when to use brakes?

[class-e]

Having spoken with some fellow instructors here in YSSY, the topic of when to use brakes (considering no requirement to vacate runway immediately exists) came up.

My policy has always been not to use brakes on the runway,and to keep the nose wheel off the ground for as long as possible on landing.
A few reasons for this are:
1/ saves wear and tear on the brakes/tyres
2/ teaches the student what to do in the case where the brakes fail.
3/makes the student think more about the landing and roll-out, helping to ensure a "main-wheels first" landing
4/stops the student slamming the nose wheel onto the tarmac immediately after the mains have touched!(as they have a tendency to do!!!)

what is your opinion?

[This message has been edited by class-e (edited 05 December 1999).]

[squeakmail]

Yeah, valid points...save wear and tear..etc.

Sad you didn't mention the other side of the equation...don't assume that because you are ahead and below you can spend as long as you like coasting along the runway whilst the guy on short finals does a go around waiting for you to clear.

Give the for and against the argument...otherwise..good comment (IMHO).

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LIVE in peace...or REST in it!

[BEagle]

I hope that none of my spamcan students use the brakes on a PA28 like Lufthansa - and probably most other airlines - seem to. Mains on, nosewheel on, full reverse and stand on the anchors to make the first turn-off - then dawdle for a while waiting for the ground pattern to be clear. I agree about the infuriating people who drift along just above the runway forcing go-arounds by following traffic - and the restriction on landing with one already on the runway at unlicensed aerodromes is a pain in the whatsit!!

[class-e]

Sorry people, maybe I wasn't clear about that...
I mean that "when there is no requirement to exit the runway promptly"....be it a professional courtesy or a request from the tower....or someone is up your bum~ I did not mean that you make someone else go-around!

If you have the runway to yourself, and there is enough of it...why not use it?
:)

[Tinstaafl]

I teach to always test the brakes - lightly - immediately after the nosewheel is placed on the runway. Better to discover the problem with maximum runway left in front.

Also, when braking is commenced, to use the brakes a little more firmly than seems necessary. Not to the point of skidding, nose diving etc, but it's better to find that you didn't actually need all the braking power that was used, than to discover at the end of the runway you should have used more when it there, just waiting to be used...

I suppose the 'correct' amount of braking I try to teach is one where a relaxation of brakes is necessary to avoid stopping just short of the chosen taxiway etc.

[This message has been edited by Tinstaafl (edited 05 December 1999).]

[askcv]

I checked the brakes in a Macchi just after touchdown then used aerodynamic braking until approaching the exit taxiway, to discover that they had blown the hydraulic line to one wheel during the test (the line was hanging and fluid was found on the runway). With no fluid I had no brakes, normal or emerg, the barrier was inop, and not enuff runway to get airborne again. Pretty rough ground off the end of the runway, I found.
The back-seater was a fellow QFI and he had the canopy open and my seat pins ready for me when the nose bobbed up after we came to a stop.

The moral? Dunno!

[Swamp]

Can't say I really agree with testing the brakes immediately upon touchdown. I guess either you have a requirement to use maximum barking or you don't. I have always found that checking the brakes as part of a pre landing check is more than adequate - although even this method is known to have 'locked' the brakes on occasion only to then blow a tyre on touchdown.

Sometimes holding the nose up after landing is even more effective than braking. I remember the problems I used to have with a P68. The brakes would get red hot and be totally ineffective but holding the nose up in the old dog of an aeroplane would slow it down nicely. Unless there was a requirement to exit the runway quickly or stop on a short runway then it was company policy to avoid brakes whenever possible (in this aeroplane).

The same argument applies to reverse thrust. Should you go Beta Range when there is no operational requirement? Two manual I have for the same aeroplane from different airlines specify opposite requirements!?! What makes more sense from an operators point of view?

I am a big fan of the 'Rapid Exit'. I think it's silly that at most GA airports (in Australia anyhow) you have to do a full 90 degree turn to exit the runway which essentially means you have to slow down to below taxi speed on the runway before you turn.

[Hugh Jarse]

Teach 'em both ways. Show them what the A/C is capable of, but commonsense and experience will usually determine the technique.

Does anyone still check the toe-brakes with the pre-landind drills? That often will alert you to the first signs of trouble.

It can be useful to hold off the nosewheel a bit longer with soft fields, too.

[vila legend!!!]

hugh jarse - I have to agree with you - as an aircraft owner, operator and instructor ( for 25 yrs)for the benefit of all three BUMFOH is still the best!

Have you ever seen the tyres of a C182 RG after even light braking immediately after landing? Not pretty in fact not even round any more!

[Wee Weasley Welshman]

Hmmm, I teach my students to apply braking action as soon as possible and to then apply continuous but modulating brake pressure to bring the aircraft to a halt - usually well before the runway end. Here is my thinking.

I operate generally from a 800m RW with very un-pleasant overuns therefore there is a reduced safety factor.

That aside if the brakes have failed I want to know ASAP. I have encountered lose reservoir caps that have resulted in loss of hydraulic fluid after - say - stalling sorties. Early diagnosis will allow use of parking brake etc.

The risk of Aquaplaning a light training aircraft is very low. I also find braking action deteriorates on an aircraft if the brakes are not regularly used. The pad surfaces change, the discs corrode and the system generally becomes less effective if rarely used in anger.

Undercarriage tyre and wheel problems in their early stages tend to show up during braking - you know, odd clunks and vibrations.

If the student rarely does any serious braking then when they come to the short field exercise they are underconfident and it is a whole new skillset for them to learn. They may also get a nasty suprise when they first visit a shorter field than they trained on. Surely its better to equip them for the worst case even if you happen to have a 2400m by 90m 'strip'. Running off the runway is the most common accident at my field.

Although the majority of students learn to fly in the summer they have year long licenses - what happens when they take their mates up on a lovely clear frosty New Years day and then land on the old familiar runway only to find it strangely slippery as hell and the end approaching.

I find that students very commonly over-relax after landing and do not properly control the aircraft right down to fullstop. I can only think that letting the aircraft bleed off speed at its leisure exacerbates this trait.

As the aircraft slows down it loses directional stability - most obviously in a crosswind. By using a good braking action the time during which the aircraft is most exposed to directional instability is reduced. I can only feel that keeping the nosewheel off the ground down to 20kts is inviting a crosswind gust to do its worst.

There are runways in the UK with significant downhill gradients. With very little headwind and an unfamiliarty with the field a student taught to let speed bleed off at leisure could end up taking a ridiculous amount of time on the runway which would suprise other aircraft/ATC.

By teaching them to always brake with a modulating pressure you are preparing them for the day they land on a very wet or grass runway and skid the aircraft. They will automatically be easing off the pressure with my technique. It is very very very hard to come off the brakes when you are skidding. I don't believe they will have the ability to do so - particularly in this day of ABS on every car, its just not a skill in use anymore and its against your instincts. Doing this every time also exercises the nose oleo which should keep it healthy and diagnose seals wearing out etc. It also acts to stop nosewheel shimmy. It is less comfortable for passengers though.

The pinciple of using brakes fully and early is preparing the student for the larger aircraft he/she will often want to get checked out on once they have a bit of time on their license. Many of the above arguements get stronger if you take bloggs out of his solo C152 at a large training airfield and into a PA28 Warrior on a shorter airfield with 4 mates, luggage and loads of fuel...

*When* the student later in life has to put the aircraft down in a field due to an engine failure do you want him to a) have to remember to brake fully with skill and judgement even though the adrenalin is going like hell or b) land carrying out his/her normal, ingrained landing actions.

Brakes are specifically designed and engineered for the job of stopping the aircraft. The wear and expense is pretty marginal on light training aircraft.

I agree that at many places on many days and in many aircraft the brakes are just a luxury. However that same student trying to get onto my runway, today in something like a Warrior with some mates on board needs those brakes as much as he needs wings and he needs to be damned competent in their use. We should prepare them for more than the skilltest.

Thats my thinking anyway.


WWW

[The_Messiah]

When to use brakes?
When you need to stop.
Anyone who has to go around is usually too close to the aircraft in front.

It's simply a question of airmanship....does anyone remember that word?

[de La Valette]

Let me put it this way. If you owned the aircraft and this means you pay the bills for wear and tear on everything, including braking systems, I suggest that you would apply the brakes judiciously and only when necessary. If you don't own the aircraft then you probably apply the brakes less than judiciously.

[Charlie Foxtrot India]

If there's plenty of runway left, and no reason to stop quickly, why use brakes at all?
Let the aircraft slow down to taxi speed by itself.
I once witnessed someone who had cross-hired one of my aircraft slam the brakes on after landing. You could hear the squeal of tyres, and the aircraft slewed around 90 degrees.
Sure enough, flat spots = new tyres. Not cheap, and completely unnecessary if the pilot had exercised some airmanship. He still had more than half the runway left in front of him. He denied it all, unaware that I had been at the holding point watching the whole thing. Just as well, because with the spats on the wheels, the flat spots could otherwise have gone unnoticed.

Cost: Tyres AUS$125.00 each
Labour $150.00
Down time $500.00

When taxiing you should always have an "escape route" in case of brake failure anyway.




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[Wee Weasley Welshman]

There's a lovely picture at my school of a PPL piloted aircraft in the hedge at the end of the runway due to a floaty landing followed by insufficient braking:

Cost: 20,000 pounds sterling

WWW

[class-e]

That's a lot of money to pay for a picture isn't it?

seriously though....in that situation a go-round is the option...not heavy braking!!!
The question is "when you have sufficient runway.....etc"

[Wee Weasley Welshman]

Yeah but the frame was very high quality.

I do not believe green PPLs have developed the airmanship skills to judge after the end of a 45hr course and therefore should be taught to err on the side of extreme caution as a matter of habit.

WWW