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Changing auto brake setting during roll out
I’ve not seen any specific guidance against this or done it personally If I’m not getting the required deceleration i’ll disconnect the AB and manually brake But I’ve seen it done and curious as to thoughts on this technique |
Madness...
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Technically possible but what's the point? It's a gimmick and lacks class
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It seems like a good/acceptable idea until you accidentally hit MAX
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I often changed the auto brake settings on the B757. It was a smooth operation. I never used the technique to increase braking.
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Originally Posted by InSoMnIaC
(Post 10288971)
It seems like a good/acceptable idea until you accidentally hit MAX
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Seen it being done, never really understood the point, especially when people would change it mutiple times during rollout (i.e. 3 to 2, then 2 to 1). Isn’t it much easier just to press the pedals to disconnect the autobrake and brake manually? |
If you are not getting the required deceleration changing the setting might not work if the reason is a fault with the system. Once you work that out you have even less time for the manual option. |
I often changed the auto brake settings on the B757. It was a smooth operation. I never used the technique to increase braking. It's in the 737 FCOM that autobrakes can be selected and changed during landing roll out. No warning or caution. |
It seems like a good/acceptable idea until you accidentally hit MAX Exactly my thought too. I don’t use the above technique and prefer to select a slightly lower setting than required and override to disengage. |
Originally Posted by InSoMnIaC
(Post 10288971)
It seems like a good/acceptable idea until you accidentally hit MAX
CP |
Not all aircraft use knobs to set autobrake. |
Ummmmmm..........:8 |
Originally Posted by AmarokGTI
(Post 10289071)
If you are not getting the required deceleration changing the setting might not work if the reason is a fault with the system. Once you work that out you have even less time for the manual option. Say you've prepared performance rollout data for a WET runway but during landing its damp at best if anything. Having checked DRY and WET performance prior to landing, you know that a lower AB setting would make the desired exit in DRY conditions. Lowering the AB eating to the desired lower one is good airmanship in this case, alternatively, manual braking to disconnect the higher auto brake selected the other option. |
Skyjob: AB usually provides a controlled deceleration rate.
The Boeing RTO OFF-1-2-3-MAX is far superior to AB's LO-MED MAX in the interface, given the task suggested above. AB: no, unless you really want to do the inevitable. B: to reduce decel rate? Worked nicely, I seem to remember (steel brakes at the time). |
Routinely in normal conditions doesn't make any sense. But in rain and crosswind etc. if one wants to increase braking effect not a bad idea to change to medium from low. You are assured of even braking.
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It’s the poor man’s Brake To Vacate...!
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Lowering the AB eating to the desired lower one is good airmanship in this case, alternatively, manual braking to disconnect the higher auto brake selected the other option. |
Not necessarily against it, particularly in adverse conditions with gusty winds and a wet / short runway But If you do, I think it should be the PNF that adjusts the setting, it’s an awkward reach to where the selector is usually located and an unnecessary distraction to the PF I was in the jump seat of a 747 Classic a few years ago however that had the AB selector mounted on the left side of the overhead panel in easy reach of the CA |
Changing Auto Brake Selection after touchdown.
Originally Posted by InSoMnIaC
(Post 10289281)
Not all aircraft use knobs to set autobrake. |
How about moving the flaps up at the same time? |
Originally Posted by CaptainProp
(Post 10289274)
Exactly THAT! What a load of BS! Taking your eyes of the runway on rollout to “locate” switches and stuff is simply unprofessional. As far as I’m concerned you touch nothing until clear of runway and spoilers are being disarmed. CP What I am aluding to is that no proper professional pilot will take their eyes off the situation outside unless the aircraft is fully under control and the conditions are benign. When it is fully under control, looking down (or up) for a second to change a switch.......is it such a big risk? If it is, just ask the other pilot for what you want. Hard hat on to deflect incoming................... |
This happens all the time in my airline, the 75/76 auto brakes are very smooth so modifying the decel rate is almost standard practice. Regarding taking your eyes off the runway well no probs as the auto brake selector is in PM’s area of responsibility. I love the ‘madness’ shouts, they make me laugh and just show cultural differences between airlines. |
I was a passenger in a FR 738 some time back when the crew inadvertently selected what I believe to be RTO during the landing roll out. The sudden decelaration was enough to propel me into the seatback in front, I sustained a minor injury to my right hand while trying to save myself. Very unpleasant and no explanation from the flightdeck. Senior Cabin Crew was in the flightdeck during disembarkation asking WTF was going on.. |
I don't do it - unpleasant jolt on the 787 if you go twiddling the autobrake knob, which isn't conveniently located to begin with. Especially when you have the deceleration scale in the HUD, why would you want to? Do the performance calculation properly, land it in the right place, and leave the autobrake in until taxi speed.
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I just heard a theory that the PNG crew increased their autobrake setting at 50’ in heavy rain at Truk. It seemed like a good idea at the time. |
Why are aircraft fitted with autobrake ? Why do pilots use autobrake ? Why change settings ? After any serious incident, the press release will always state that “safety is our first priority”. |
Just read your damn bulletins |
Never a problem on 75/76 in my experience. |
B757 FCOM Systems: ”Autobrake application occurs slightly after main gear touchdown. Deceleration is limited until the pitch angle is less than one degree, then deceleration increases to the selected level. The deceleration level can be changed (without disarming the system) by rotating the selector.” |
I don't mean to step on toes, and I understand autobrakes are a tool to be used and probably nice to have, especially the bigger and heavier the type gets. But I agree with the notion of why go through the trouble of fiddling with selector knobs or buttons when there's two big pedals at your feet you can use? It might not be as accurate as the computers can do it, but I think I managed about 10 years of flying so far without giving the passengers any injuries or bruises from their seatbelts (my type does not have autobrakes).
Taken to extremes, next up we will have accidents because pilots don't know how to brake with care anymore ;). |
Wait a minute, you have your feet on the rudder pedals and you’re fiddling with a switch down FO’s knee to modulate the braking?!? We’re doomed.
The car radio analogy? Anyone think fiddling with a speed control setting on the dash screen is a great idea when you have your foot of the accelerator?? Can you do it? Sure. Great idea? Debatable. |
‘It’ (radio or AB) can be changed; should it be, is it necessary. Is there less distracting alternative - aircraft, yes, manual braking. Re bulletins: Who writes / authorises the bulletins ? What do they say, why, to what purpose ? Who holds the final safety responsibility for the bulletin ? … for the aircraft … You ? |
I've seen somebody disengage the AB via the pushbutton on the panel (A320) during rollout. What if he'd selected max instead? Would anyone die? Probably not, but there's some risk of injury with max AB, I assume.
There's nothing expressly prohibiting it, but it just seems like way more work than using the pedals. Not worth me getting worked up over it though. |
We are to disconnect autobrakes via manual braking, not using the switch. I believe that is still required across all fleets at our company. I can understand directing the PM to change the auto brake setting during the approach because of unanticipated conditions. I can not understand doing that on the runway. So the Captain is landing and now decides to: take his eyes off the runway, look over to the autobrake panel, take his right hand off the TL’s and reach across the cockpit to deselect, select, or increase the AB setting. Or one may say, well no, he directs his FO to do the action. So now that FO is presented with a command from the Captain he most likely has never encountered nor anticipated and is to complete during a critical phase. I can easily imagine a hundred things which could go wrong. Isn’t our job to manage the threats inherent in our occupation not add to them? |
Doobler China
It was either " Madness" or " Moronic", so I say figured the former was less insulting.
On a technical level , there is no advantages ( on the 737, anyway) and only a heap of hurt if getting it wrong. The fact that a bunch of test pilots with zero line experience has gotten away with using it , and does not see the potential for a disaster in our hands , repeating it a few million times a year , instead of proper conservative breaking , means nothing. In my book! Another little thing on the 737 the autobrake some times does not arm. All you do then is go to zero for a few seconds, then back to desired selection , and voila, it arms. Doing that midfield at 100kts eats rwy!? Anyway I recall doing a thing or two some times back, when the "culture" was somewhat more relaxed. Sure we had fun , and we were good, but most of the time lucky. Buzzing my Brothers farm on empty trips at 100 feet comes to mind,,, You all have fun now Cpt B |
I disagree but can’t be bothered arguing, different types, different airline cultures. All the best. |
On a technical level , there is no advantages ( on the 737, anyway) and only a heap of hurt if getting it wrong. |
Nowhere in the 737CL FCTM does it imply fiddling about with the autobrakes after landing, this action surely is a "kludge" at best!
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Nowhere in the 737CL FCTM does it imply fiddling about with the autobrakes after landing, this action surely is a "kludge" at best! |
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