is absolutely necessary, because our SOP's are lowered to the very lowest common denominator.
I'm still waiting for the FOQUA to bite me in the arse!
You would think that having an ATP rating would allow us to use common sense. Well, insurance companies and federal regulators have thought otherwise. It is funny that SOP's mandate us to use a minimum auto brake setting of 2 regardless of landing weight, runway length, or turnoff point.
But, when we have a very abnormal circumstance, which most of us have never encountered, we are allowed to use, ummmm,"our own judgement" because the performance computer can't come up with a recommended setting.
I recently flew with a very nice gentleman, fairly experienced, easy to get along with, and he punched up the recommended brake setting on the performance computer. It recommended a flaps 25, brake setting of 2 with regular reverse thrust. I said,we have a near 12,000 ft runway, a turnoff at the very end, clear calm night,perfect conditions, 100,000 lbs less than MLW, lets use no brakes, flaps 30, no reverse, and we'll be fine. The look on his face was priceless!
We are not allowed to use experience unless it is absolutely necessary, because our SOP's are lowered to the very lowest common denominator.
I'm still waiting for the FOQUA to bite me in the arse!
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Quite to the contrary,
Many major legacy carrier recommend the use of autobrakes 1/Lo and idle reverse with thrust only as necessary. Much of this is due to the advent of carbon brakes and computerized braking systems. One even smooth brake application use of both left and right brakes make much more performance and economic sense. Which the autobrake system can accomplish to a much more consistent degree than the human factor. Also AirFase will flag a late braking event, which companies frown on.
High thrust reverse landings have only a small degree of stopping power and almost nil below 100kts, not to mention fuel burn, noise and the wear and tear on your most critical and expense asset.
Now of course, I whole heartily agree; that with a long rollout in the proper conditions, skillful use of manual braking and idle thrust is the way to go.
The use of real airmenship and knowing the difference between what the manual says and what should be done for a given scenario is fast becoming a lost art of our profession.
After all is this not what we carbon based units are supposed to be doing.
Many major legacy carrier recommend the use of autobrakes 1/Lo and idle reverse with thrust only as necessary. Much of this is due to the advent of carbon brakes and computerized braking systems. One even smooth brake application use of both left and right brakes make much more performance and economic sense. Which the autobrake system can accomplish to a much more consistent degree than the human factor. Also AirFase will flag a late braking event, which companies frown on.
High thrust reverse landings have only a small degree of stopping power and almost nil below 100kts, not to mention fuel burn, noise and the wear and tear on your most critical and expense asset.
Now of course, I whole heartily agree; that with a long rollout in the proper conditions, skillful use of manual braking and idle thrust is the way to go.
The use of real airmenship and knowing the difference between what the manual says and what should be done for a given scenario is fast becoming a lost art of our profession.
After all is this not what we carbon based units are supposed to be doing.
Last edited by jimmyg; 20th Sep 2014 at 01:29.
I believe the QF group mandate auto brakes for every landing.
I remember having a conversation with a QF skipper who was horrified that I would happily land on 16 at Melbourne (3600m!) with the intention to vacate at Kilo (i.e. the far end) with no autobrake and reverse idle.
For the record the Airbus FOQA flags the event red (Braking Delayed At Landing is the code from memory). Probably why some ops departments think that it's bad.
I remember having a conversation with a QF skipper who was horrified that I would happily land on 16 at Melbourne (3600m!) with the intention to vacate at Kilo (i.e. the far end) with no autobrake and reverse idle.
For the record the Airbus FOQA flags the event red (Braking Delayed At Landing is the code from memory). Probably why some ops departments think that it's bad.
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With reference to the Boeing 737 Series. That "Bible" the 737 Flight Crew Training Manual states: Use of the autobrake system is recommended whenever the runway is limited, when using higher than normal approach speeds, landing on slippery runways, or landing in a crosswind.
With reference to the Boeing 737 Series. That "Bible" the 737 Flight Crew Training Manual states: Use of the autobrake system is recommended whenever the runway is limited, when using higher than normal approach speeds, landing on slippery runways, or landing in a crosswind.To me that is quite straightforward. And that is there is often no need for use of autobrakes for landings other than the above examples.
With reference to the Boeing 737 Series. That "Bible" the 737 Flight Crew Training Manual states: Use of the autobrake system is recommended whenever the runway is limited, when using higher than normal approach speeds, landing on slippery runways, or landing in a crosswind.To me that is quite straightforward. And that is there is often no need for use of autobrakes for landings other than the above examples.
For normal operation of the autobrake system select a deceleration setting.
Settings include:
• MAX:Usedwhenminimumstoppingdistanceisrequired.Deceleration rate is less than that produced by full manual braking
• 3:Shouldbeusedforwetorslipperyrunwaysorwhenlandingrollout distance is limited. If adequate rollout distance is available, autobrake setting 2 may be appropriate
• 1or2:These settings provide a moderate deceleration suitable for all routine operations.
Settings include:
• MAX:Usedwhenminimumstoppingdistanceisrequired.Deceleration rate is less than that produced by full manual braking
• 3:Shouldbeusedforwetorslipperyrunwaysorwhenlandingrollout distance is limited. If adequate rollout distance is available, autobrake setting 2 may be appropriate
• 1or2:These settings provide a moderate deceleration suitable for all routine operations.
Now it doesnt mean they recommend manual braking in other conditions..
Is this just another example of automation dependency where pilots have lost the skill and finesse of careful considered manual braking?
Are pilots getting lazy or has the accent on braking automation led to pilots being apprehensive of their own ability to use manual braking? I suspect the latter...
Now of course, I whole heartily agree; that with a long rollout in the proper condition skillful use of manual braking is the way to go.
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De Facto,
I see often FO's who are totally unable to do a smooth braking themselves, are unable to coordinate deceleration to match exiting a certain exit etc etc.
All because too much use of the Autobrakes, even when it is unnecessary.
Use Autobrakes when landing on wet/contaminated, limited rwy or hard crosswind.
All the other landings: Autobrakes OFF and think for yourself and be a Pilot and not an Automatics Monkey
I see often FO's who are totally unable to do a smooth braking themselves, are unable to coordinate deceleration to match exiting a certain exit etc etc.
All because too much use of the Autobrakes, even when it is unnecessary.
Use Autobrakes when landing on wet/contaminated, limited rwy or hard crosswind.
All the other landings: Autobrakes OFF and think for yourself and be a Pilot and not an Automatics Monkey
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All the other landings: Autobrakes OFF and think for yourself and be a Pilot and not an Automatics Monkey
Autobrakes OFF before landing is your prerogative,but before you jump my throat,i motivate my fos to fly raw data as much as possible and when situations allow it and if after landing they decide to use manual brakes to vacate using their deleration(ie AB chosen was too high ie landed shorter or AB was too low,landed longer than expected) then yes i have no problem and they will do it until its tiller time.
Ok for you?
I see often FO's who are totally unable to do a smooth braking themselves, are unable to coordinate deceleration to match exiting a certain exit etc etc.
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Operationally unnecessary use of autobrakes for landing
Airbus, my outfit:
Delayed Braking after Landing should only be triggered when idle reverse is not selected and/or is cancelled prematurely (i.e. Significantly above taxi speed)
In other words: an idle reverse landing with no brakes should not trigger a FOQA event.
As for the rest:
Agree with most sentiments here. Autobrake is a great tool, but manual brakes does the job a lot better in many situations. However a certain level of proficiency may be required....
Delayed Braking after Landing should only be triggered when idle reverse is not selected and/or is cancelled prematurely (i.e. Significantly above taxi speed)
In other words: an idle reverse landing with no brakes should not trigger a FOQA event.
As for the rest:
Agree with most sentiments here. Autobrake is a great tool, but manual brakes does the job a lot better in many situations. However a certain level of proficiency may be required....
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Then there are company SOPs that prefer the fuel savings of idle reverse over brake wear. Combined with another SOP - minimum runway occupancy time - you can literally end up with smoking brakes. But hey, we made the first exit!
My company (brand B) are autobrake advocates, with many Captains taking control at 60kts on the runway so many FOs get almost no chance to brake manually.
I also fly a more belts and braces type which lacks any auto brakes (or autothrottles, magenta line or VNAV) which has made me realise quite how mollycoddled one is in a modern aircraft. I use autobrake on the 737 because they pay me to, and because we spend a lot of time on short runways.
However, I flew many moons ago with a Line Trainer who had an old copy of the FCTM before the lawyers got to it, and its recommended braking technique was to progressively apply the brakes, only applying real force below 80kts as this was most effective and caused the minimum energy to be absorbed by the brakes.
I also fly a more belts and braces type which lacks any auto brakes (or autothrottles, magenta line or VNAV) which has made me realise quite how mollycoddled one is in a modern aircraft. I use autobrake on the 737 because they pay me to, and because we spend a lot of time on short runways.
However, I flew many moons ago with a Line Trainer who had an old copy of the FCTM before the lawyers got to it, and its recommended braking technique was to progressively apply the brakes, only applying real force below 80kts as this was most effective and caused the minimum energy to be absorbed by the brakes.
In other words: an idle reverse landing with no brakes should not trigger a FOQA event.
On my type the Braking Delayed at Landing FOQA event is triggered by the length of time to slow to 50kts after slowing 10kts from touchdown speed. It is invariant of Reverse selection.
And clarification to my above - it does also flag other colours, but it almost always ends up red if you have REV IDLE selected and no manual braking.
Last edited by compressor stall; 17th Sep 2014 at 10:59. Reason: grramma
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De Facto,
My mail was not an accusation towards you...I am quite sure that your abilities and technical knowledge is appreciated by those who fly with you, and those who know you on this forum.
My mail was not an accusation towards you...I am quite sure that your abilities and technical knowledge is appreciated by those who fly with you, and those who know you on this forum.
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I believe the QF group mandate auto brakes for every landing.
True. That emanated from the Qantas Boeing 747 over-run at Bangkok on 23 September 1999 where, although the autobrakes were selected, they were inadvertently deactivated during the balls up after initial touch down. After that, the company went into ACM (arse covering mode) and directed that autobrake be used on every landing where autobrake was installed on type.
You just omitted to add what is following your FCTM quote...which is:
Read the opening paragraph carefully. It states, among other things that "use of the autobrake is recommended whenever" etc etc. and gives a list of examples of when autobrake should be considered.
I read it as telling you that in the circumstances where the pilot elects to use autobrake for landing because of the operational situation of limited runway length, slippery runways and so on, then the FCTM amplifies or describes what deceleration rate can be expected with each setting. It does not imply that autobrakes are normal SOP for all landings.
Last edited by Judd; 17th Sep 2014 at 11:48.
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De Facto,
My mail was not an accusation towards you...I am quite sure that your abilities and technical knowledge is appreciated by those who fly with you, and those who know you on this forum.
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De Facto,
My mail was not an accusation towards you...I am quite sure that your abilities and technical knowledge is appreciated by those who fly with you, and those who know you on this forum.
This thread highlights many of the significant safety issues in modern operations.
Manufacturers’ recommendations being interpreted as ‘must’ (legal overtones), the limitations of SOPs, poor wording or range of interpretations, none able to foresee every situation, all reducing the need to think.
Documentary dependency, with that of automation, boxes pilots into standard operating scenarios which reduce ability to deal with the unexpected, and in some circumstances creates new operational hazards.
Many areas of the industry believe that ‘that unexpected’ will not happen – to them or in their operation; they have no knowledge of ‘it’. Alternatively, an assumption that pilots will be able managed – overreliance on human intervention in abnormal circumstances.
A problem with autobrake, as with automation in general, is that it disconnects the pilot from the feel of the aircraft. Pilots lack knowledge of applied foot-force vs deceleration, and from that, varying decelerations on runways with different braking conditions. This is accentuated with the use of reverse.
“Use of the autobrake system is recommended whenever the runway is limited …”; what is limited?
Before stating the classic certification rules, how might a pilot judge this, what information is available in the QRH, what is taught, and does this result in a consistent answer?
As a predominantly non-autobrake user (most types did not have it), why do Boeing come to their recommendation; what are the problems in the various conditions. Historically the case was made on inconsistent human performance during an RTO – a rare occurrence with less safety margin than for most operations.
Perhaps Boeing now judges that automation can better human performance in more normal instances. Yet an operational interpretation of their ‘recommendation’ often opposes the Boeing philosophy that the crew can (will) always override. The expectancy is that crews will be able judge ‘when’ to intervene, but the recommendation reduces opportunity to gain those skills required to judge, particularly in the more abnormal conditions.
Has the balance between comfort, cost, runway occupancy vs safety swung too far? On the basis of overrun statistics arguably yes, – ‘safety first’; have we really thought about it.
Autobrake = automind; think about it, what does ‘use’ mean, assume, or imply - pilots, trainers, operators, regulators, and manufactures.
Manufacturers’ recommendations being interpreted as ‘must’ (legal overtones), the limitations of SOPs, poor wording or range of interpretations, none able to foresee every situation, all reducing the need to think.
Documentary dependency, with that of automation, boxes pilots into standard operating scenarios which reduce ability to deal with the unexpected, and in some circumstances creates new operational hazards.
Many areas of the industry believe that ‘that unexpected’ will not happen – to them or in their operation; they have no knowledge of ‘it’. Alternatively, an assumption that pilots will be able managed – overreliance on human intervention in abnormal circumstances.
A problem with autobrake, as with automation in general, is that it disconnects the pilot from the feel of the aircraft. Pilots lack knowledge of applied foot-force vs deceleration, and from that, varying decelerations on runways with different braking conditions. This is accentuated with the use of reverse.
“Use of the autobrake system is recommended whenever the runway is limited …”; what is limited?
Before stating the classic certification rules, how might a pilot judge this, what information is available in the QRH, what is taught, and does this result in a consistent answer?
As a predominantly non-autobrake user (most types did not have it), why do Boeing come to their recommendation; what are the problems in the various conditions. Historically the case was made on inconsistent human performance during an RTO – a rare occurrence with less safety margin than for most operations.
Perhaps Boeing now judges that automation can better human performance in more normal instances. Yet an operational interpretation of their ‘recommendation’ often opposes the Boeing philosophy that the crew can (will) always override. The expectancy is that crews will be able judge ‘when’ to intervene, but the recommendation reduces opportunity to gain those skills required to judge, particularly in the more abnormal conditions.
Has the balance between comfort, cost, runway occupancy vs safety swung too far? On the basis of overrun statistics arguably yes, – ‘safety first’; have we really thought about it.
Autobrake = automind; think about it, what does ‘use’ mean, assume, or imply - pilots, trainers, operators, regulators, and manufactures.
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I fly the 744, not the 737, but I think the concepts are the same, except for those specifically addressing carbon brakes on the 744...
First, I believe idle reverse should be used for ALL landings. There is little reason to use the brakes to overcome residual thrust, especially at high speeds. Keep the engines in reverse until you're ready to exit the runway, or until you'd have to add thrust to continue taxiing. The next time you hit ice on the paint stripes at the end, you'll be glad you picked up the habit...
Boeing does not recommend the sue of Autobrakes 1 on the 744, because it causes the wheel brakes to cycle, which is detrimental to carbon brake life. So, if Autobrakes are used at all, it's 2 or above.
We use Autobrakes as a normal procedure. However, we also have a "hot weather" procedure which allows Autobrakes OFF on a long runway. Idle Reverse and no brakes (except for a brake check crossing 18/36C) is routine for me when landing on Rwy 09 at CVG, and other long runways where we roll out to the end.
First, I believe idle reverse should be used for ALL landings. There is little reason to use the brakes to overcome residual thrust, especially at high speeds. Keep the engines in reverse until you're ready to exit the runway, or until you'd have to add thrust to continue taxiing. The next time you hit ice on the paint stripes at the end, you'll be glad you picked up the habit...
Boeing does not recommend the sue of Autobrakes 1 on the 744, because it causes the wheel brakes to cycle, which is detrimental to carbon brake life. So, if Autobrakes are used at all, it's 2 or above.
We use Autobrakes as a normal procedure. However, we also have a "hot weather" procedure which allows Autobrakes OFF on a long runway. Idle Reverse and no brakes (except for a brake check crossing 18/36C) is routine for me when landing on Rwy 09 at CVG, and other long runways where we roll out to the end.
My company has no restrictions on the level of autobrake (0 --> max), only that a minimum of idle reverse is SOP on all landings. We also have to check the landing performance, not such a bad idea really? Then use auto brake (or not) and reverse to suit.
On the 777, AB1 with Reverse (full) can lead to increased carbon brake wear as the deceleration rates are not that different, so leading to the brakes coming on and off repeatedly.
alf, I agree with pretty much all you have said. As a Boeing pilot at the moment, we are just in the process of being provided with new QRH data which will have different factors applied. I’m not sure quite what this will look like but I think it might mean the end of test pilot stopping distances with corrections to apply, replaced with something more akin to real life. I’m awaiting with interest.
On the 777, AB1 with Reverse (full) can lead to increased carbon brake wear as the deceleration rates are not that different, so leading to the brakes coming on and off repeatedly.
alf, I agree with pretty much all you have said. As a Boeing pilot at the moment, we are just in the process of being provided with new QRH data which will have different factors applied. I’m not sure quite what this will look like but I think it might mean the end of test pilot stopping distances with corrections to apply, replaced with something more akin to real life. I’m awaiting with interest.
I’m intrigued by the "hot weather" procedure.
For given landing the amount of energy to be dissipated is constant. This should total Brakes + Aerodynamic + Reverse. The contributions of autobrake or manual brake without reverse should be identical – irrespective of braking level; with reverse, autobrake might better optimise the contribution of reverse, thus would absorb less energy. This should give a cooler brake than manual brake if used at a similar stage of landing, but probably not greatly different if manual is used later as the effect of reverse diminishes.
Thus why would manual braking result in a cooler brake?
For given landing the amount of energy to be dissipated is constant. This should total Brakes + Aerodynamic + Reverse. The contributions of autobrake or manual brake without reverse should be identical – irrespective of braking level; with reverse, autobrake might better optimise the contribution of reverse, thus would absorb less energy. This should give a cooler brake than manual brake if used at a similar stage of landing, but probably not greatly different if manual is used later as the effect of reverse diminishes.
Thus why would manual braking result in a cooler brake?
I’m intrigued by the "hot weather" procedure.