The great big "ask an airline pilot" thread!

bkehoe

billie1b wrote: »

Its the pin that goes into the nose wheel and bypasses the hydraulics, this enables the ground crew tug driver to have control of the wheel so he/she can steer the plane

737 operators will normally switch off the Hydraulic A pumps (the A system provides nose wheel steering amongst other things) as well and include telling this to the ground crew before they commence pushback.

billie1b

bkehoe wrote: »

737 operators will normally switch off the Hydraulic A pumps (the A system provides nose wheel steering amongst other things) as well and include telling this to the ground crew before they commence pushback.

Yeah the reason its switched off is to ensure nose wheel control and to enable both engines to be started. If the bypass pin is not installed, SOP is for a straight pushback and the crew are not allowed to start the engines until the ground crew have everything disconnected. Thats in my company, could be different in others

Jack1985

NW STRG DISC off in the A320 does the same job as the bypass also?

DownBeaten

billie1b wrote: »

Its the pin that goes into the nose wheel and bypasses the hydraulics, this enables the ground crew tug driver to have control of the wheel so he/she can steer the plane

Is this pin a standard size? Would the same pin that is used on an A330 fit in something like an ATR?

(Maybe this question should be on "ask an aircraft engineer" thread!)

Growler!!!

DownBeaten wrote: »

Is this pin a standard size? Would the same pin that is used on an A330 fit in something like an ATR?

(Maybe this question should be on "ask an aircraft engineer" thread!)

I'd say its aircraft specific. The ATR has a switch that turns the nose wheel steering on and off for pushback.

billie1b

DownBeaten wrote: »

Is this pin a standard size? Would the same pin that is used on an A330 fit in something like an ATR?

(Maybe this question should be on "ask an aircraft engineer" thread!)

As mentioned by Growler above, its aircraft specific, when we were using 737-400's, the bypass pin was smaller than the ones that we use for the 737-800's.

RobAMerc

folks - while travelling through ATL last week I spent about 2 hrs watching the aircraft movements. In that time I saw 2 go-arounds where on final the aircraft powered up and headed off again.

I thought this was an emergency situation and rare occurrence - is this not so ?


thanks Rob

billie1b

RobAMerc wrote: »

folks - while travelling through ATL last week I spent about 2 hrs watching the aircraft movements. In that time I saw 2 go-arounds where on final the aircraft powered up and headed off again.

I thought this was an emergency situation and rare occurrence - is this not so ?


thanks Rob

Not as rare as people think, they are not just initiated for emergency purposes, can be a number of reasons for it, just a few examples are poor visibility, excessive cross-winds, windshear, excessive energy (too high or too fast), aircraft in front not clearing the RWY quick enough after landing, aircraft on the RWY not departing fast enough and so on.
Its a practised standard procedure and most aircraft will be pre-programmed for it and it happens at the touch of a button, very safe and nothing to be worried about when or if it happens

Bigcheeze

RobAMerc wrote: »

folks - while travelling through ATL last week I spent about 2 hrs watching the aircraft movements. In that time I saw 2 go-arounds where on final the aircraft powered up and headed off again.

I thought this was an emergency situation and rare occurrence - is this not so ?


thanks Rob

In stormy weather conditions it wouldn't be unusual to see dozens of go-arounds at Dublin airport. Plenty of days like that during the December storms.

RobAMerc

thanks lads.
Our landing was a bit choppy but nothing wild so I doubt it was weather related.

The second one happened as a plane on a parallel runway was taking off, so it ended up with both climbing out side by side.
I must say and afternoon in ATL should be on every anoraks bucket list, it was fabulous !

adam88

Hi guys. Flew Shannon to stansted hint hint Wednesday last. I'm finding that the landings are harder and the braking is more excessive. Especially when landing at Shannon there was heaps of more runway left for the pilots to use in order to provide a smoother braking. From talking to other lay people there of the same opinion.

My question is, is this requirement to get off the runway quicker from the company in order to aid turnaround times or is it from the airport to free up for other aircraft.

I've often heard atc telling planes to clear runway expeditely.

IngazZagni

It would be a bit of both. In Shannon's case, there may be a good bit of runway left, but no taxiway so if they miss the exit it would mean they would have to do a 180 on the runway and go back the way they came. Making an earlier exit can reduce taxi in time and thus less fuel burn. I agree though, some guys can be a bit harsh on the breaks in order to make the first exit or whatever. It's uncomfortable for passengers. Sometimes though it's necessary as there is another aircraft breathing down your neck and missing the exit could mean the guy behind has to do a go around.

adam88

IngazZagni wrote: »

It would be a bit of both. In Shannon's case, there may be a good bit of runway left, but no taxiway so if they miss the exit it would mean they would have to do a 180 on the runway and go back the way they came. Making an earlier exit can reduce taxi in time and thus less fuel burn. I agree though, some guys can be a bit harsh on the breaks in order to make the first exit or whatever. It's uncomfortable for passengers. Sometimes though it's necessary as there is another aircraft breathing down your neck and missing the exit could mean the guy behind has to do a go around.

I'm no slim jim and I felt myself slide forward on the seat. I was sitting above the wing too so that didn't help but it was fair harsh

billie1b

adam88 wrote: »

I'm no slim jim and I felt myself slide forward on the seat. I was sitting above the wing too so that didn't help but it was fair harsh

During busy times in DUB, ATC will tell you which exit to take on the RWY as they can be stacked up tight. When they tell you they expect you to do it. Its funny, it never seems that harsh when your in the flightdeck.

SamAK

While we're on the subject of braking, is it just a case of reversing the engines? Are they simply idling at touchdown and providing zero forward thrust?

And how much juice do you give them when braking?

Sorry for the vague questions but I don't know a whole lot about the procedure

bkehoe

There's 2 main sources of braking in addition to aerodynamic drag created by spoilers (speed brakes) and the flaps. The use of the spoilers is very important to allow the wheel brakes to work as they disrupt the airflow over the wing meaning it ceases to generate much lift and thus puts the weight on the wheels.

First and most effective of course is the wheel brakes. These vary between aircraft types but many have carbon brakes and some may even have fans on the brakes to cool them. A standard 737 has steel brakes with no fans for example.

Secondly is reverse thrust. This is most effective at high speeds so its essential that a pilot deploys the thrust reversers after touchdown to get maximum effect. At lower speeds, while it will have some effect, its pretty much pointless so we would normally reduce to idle reverse thrust by 60kts.

Actual implementation of planning a landing depends on many things; the runway condition, head or tailwind, rapid exit taxiways, traffic following, aircraft weight, noise considerations, turnaround times, passenger comfort (as has been pointed out, people may wonder or worry if they suddenly slide out of their seats!) etc.

In my operations we try to use idle reverse when possible to conserve fuel and, very importantly at certain airports, to minimise noise disturbance to the area. We will try to make the first taxiway if its safe and our weight is light enough to permit it, as every minute saved taxiing is useful for us on a turnaround. Of course if the weather is rubbish, max crosswinds, etc, then we just want to stop as quick as possible so thats when one can even surprise themselves at just how quickly a large aircraft can stop.

In general though, minimising runway occupancy times is to everyones benefit.

Landing distances required are calculated from either computers or tables, and then we'd set an appropriate auto brake setting and whether to use idle or normal reverse to stop for the taxiway we want to exit at. In summer then cooling times for the brakes can be a consideration as well though in general around Europe its never been a problem for me.

SamAK

Great info and more mysteries cleared up, thank you bkehoe!

bkehoe

Oh, and you'd asked about the amount of thrust... Maximum reverse would be 80 - 85% N1. However this is not the same as the equivalent of normal as not all the airflow is being diverted. I've only ever used max on contaminated runways (or simulator!). The normal setting is around 75%.
Reverse thrust doesn't mean the engines reverse by the way. Different engines have different designs but they all essentially divert the bypass airflow from the fan forward using a complex series of ducts/vanes towards the rear of the engine.

For comparison, a reduced thrust takeoff for a light weight, long runway, in my type anyway can have a similar N1. Thus max reverse can use as much fuel as an engine at takeoff thrust.

Aphex

DeVore wrote: »

I always wanted to know if you sometimes, just occasionally, sit at the controls and go "brrruruuuuummmmmmmm brumm brumbrum" ... while pretending to drive it.





Cos I totally would!!

Planes have gears now?

SamAK

bkehoe wrote: »

Reverse thrust doesn't mean the engines reverse by the way. Different engines have different designs but they all essentially divert the bypass airflow from the fan forward using a complex series of ducts/vanes towards the rear of the engine.

Cool!


Another question based on what you've told me - Would reverse thrust be used to brake the aircraft in the event of an RTO? Or would it just be wheel brakes?

View Profile

Yes you would use reverse thrust up to maximum as well as braking and deploy the speedbrake.

smurfjed

Landed into LeBourget Paris, luckily the wind was favouring the long runway so we got vectored to that, turbulent approach. After landing we are rolling along the runway, choice of one exit taxiway or rolling to the end of the runway, as the aircraft was leaving again as soon as possible, we rolled along to the end in order to keep the brakes cool......
Next thing we know, ATC are asking us to expedite exiting the runway due to landing traffic behind us, problem was that he was speaking to that traffic in French so we didn't know that he was even there !! As we exited the runway we could see that the landing traffic was a 7X. Don't think that the tower was too amused with us, but hey, if you want us to know that you have traffic behind us, then either tell us, or speak in ENGLISH....

Thats my gripe for the week

conor_ie

I was going to ask if anything interesting had happened recently to any of the pilots that post here! Thanks Smurfjed!!

faceman

smurfjed wrote: »

Landed into LeBourget Paris, luckily the wind was favouring the long runway so we got vectored to that, turbulent approach. After landing we are rolling along the runway, choice of one exit taxiway or rolling to the end of the runway, as the aircraft was leaving again as soon as possible, we rolled along to the end in order to keep the brakes cool......
Next thing we know, ATC are asking us to expedite exiting the runway due to landing traffic behind us, problem was that he was speaking to that traffic in French so we didn't know that he was even there !! As we exited the runway we could see that the landing traffic was a 7X. Don't think that the tower was too amused with us, but hey, if you want us to know that you have traffic behind us, then either tell us, or speak in ENGLISH....

Thats my gripe for the week

Thankfully no harm came of it. In that instance if there had been an incident or incursion, who would have been at fault?

Jack1985

In that instance if there had been an incident or incursion, who would have been at fault?

I don't think ATC would let it get to that stage, predominantly in Europe you are only cleared to land when the runway is ''clear'', in the US however they can clear two or three to land at the same time and I believe in the US also its the crews responsibility to ensure its clear or possibly theres an equal share 50/50 responsibility.

Regards who would be at fault if there was an incursion I would think it would be ATC and the traffic that landed even though there was a danger on the runway (aircraft had not vacated) definitely not the crew who were on the runway.

Cessna_Pilot

smurfjed wrote: »

Landed into LeBourget Paris, luckily the wind was favouring the long runway so we got vectored to that, turbulent approach. After landing we are rolling along the runway, choice of one exit taxiway or rolling to the end of the runway, as the aircraft was leaving again as soon as possible, we rolled along to the end in order to keep the brakes cool......
Next thing we know, ATC are asking us to expedite exiting the runway due to landing traffic behind us, problem was that he was speaking to that traffic in French so we didn't know that he was even there !! As we exited the runway we could see that the landing traffic was a 7X. Don't think that the tower was too amused with us, but hey, if you want us to know that you have traffic behind us, then either tell us, or speak in ENGLISH....

Thats my gripe for the week

Had a go around myself in LTN last week because of some slow BIZjet drivers taking it a bit too handy vacating 26. Said BIZjet drivers being told to, and I quote "expedide to vacate B previously advised traffic at 1 mile" and them replying back in a very patronising and relaxed manner that they would :rolleyes: Quite a regular occurance there I believe. Said previous traffic being us, and them being told 3 times to not piss around on the runway! Amatuers!

Cessna_Pilot

Jack1985 wrote: »

I don't think ATC would let it get to that stage, predominantly in Europe you are only cleared to land when the runway is ''clear'', in the US however they can clear two or three to land at the same time and I believe in the US also its the crews responsibility to ensure its clear or possibly theres an equal share 50/50 responsibility.

Regards who would be at fault if there was an incursion I would think it would be ATC and the traffic that landed even though there was a danger on the runway (aircraft had not vacated) definitely not the crew who were on the runway.

Land after clearances are common at UK airports.

Jack1985

Land after clearances are common at UK airports.

Which airports? They don't issue such clearances at LHR the busiest in the UK, watched a documentary in July last year and aircraft were being cleared to land in LHR as low as 200ft AGL.

Cessna_Pilot

Jack1985 wrote: »

Which airports? They don't issue such clearances at LHR the busiest in the UK, watched a documentary in July last year and aircraft were being cleared to land in LHR as low as 200ft AGL.

Luton and Stansted to name two I'm familiar with. Issued only in the hours of daylight, for obvious reasons.

To quote;

When aircraft are using the same runway, a landing aircraft may be permitted to touch down before a preceding landing aircraft which has landed is clear of the runway provided that:
a) the runway is long enough to allow safe separation between the two aircraft and there is no evidence to indicate that braking may be adversely affected;
b) it is during daylight hours;
c) the preceding landing aircraft is not required to backtrack in order to vacate the runway;
d) the controller is satisfied that the landing aircraft will be able to see the preceding aircraft which has landed, clearly and continuously, until it has vacated the runway; and
e) the pilot of the following aircraft is warned. Responsibility for ensuring adequate separation rests with the pilot of the following aircraft.The phraseology used to authorise a landing aircraft to touch down before a preceding landing aircraft is clear of the runway is "LAND AFTER the (aircraft type)

Jack1985

Cessna_Pilot wrote: »

Luton and Stansted to name two I'm familiar with. Issued only in the hours of daylight, for obvious reasons.

To quote;

When aircraft are using the same runway, a landing aircraft may be permitted to touch down before a preceding landing aircraft which has landed is clear of the runway provided that:
a) the runway is long enough to allow safe separation between the two aircraft and there is no evidence to indicate that braking may be adversely affected;
b) it is during daylight hours;
c) the preceding landing aircraft is not required to backtrack in order to vacate the runway;
d) the controller is satisfied that the landing aircraft will be able to see the preceding aircraft which has landed, clearly and continuously, until it has vacated the runway; and
e) the pilot of the following aircraft is warned. Responsibility for ensuring adequate separation rests with the pilot of the following aircraft.The phraseology used to authorise a landing aircraft to touch down before a preceding landing aircraft is clear of the runway is "LAND AFTER the (aircraft type)

Cheers for that!