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Antiskid Off and foot position on rudder pedals

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Antiskid Off and foot position on rudder pedals

Old 28th Jun 2015, 18:22
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1jz
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Antiskid Off and foot position on rudder pedals

Does any of the aircraft manufacturer direct specific foot position on the rudder pedals during landing to avoid inadvertent brake application?
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Old 28th Jun 2015, 19:27
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Which manufacturer are you looking for? there's recommendations to slide feet up for braking, for max and consistent braking action, and to make sure both feet are positioned equally if you fly an aircraft with toe stops...(a few cm off can lead to asymetrical braking...check temps) but right now I can't think of recommendations to avoid inadvertent braking for landing. For t/o, apply pressure with your heels unless you need to brake. Just thinking out loud.

Last edited by deptrai; 28th Jun 2015 at 19:45.
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Old 28th Jun 2015, 20:08
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deptraj you are on the right track.. I know this too since the basic flight training sessions but, I am looking for some documented evidence for this and especially if it is for a multi turboprop or jet. May be an ops procedure with antiskid off.
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Old 29th Jun 2015, 08:33
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Does any of the aircraft manufacturer direct specific foot position on the rudder pedals during landing to avoid inadvertent brake application?
Surely the correct technique should have been demonstrated to you during your very first dual flight with an instructor on a Cessna 150 or similar light aircraft. Toes on the bottom of the rudder pedals at all times unless you need to apply them; in which case slide your feet higher to depress the brake pedals. That normally applies to all aircraft with toe operated brake pedals

However an early version of the Boeing 737 FCTM stated:
" Prior to touchdown place feet on the instep bar (rudder bar) of the brake pedal with toes away from the brake pedals. Be prepared for manual braking immediately at touchdown or to override the autobrakes if required"

A still earlier version of the FCTM displayed a pictorial example. It showed the pilot placing his heels on the instep before touch down with his toes arched back away from the top of the pedals to prevent inadvertent application of the brakes. Anyone who has tried this technique can attest it is very uncomfortable and unnatural which is maybe why Boeing deleted the diagram in later versions of the FCTM.

Currently the reference to foot position on the rudder pedals has been deleted in the FCTM's. In other words, foot position on the pedals is taken as elementary flying knowledge; so why state the obvious.

That said, it is not uncommon to observe pilots in the simulator resting their feet too high on the rudder pedals causing inadvertent touching of the brakes during the take off run. This increases the take off distance and invalidates V1. This is displayed on the instructor operating panel where brake pressure is monitored during the landing roll. It also shows up during the take off roll if brakes are used inadvertently.
.
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Old 29th Jun 2015, 11:47
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Thanks Centaurus, that is the info I am looking for.. Do you happen to have any document available that u can share? And if not then which 737 documents should I look for? The 300 series or even earlier? Actually I need to be having a documented proof.
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Old 29th Jun 2015, 12:01
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Actually I need to be having a documented proof.
Proof for what? As Centaurus says, in aircraft with normal brake pedal configuration (e.g. toe brakes), one uses toes for rudder control until touch down and then after nose gear touchdown or when required for braking slides his feet slightly up so toes can reach the brake pedals.

Some info from 737 FCTM - nothing on feet position, although common sense would dictate extremely careful use of the procedure above:

Braking with Antiskid Inoperative
Antiskid Inoperative - Landing
When the antiskid system is inoperative, the following techniques apply:
ensure that the nose wheels are on the ground and the speedbrakes are
extended before applying the brakes
initiate wheel braking using very light pedal pressure and increase
pressure as ground speed decreases
apply steady pressure.

When the antiskid system is inoperative, the NNC tells the flight crew that they
should not pump the brakes. This is because each time the brakes are released, the
required stopping distance is increased. Also, each time the brakes are reapplied,
the probability of a skid is increased.
Flight testing has demonstrated that braking effectiveness on a wet grooved
runway is similar to that of a dry runway. However caution must be exercised
when braking on any wet, ungrooved portions of the runway with antiskid
inoperative to avoid tire failure.
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Old 29th Jun 2015, 12:09
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Well I think I should rephrase it as document rather than saying proof.. I need to refer to the document in one of my papers so that is why I m looking for it.
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Old 29th Jun 2015, 23:51
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If you get it WRONG for example.
( A really bad example from the past and done without a simulator !)

An empty ferry to Southern Africa, weather clear, a light headwind, a long runway, touchdown in the right area and speed.

One Tyre burst
Six Tyres scuffed
One Main wheel and one Nose wheel in Flight Spares
Two days delay while spare tyres were ferried out on a special flight ( empty ) from UK
Repaired a/c flown empty to UK
Some 40 hours of empty flying. ( The Company lost money on this.)

The Captain PF ( LHS) had 2000 hours on type and 10000 total at a guess.
This S F/O ( RHS) had similar levels . But had failed to see/ notice or comment on where the Captains feet were.

LT
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Old 2nd Jul 2015, 09:52
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airbus rudder pedals are designed to have the feet up on the pedals, not heels on the floor. Steer with your heels, brake with the balls of your feet.
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Old 2nd Jul 2015, 15:24
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TP

The a/c in #8 was in fact a B, a Bristol Britannia.

Different makers have had their own ideas - at the time.

Another A, Austers, had separate heel brakes on Autocrats, as taught by their Chief Test Pilot in 1948.

The S/F/O's feet in # 8 were flat on the floor. They were avaiiable if needed, but could have only pushed - not pulled, to reduce brake pressure had that been required.

Watching the brake pressure gauges on Touch Down might be an unusual scan. I suspect that fairly little brake pressure might have been sufficient to do the damage to the tyres on touch down.

IIRC trials had attempted to see the effect of "spinning up" the wheels to improve tyre wear. But this required more spin speed control/ touch down speed than then possible.

LT

Last edited by Linktrained; 2nd Jul 2015 at 15:28. Reason: bits
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Old 3rd Jul 2015, 21:06
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Originally Posted by TyroPicard
airbus rudder pedals are designed to have the feet up on the pedals, not heels on the floor. Steer with your heels, brake with the balls of your feet.
Ref please ?
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Old 3rd Jul 2015, 21:42
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ref please

The closest you will get to a reference is FCTM normal ops, pre start: "The rudder pedals must then be adjusted to ensure the pilot can achieve both full rudder pedal displacement and full braking simultaneously on the same side."

This can be construed to suggest you should have heels on the pedals, as it is hard to achieve both full rudder and full braking simultaneously with the heels on the floor.

I believe this is an A vs B thing, different design philosophy, and I believe Linktrained hinted at that

Last edited by deptrai; 3rd Jul 2015 at 23:15.
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Old 4th Jul 2015, 01:33
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I remember many moons ago flying a sector on an old classic 747 with a captain who was a senior checker, also in the observers seat was an even more senior checker who was doing a surprise standards check.

All went well until after shutdown when my captain says that I should have had my heals off the floor during the final part of the approach, his reason being so I could apply manual breaking quicker after touch down.

I disagreed (insulent FO) and after a bit of discussion, the standards checker intervenes and says he believes that my method was the correct one. Happy days ........ off to the pub for a beer. BTW full marks to the captain, he did not hold a grudge.

Now what is the preferred method on the Bus types, I have no idea!
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Old 4th Jul 2015, 02:11
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Foot position

Offchocks
Both positions i.e. heel on the floor or on the peddles with toes curled back are accepted techniques. You can choose what you are comfortable with. It mattered on archaic aircraft like 747 classic without A/brake and rudder not connected to nose wheel, had you tried low speed reject with poor braking action RW you would have understood the checker. But any modern aircraft is fitted with these it doesn't matter much.

Last edited by vilas; 4th Jul 2015 at 03:00.
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Old 4th Jul 2015, 04:27
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villas
Our old classics had nose wheel steering, but I know what you mean by low speed rejects which can be a handful at the best of times, you have to be quick if 1 or 4 fails or its for the grass you go! Anyway it does not matter to me much anymore since I recently retired.
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Old 4th Jul 2015, 07:16
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'on the peddles with toes curled back are accepted techniques'


Really not, you should only have your heels off the floor when you are applying the brakes deliberately.


Not 'trying to avoid to'


That is asking for trouble.
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Old 4th Jul 2015, 08:34
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Stilton, a lot of people have been taught differently on the Airbus, and fly it that way (and such discussions are pointless without a reference to a specific type)
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Old 4th Jul 2015, 09:34
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If you think so then you don't have to but it is done and can be done. You can check with the manufacturer.
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Old 4th Jul 2015, 11:37
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It depends on your anti-skid system logic.

In the old days, we had to wait for the wheels to spin up to aircraft speed on landing before we applied the brakes, else there was a chance that anti-skid logic could lock the wheels.

According to FCOM DSC-32-30-10, Anti-Skid System;
"The speed of each main gear wheel (given by a tachometer) is compared to the aircraft speed (reference speed). When the speed of a wheel decreases below approximately 0.87 times (depending on conditions) reference speed, brake release orders are given to maintain the wheel slip at that value (best braking efficiency).
In normal operation, the reference speed is determined by the BSCU from the horizontal acceleration of ADIRU 1, 2 or 3.
In case all ADIRUs fail, reference speed equals the maximum of either main landing gear wheel speeds."

So this particular anti-skid system will not apply the brakes until the wheel speed is 0.87 of IRS sensed ground speed - so there is no problem with landing with your feet resting on the brake pedals.

If ant-skid was US, then I would keep my heels on the floor until the nose wheel was on the ground.

Last edited by Goldenrivett; 4th Jul 2015 at 11:44. Reason: typo
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Old 4th Jul 2015, 15:52
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Landing without revese ( none fitted ) OR improved braking system ( not yet available) by F/O (CPL) in LHS ( where the nose wheel steering was avaiilable, if a little heavy)

On landing at Blacbushe the brakes did not work....

Until the ASI was down to 70 kts (?). Power had been reduced th IDLE by F/E ( who was facing aft... It was a Hermes 4a ) And Full flaps gave some aeodynamic drag, which must have helped.

Asked Tower whether C54 which had just landed had reported braking problems.
" NO Problems"

C54s were known to have a lower speed " over the hedge" than the Hermes.

Chief Piilot arranged for us ALL to have Perfomance "A " training - a new requirement. Various treads of tyres were fitted to the fleet.

We read that various NEWer aircraft were having wet performance tests

Much later when landing at Manston which was not usually busy, and after a "Practice Emergency GCA " ( right down to the ground, just in case we REALLY, REALLY needed it. We never did.)
F/Es " cleared the plugs" by setting Zero boost whilst the a/c was stationary, held by the brake pedals. Brake pressure was slowly released to see when the a/c started to move, . Normally this might be about 50 psi out of the possible 400 psi.

LT

Last edited by Linktrained; 4th Jul 2015 at 16:13. Reason: Manston
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