Latest AAIB Report 12/2011 - Inadvertent brake application by PF on take off roll.
 

http://www.aaib.gov.uk/cms_resources...DM%2012-11.pdf



Interesting incident just published caused by captain inadvertently applying brakes during take off roll. Aircraft did not respond to elevator at VR and copilot took it upon himself to close throttles and initiate rejected take off.

The brake pressure being applied unknowingly by the captain caused the nose wheel to be firmly attached to the runway until at VR when the nose down moment was so strong that up full elevator was unable to raise the nose more than a couple of degrees. The copilot thought the aircraft was un-flyable and whipped the thrust levers closed.

In the 737 simulator some years ago, we were practicing rejected take off procedures with two 200 hour cadets from Indonesia. Although both cadets performed each rejected take off correctly, one cadet frequently over-ran the runway.

During one take off run, it was noticed by the simulator instructor watching a selected page on the instructor screen that intermittent partial brake pressure was being applied (between 100 and 250 PSI) during the roll conducted by that cadet. This suggested he probably had his toes on the brakes without being aware of it. In turn, this extended the take off roll and invalidated the performance. Due to cultural mores he refused to believe it was his fault and denied inadvertently applying slight brakes.

When his crash mate was placed in the instructor seat and told to report what he saw on the brakes pressure display, only then was the cadet convinced he was at fault. No problems after that.

The AAIB report above is most instructive because it quantifies brake pedal angle with brake pressure applied. This revealed that the elevator was ineffective in raising the nose because of the down pressure on the nosewheel caused by partial braking.

Presumably this could happen on any aircraft depending on geometry and other factors. Indeed, like the subject aircraft in the AAIB incident report, this could persuade a pilot to abort after VR if he thought the aircraft was unflyable.

Of course, its a bit late to say to the PF "get your size 10's off the bloody brakes" if the aircraft was not responding to elevator control at VR. But an interesting discussion nonetheless if only because because there have been accidents due to the PF riding brakes inadvertently during take off.

I had some difficulty with that link so try this one.

Air Accidents Investigation: Download PDF document

Obviously not the best practice :
That one makes more sense :

Yes! And I'm a big BACK TO BASICS kind of pilot.

**Heels on the FLOOR for every takeoff please**

This should be taught at the beginning of every pilots career.

The fundamental problem with the type involved, and several others, is the angle at which the pedal resides, which makes inadvertent brake application much more likely than it should be.

Of course, the footwell is an area where space is often at a premium, but there should be no excuse for a pedal design which makes it difficult to have the feet positioned on the pedals to permit accurate brake application only when it is conscious.

The absence of a relevant certification standard, lack of dialogue between designers and ergonomics experts, lack of awareness of the problem (probably by everyone), and a ready acceptance of shoddy work in this specific aspect of design by too many folk involved in test and development, have all played their parts.

This idea that heels should rest on the floor only holds water if you assume that you will never reject at speed in a crosswind or with an engine failure, or that the autobrake (if fitted) is utterly reliable.

Otherwise, the motion required to reposition the foot (feet) on the pedal(s) necessarily involves reducing rudder force to zero, even if only momentarily. This destabilises the trajectory and causes big problems.

A combination of properly-designed pedals and some sort of acceleration monitoring (called for over many years but only now looking like a reality on some very modern types) is the answer, not a dictat to pilots that they should risk their aircraft by using a technique which deprives them of immediate access to their brakes.

Do you have reports or anecdotes in mind which would support the mention of big problems ?

How about if you "reject at speed in a crosswind or with an engine failure"?

My best evidence, personally observed, is from seeing 'heels on the floor' pilots reject in the sim, especially with strong crosswind or a nasty swing such as from N1 seizure at a moderate speed on aircraft with wing-mounted engines.

This latter case can be particularly exciting if executed below the min speed for autobrake engagement... As one pilot put it in the debrief, "I realised I could keep straight but not stop, or had to decide to lose directional control to get to the brakes..."

If stopping suddenly is a possible operational requirement, it's up to the designers et al to provide an environment which allows the pilots to do that. In fact, some discussion here is of work-arounds to cheat the poor design, and that's bad news wherever you find it.

That some manufacturers put non-slip material or features on the pedals shows me that they don't believe sliding feet on them deliberately is part of the pilot's task either...

Yes, different strokes for..., my feet are off the floor for takeoff and landing, works good, lasts a long time (AB). :ok:

It is a fact there is a transition to take place, I agree.

Now, what's behind the words to lose directional control or big problems ?
Is it a very temporary and limited variation of the heading or is it enough to put a wheel off ?

Are we aware of reports recommending to keep the heels clear of the floor ?
The present report does not recommend either to keep the heels on the floor, but it could easily have done so ...

On my side, the heels have always been on the floor as long as braking was not applied, works good as well.

This incident should be proof enough of the inadvisability of the 'heels on the rudder pedals' steering technique.


It is simply too easy to apply the brakes inadvertently.



When you need to use the brakes move your feet up to use them, yes this may be a difficult transition sometimes in heavy crosswinds but it's one we all have to do and with care it's not a problem.

For me it depends. In an Airbus with the giant pedals it is feet all the way up for takeoff and landing. In a Boeing it is heels on the floor until brakes needed. About equal time in each and never any problems with x winds, engine faliures, or rejects.

During a reject after a sudden cut at/close to V1 with a big boot of rudder to keep straight, I would find it very hard to slide my feet up the pedals to apply maximum braking. I would venture to suggest that it is almost impossible to "slide one's feet up" the pedals whilst applying any reasonable steering force; I would have to virtually pull my feet completely off the pedals first. Obviously, rather undesirable on a balanced-field reject. As far as I am concerned, wherever your feet are at the failure is where they are going to stay for the reject.

On all takeoffs my feet are right up ready. These incidents do however reinforce the need to keep one's toes off the brakes, wherever you have your feet.

Hi Capn Bloggs,

Surely it depends on the features installed on the aircraft? Most modern manufacturers have bothered to fit autobrakes. Why not use that feature and avoid running the risk of applying the brakes unintentionally during the 99.99% of your successful take offs?

Have you never come across a low experience pilot, who didn't have their heels on the floor, and who applied the brakes unintentionally during the rudder control check during taxy?

If the RTO is performed below the autobrake threshold speed, then there is plenty of runway ahead and time to sort out your feet transition from floor to brakes.

I subscribe to heels on the rudder bars and toes held clear of the brakes, until needed.

A recent landing performed by Bloggs (not Capt Bloggs) saw full left rudder and close to 200 degrees brake temp on the right bogie. IMHO Bloggs couldn't apply symmetrical braking because the left leg was fully extended and not able to provide much braking, whilst the right foot did most of the braking.

An illuminating lesson for both of us.

I thought a recent Boeing document recommended pilots should be Go-minded rather than REJECT minded - due to the propensity of pilots to abort unnecessarily. The general rule in the 737 FCTM was to use 80 knots as a trigger to stopping for any master caution. In that case why have your feet "ready" on the brakes when there is no problem with pulling up.

Above 80 knots the advice is to keep on going depending on the problem and in any case that is why the RTO is installed on most modern jet transports. It is the instinctive reaction at high speed where an unnecessary abort becomes dangerous if the statistics are to be believed. Keep your toes on the bottom of the rudder pedals and your heels on the floor has served the test of time:ok:

Progress
 

Clarrie,

I guess they don't teach them to adjust the pedals to allow full brake with full rudder anymore...probably interferes with their social life! :ugh: :ugh:

Stay Alive,

I have heels off the floor for every takeoff. Here is a classic example of why...

The brakes are operated by applying pressure to the top of the rudder pedals. The brakes can be operated from either the left or the right pilot seat through the dual rudder pedal system.

Examination of the rudder pedals by TSB investigators determined that, with the feet placed with the heels on the floor, very little pressure could be applied to the tops of the pedals to operate the brakes. It was possible to position the feet higher on the pedals so that the rudders could be operated without exerting pressure on the brakes, while also permitting the brakes to
be operated simultaneously with deflection of the rudder pedals.

The pressure exerted by the FO’s foot against the right rudder pedal prevented repositioning the foot higher on the pedal to operate the brake. The FO was unable to operate the brake for directional control because he was unable to release the pressure on the rudder pedal without losing the directional control provided by the rudder.


Findings as to Causes and Contributing Factors

1. The aircraft was operating in environmental conditions conducive to snow
penetration into the brake assemblies during ground operations at Kenora.
2. The brake assemblies on the left main landing gear froze, preventing the wheels from
rotating during the landing roll at Dryden.
3. The first officer’s foot position and pressure application on the rudder pedals prevented effective use of differential braking and nosewheel steering to maintain directional control of the aircraft after landing.

Findings as to Risk

1. Although the practice of pilots placing their feet on the rudder pedals with their heels on the floor reduces the risk of tire damage from an unintentional brake application, the practice creates a risk that pilots will not be able to use the brakes to maintain directional control.



http://tsb.gc.ca/eng/rapports-report...6/a04c0016.pdf

Thanks a lot for the link punkalouver.
Interesting.
Once again excellent report by the Canadians.

Now, we have 2 reports that contradict themselves, and for good reasons.

No wonder my SOP and FCTM don't address the subject ... blamed if you do and blamed if you don't.

I would be interested to see if there are any operators that teach this 'heels on the rudder pedals' technique.


I know it's not a Boeing procedure and I think it's disadvantages far outweigh any gains.

We don't have AB on most of our jets.

Nope. FOs don't do the rudder checks here! :}

Agree. But the issue is a V1 cut/fire.

Punkalouver's post further makes my point about moving feet up during a max-brake reject. Practically, it can't be done. :ouch:

The general rule is that if you have a fire or a large loud bang before V1 you stop. That means max braking. The issue is not what happens 80kts (or even up to V1-10), surely that's obvious?

Possibly correct but equally possibly Bloggs had the seat adjusted so that s/he could apply brake & rudder statically but once full rudder was applied dynamically, with gusto, and the leg tensed there was no ability to slide the foot up the pedal to apply brakes.

It's a bit chicken and egg. Did the rudder input lead to the asymmetric braking to maintain directional control, which was a bit wobbly, or did some initial asymmetric braking lead to full rudder for directional control thus subsequently preventing the application of symmetrical braking?

I don't see the issue here. First item is to close all thrust levers ... asymmetry no more.

Punkalouver's post is about a frozen brake at touchdown.

Very foolish to keep heels on the floor. That is why this Dash-8 went off the runway.

From captain's report...

Usually I perform rudder operation during landing with my heels in contact with the cockpit floor. As I had to use full rudder to maintain the direction in case of this incident, I performed simultaneous rudder and brake operations without a chance to change my foot position on the brake pedal. As a result, I think braking effect was not sufficient.


From safety board analysis...

It is estimated that the PIC could not apply force on the brake pedal with sufficient force when he noticed the inoperative steering because it was his habit to control the pedals with his heels on the floor up to shortly after touch down. The movement of the brake pedals was not sufficient due to the positioning of his feet.

http://www.mlit.go.jp/jtsb/eng-air_report/JA841A.pdf

Feet resting on brakes for takeoff ? 'kin dangerous :eek:

Landing actually.

My 1976 edition of the Boeing 737-200 FCTM which was much more detailed with explanatory notes than the current dumbed down FTCM Boeing 737 series, displayed a diagram showing where the heels should be for take off and landing.

In both cases the heels were on the bottom of the rudder pedal and the toes were obviously higher up but just clear of the top of the brake pedal. In practice this was a most uncomfortable feet angle and most of the crews I worked with on the 737-200 in those days disregarded that FCTM advice. Mind you the -200 did not have the RTO facility.

Later editions of the FCTM had that diagram removed. In my experience there is a demonstrable danger of inadvertent rudder pedal pressure being applied if the heels are not on the floor as experienced in the first post. Accident records appear to show that there is more risk involved in a high speed rejected take off than with a continued take off. In any case, with the RTO facility up there with weather radar as one of the most significant advances in flight safety in recent years, there are now less risks involved in rejected take off's than in the old days.

Nevertheless it is usually better in the long run, to be go-minded. Yet I still see pilots in the simulator that during the take off run have their hand wrapped around the thrust levers like a claw poised to rip the thrust levers back right up to V1. This is a learned gimmick and looks rather quaint as well as useless, considering it only takes a fraction of a second to close the thrust levers using normal hand grip

Talk about over-engineering things...

Heels on the rudder, toes on the brakes; need to brake pronto? Don't waste a little extra time you can gain by attempting to move your toes to the brake pedals. Be as ready as you can be for any outcome.

Don't need to brake? Don't step on the bloody brakes! It's really not that hard :ugh: :ugh:

Not once I've been told to remove my heels off the pedals and not once I have had any type of scare because of that. But I've been mighty glad, though, that I have been able to brake just at the moment I wanted to and not wasted time and effort trying to move/slide/whatever my feet to the brake pedals.

Don't over-complicate really simple issues. Please :suspect:

Thanks for that last report punkalouver.
I can see now there are 2 schools for that matter, I would not have thought so. As sheppey wrote, the FCTMs do not seem to specify anything on that subject. My way to do it is heels on the floor, toes clear of the brakes as long as braking is not necessary. That's the way I've been teached and I'm very comfortable that way. It provides me a more accurate control, like the need to use the armrest to get a more precise control on the sidestick.
But actually I don't know how are doing the guys I'm working with, so I will take a few months to observe and question, and I'll be back here to report ...

Page 7, near bottom of page for another runway excursion(SF340).

http://www.mlit.go.jp/jtsb/eng-air_report/JA001C.pdf

"I pressed the left brake pedal more firmly to stop the Aircraft from veering, but this attempt had no effect and the Aircraft continued veering and went off the runway. I don’t use the brake pedals while controlling the rudder, because doing so is rather difficult."

A320 Sim session,wet runway and crosswind of 20 kts,Up wind engine failure at low speed.To maintain on the runway, along with full tiller and full rudder, differential braking was required. Found it much easier to handle the situation if the feet were on the rudder pedal,rather then raising them from the floor.

As is being discussed here we also have two school of techniques since the FCTM and FCOM are silent on this. Therefore, wouldn't it better to start T/O roll with feet on the rudder pedal and slide them down at about 75- 80 kts as rudders become effective.Suggestions please!!
Thanks in advance.

Hi 320p,
You'll need most rudder deflection at low speed during the take off roll and will therefore have a bigger chance of applying unintentional braking.
Using the same logic, why don't you drive with your left foot covering the brake pedal on your car whilst driving on the motorway?

It's the delay in recognising the engine failure, before the TLs are closed which causes the problem. In real life, the change in heading will be felt early, whereas the sim points in the same direction (no clue there). You'll also feel the sideways acceleration immediately, the sim has to roll in order to simulate the yaw and consequently lags.

Eh? The SIM yaws dramatically into the dead engine (twists horizontally). Roll is not required, nor is it used by the SIM mechanism to simulate an engine failure on TO.

I've never had an issue inadvertently putting on the brakes when using lots of rudder. In fact, as stated before, trying to move one's feet up from the floor whilst putting in near-to full rudder is all-nigh impossible unless you've got very shiny soles and very shiny rudder pedals.

No question in my mind; feet up all the time; just don't toe the brakes inadvertently. Heels push the rudder, toes put on the brakes. If you have to stretch so much that you can't stop your toes moving forward and applying the brakes, you're sitting too far back.

Through how many degrees can it twist horizontally?
Once it is at the limits of motion, the sensation is that you've arrested the heading change even though the picture may show you are still turning.
How do you simulate a prolonged sideways acceleration?

Edit:
It may be a different story when we get these.
Simulators get real - Learmount

the sim banks to one side and the display as well the instruments tell you that you are turning and not banking.

its pretty the same like it pitches up on take off roll ( without showing you the pitch on instruments or visually) and you get gravity force as a feeling for dynamic accleration.

i remember being first time in a bae146 simulator and was amazed that it gives you accleration during the whole take off run and asked myself how it can be possible until one technician explained me how its done.

cheers

Rudderrat, when at the SIM next, stay outside and watch one in action. Being a pilot, you'll quickly pick up what's going on inside without even seeing the instruments.

Heading change during takeoff? You'll get about 20° (quick twist by the SIM) and then you're in the grass anyway. You won't be doing a 180° on the SIM jacks.

Hi Capn Bloggs,

Have a look at Page 9 http://www.simdesign.nl/pubs/integra...ing_system.pdf.
"For example, a pitch up attitude of 20 degrees (common for the simulation of a take off) will reduce the available motions in all other directions and rotations to nearly zero,"

During a RTO, the pitch down of the box to simulate the retardation can be about 20 degs. That reduces the available rotations, causing the loss of vestibular feed back.

Suffice to say, after 15 years in two different SIM types, I've never had a problem working out what the aircraft is "doing" during a reject or anything else, for that matter. Have you?

Lets get back on thread, shall we?

Hi Capn Bloggs,
You must be a genius, because most crews find keeping the "aircraft" (the sim) straight during a normal landing more difficult than real life. Once a heading oscillation starts, it is very difficult to damp out during braking because of the lack of sim fidelity caused by the lack of motion cues (reasons given above).

During an RTO, you will probably build a heading oscillation in an attempt to keep it within the width of the runway. If keeping your feet on the brake pedals during all normal take offs works for you - then carry on.

I'm simply trying to point out that "fixing" a sim fidelity RTO problem by keeping your feet on the brake pedals during the acceleration phase, might not be the best solution for all normal crews in normal everyday operations. See post #1.

For those who are arguing in favor of having heels on pedals: the was a fatal crash exactly for this reason. September 2011 Yak-42 in Russia ( 2011 Lokomotiv Yaroslavl air disaster - Wikipedia, the free encyclopedia ). Pilot previously flew on Yak-40, which had pedals designed in such a way, that heels could only stay on rudder pedals:

http://s013.radikal.ru/i323/1111/77/22428a8c3e3d.jpg

Yak-42 however had conventional pedals, but pilot still followed his technique from Yak-40, and erroneously applied brake pressure during takeoff roll. 44 died, 1 survived.

Official visual reconstruction by Russian investigation committee. Note there is brake-pressure indicator on the third row, on the left.



http://blu.stb.s-msn.com/i/B5/2EEAE7...2C1BFFD064.jpg