Inadvertent touching of brakes in 737 during takeoffroll

[Centaurus]

Thought this might be useful information for simulator instructors and in real life.

Event: Teaching new students(250 hours each) the step by step sequence of actions for a rejected take off roll. The simulator was set so that if all actions performed correctly the aircraft would stop with 100 metres to spare. Abort speed was 100 knots with instructor calling "STOP" at 100 knots and then standard abort actions taken by PF. The instructor IOS has a pop-up picture that activates as soon as brakes applied, whether autobrake RTO or manual braking. You can see if brakes applied equally as in RT0 or unevenly if manual braking (often happens). The latter invariably extends the abort distance.

First student consistently did well and stopped with approx 50 metres to spare. Second student actions were fast and correct yet he consistently over-ran the end of the simulator runway and causing much scratching of instructor's head to determine why the over-runs,when the student seemed to be acting correctly. During another takeoff run by this student, the instructor just happened to glance at his own instructor screen and was astonished to see the brake pop-up picture appeared and indicated rapid variation of braking taking place at very low values but nevertheless it was obvious, although nothing felt through the simulator. The indications being the student was inadvertently applying some braking during the take off roll. This explained the over-run as the takeoff roll was being extended due to brake drag.

The student vehemently denied touching the brakes during the takeoff roll. OK, that was put down by the instructor to a possible ethnic loss of face culture thing. A recorded picture of the instructor screen was used to demonstrate that brakes were indeed being activated; albeit spasmodically. . The point of mentioning this event in Tech Log is to point out to line trainers that unless the aircraft jerks slightly during the takeoff roll signifying possible inadvertent touching of the brakes, it may be impossible to know if slight inadvertent brake operation is happening which may invalidate V1 and worse still cause heat build up in the brakes and tyres. All the more reason to emphasis to new pilots on type, the importance of proper toe positioning on the rudder pedals for take off i.e. at the bottom of the pedals

[pineteam]

Feet at the bottom or up on the pedals is another big debate amongs Airbus pilots. in our SOPM, feet must stay at the bottom as we had an incident where a fo applied braking during take off. But lots of pilots including some instructors don’t follow that rule. Apparently according to an Airbus meeting they recommend feet up. That’s what an instructor told me. I have no documentation about it. But I also read in one of our old safety magazine Airbus recommended feet at the bottom lol.
In the CBT, it shows feet up on the pedals tho.:}I keep my feet up also as I like keeping the same position for take off and landing. I used to keep them at the bottom for the reasons you mention. I guess unless it’s written black and white, it should be at pilot choice.

[RAT 5]

Before RTO systems was always taught heels on the floor. Again, being only a Boeing guy, I'm curious why pilots put things like this into type category. Airbus recommend this, Boeing that, Embraear something else. Remember the crash In Russia with the ice hockey team on board. One contributory factor was the inexperienced on type RHS pilot had some brake applied during most of the takeoff.

[pineteam]

I think it depends how the rudder pedals are designed. If someone is braking during the take off roll, then something is wrong with him or improper training. On Airbus, you need to apply decent pressure before it will start to actually brake. It happened before tho.:}

Anyway, I keep my feet up and feel comfortable about it. In case of sudden loss of power on one engine, you would have better control with the feet up. That's one of the advantages. I'm definitely not criticizing people having their feet down on Airbus, I used to do the same and it's totally doable. But I believe Airbus has designed the rudder pedals for the pilots to have their feet up. At least, that's what the official CBT from Airbus is saying::p

https://ibb.co/eJm6MT

[eckhard]

The Airbus pedals have a built-in rest for the heels, when they are up. Also, the rubber covering makes it more difficult to slide the feet up. For these reasons, I prefer to be feet up in the ‘bus.

On the Boeing, there is no heel-rest and the pedals are shiny, which makes it easier to slide the feet up. For these reasons, I prefer heels on the floor in a Boeing.

I too have experienced a student inadvertently applying brake pressure during take-off. Difficult to prove, as it was in the aircraft (Citation) and therefore no read-out but I could feel some snatching during the roll and a definite lurch into the air when the wheels left the ground.....

[Derfred]

In a crosswind, I find it quite difficult to transition from autobraking to manual braking with heels on the floor. How do you slide your feet up with constant pressure on a rudder pedal? I can’t. If I try I always lose rudder pedal pressure, and therefore a swing off the centreline.

This goes for both the RTO case as well as normal landing case. So for both takeoff and landing, I don’t like heels on the floor. However, I would like to think I would never go near to touching the brakes inadvertently.

Maybe I need to buy shoes with a more slippery sole. But then I would slip on the stairs or an oily tarmac.

[RAT 5]

Thanks Eckhard: Good information.

[Judd]

Before RTO systems was always taught heels on the floor
There are probably thousands of unreported occasions where a pilot had inadvertently touched the top of the brake pedals during the take off roll. Sometimes more prevalent with someone with big feet or having his seat too far forward and thus cramping leg movement. Or maybe deliberately choosing to have his toes resting on top of the rudder pedals "just in case" he needs to instantaneously stop during the take off run. In a similar vein, there are pilots who when their hand is on the thrust levers during a take off roll, deliberately bend their hand like a bird's claw over the top of the throttles as if to signify he is poised and ready to rip the throttles back in an instant should something untoward happen. I found that having one's feet high up on the pedals during take off roll or landing means my ankle is at an uncomfortable angle and feels unnatural.

Keep in mind it takes a fraction of a second to move one's toes when required, from their comfortable position at the base of the rudder pedal, to the max braking position at the top of the pedal. During elementary flying training in Cessna singles most pilots were taught to taxi, take off and land, with feet at the bottom of the pedals. Reason why? To avoid inadvertent dragging of the brakes. Why any different with airline aircraft?. .
Early aircraft with rudder bars and no toe brakes usually have mechanical brake levers and use differential directional braking by pushing one rudder pedal and gently squeezing or pulling back on the brake lever. Yet I have never seen a pilot on these types (Chipmunk for example) taking off with one hand wrapped around the brake lever ready for instant action if an abort happens.
The early Boeing 737-100/200 FCTM displayed a diagram showing the takeoff and landing technique of having the feet high up on the pedal but with toes bent back just clear of the top of the rudder pedal. It was damnably uncomfortable but showed how instant brakes could be applied if needed. Later issues of the FCTM had this diagram removed. Maybe for a good reason based upon how easy it was to inadvertently apply brake pressure without being aware of it?

[LW20]

Airbus pedals have a complete different design than the B737 pedals. Contrary to 737 pedals, Airbus Pedals do not allow to quickly slide your feet up into a position where max braking is possible. This is due a much shallower angle, the rubber coating and the length of the pedals so that the whole feet can rest on it.

[Derfred]

Keep in mind it takes a fraction of a second to move one's toes when required, from their comfortable position at the base of the rudder pedal, to the max braking position at the top of the pedal

Really? In nil wind in a simulator?

Frankly, I disagree. Especially in a crosswind,

[Asiri37]

On landing you need to apply quite some pressure before the autobrakes disengage, I would assume its the same with RTO. I agree with the point that it is better to have the feet up, transtion and sliding the feet up might not be possible at many sitautions, with the losing some kind of directional control.

[busav8r]

As for the feet position on the rudder pedals during takeoff and landing, the Airbus recommendation is to have feet up on the pedals. That doesn't apply on the Boeing and all other westerly made commercial aircraft that I know, where feet must always be on the bottom. And that is only related with the rudder/brake pedals design and the way they operate, which are completely different. This can be easily demonstrated on the simulator and must be introduced and taught to new (and old) pilots during their TR courses.

https://www.airbus-win.com/wp-content/uploads/2018/05/preventing-runway-lateral-excursions-the-crosswind-landing-technique.mp4
(Even though it's an interesting video, you can go directly to minute 13:40)

https://drive.google.com/file/d/1Nzx7K8wwyvnf45kKKFQvvWB8F6DFKUKg/view

[misd-agin]

"Feet must always be on the bottom" for non Airbus aircraft is an opinion. Fly the Shorts 330 in a cross wind and you might develop the technique of keeping your feet 'up' for takeoff and landing. Twenty six years of no problems with my feet 'up'.

[pineteam]

As for the feet position on the rudder pedals during takeoff and landing, the Airbus recommendation is to have feet up on the pedals. That doesn't apply on the Boeing and all other westerly made commercial aircraft that I know, where feet must always be on the bottom. And that is only related with the rudder/brake pedals design and the way they operate, which are completely different. This can be easily demonstrated on the simulator and must be introduced and taught to new (and old) pilots during their TR courses.

https://www.airbus-win.com/wp-content/uploads/2018/05/preventing-runway-lateral-excursions-the-crosswind-landing-technique.mp4
(Even though it's an interesting video, you can go directly to minute 13:40)

https://drive.google.com/file/d/1Nzx7K8wwyvnf45kKKFQvvWB8F6DFKUKg/view

That's a nice document! Thank you! I think it's safe to say now Busav8r ended that endless argument. It is indeed acceptable to have heels down by Airbus but it's NOT the best practise and not what is recommended in any of the Airbus official document.
The war is over. Feet UP won! xD