High Speed Turnoffs,How Fast?

[hoss]

I've had no luck finding it in the Australian Jeppesen Manuals.

I've tried the Tech Log Forum search.The results seemed to vary from country to country.

Does Australia have a Maximum Speed for the turnoffs and what is it? My understanding so far is an ICAO maximum of 60 knots groundspeed but I am unable to find this in writing. I also doubt the authorities would leave this one solely up to airmanship and as such am seeking reference.

If you know,your assistance on this subject will be appreciated.

Regards, Hoss :)

[Ausatco]

My experience is that the majority of pilots in the two major jet fleets (QANTAS and Virgin) use them at walking pace or go past them, so their benefit is negated. Not much point in worrying about maximum speeds, just do what they do, take your time. The aircraft on final can always go around.

Sorry to be cynical, but this is the way it is. Few aircraft use a rapid exit taxiway as a rapid exit, except for the regionals - they are exemplary. Why can't the majors get it right?

AA

[Keg]

Aus, mainly because the 'high speeds' in Australia aren't really high speeds. A high speed that has you doing a 180 turn about 100 metres into it is all but useless. The high speed off 27 and 16 in Melbourne, any of them on 16R and 16L in Sydney, etc, etc.

I've got no big qualms in using them but often they are about 100- 200 metres too close for the average domestic 767. That's why we sail past them.

Often doesn't help either when their is down wind on the runway!

[MoFo]

Use airmanship.
If you have to ask you shouldn't be using them.

[backspace]

Not sure how current my Jepps are, they havent been amended for 12 months, but have a look in the definitions at the start of the Introduction section. Page 6 High Speed Taxiway/Turnoff(HST).

[hoss]

Top work Backspace,you hit the nail on the head. I can't believe I missed that one and you'll be pleased to know that the page is still current from last year ;) .

Also thanks to the others.

Cheers Hoss.

[Hugh Jarse]

Can't comment on the regs, but for something like B9 (or U1) YSSY we'll do so at less than 50kt IAS. Above that, if the Capt is PF, the F/O is waiting to lock the flight controls (head inside), and if the FO is PF he will be waiting for the 50kt call, and waiting for the Capt to take the tiller (and more effective nosewheel steering). By the time we get to the main taxiway we are at 20-30kt groundspeed. That's without braking, and props in discing only. But you really need both sets of eyes outside, especially where you are joining or crossing another TWY.

It wouldn't be nice having a change of control while taking the rapid exit.

Personally, I have a look at traffic on the taxiways during approach, and if there is a potential conflict, slow to an exit speed at which I could stop with normal braking (before joining or crossing the taxiway) in the event that the conflict failed to stop before the rapid.

For the "Fish hooks" (T3, etc) I'm with the rotund one. ;) They are really of limited use as rapid exits in the true sense of the word, as you need to slow to almost walking pace prior to doing the 180.

[Ausatco]

Keg,

Thanks for your temperate reply to my intemperate post :) Much appreciated. I had a dose of the vapours last night when I posted because just about everything and everybody seems to be conspiring against us (SY TWR) providing a decent level of service. I won't steal the topic with details here - may post a new topic in D&G Reporting Points.

Never had a problem with your slowing down on RETs to take the U turn at the end - problem self-evident and understood.

OTOH, I wasn't aware that the positioning of RETs was marginal for 767s. Some of them are new, designed well after the 767 entered service. I assumed that they would be suitable in most circumstances. Given what you have said, the perpetual downwind factor that our esteemed politicians have imposed on us at SY assumes a new significance. Thanks for the info.

But what about B9 and A2 off 34L? Seems to me you have a longer landing roll before reaching those RETs than you do for the equivalents on 16R, and they merge nicely with the parallel taxiways. Can I ask, If you're going to use them, why not use them at speed, because very often I see aircraft slow to taxy speed on RWY 34L and then dawdle off via the rapid exit B9 or A2. Is it possible to adjust deceleration to take advantage of the rapid exit rapidly?

Jarse,

Thanks for your informative answer.

You raise a point that may be relevant for Keg exiting 34L via B9 or A2 - the presence of taxying aircraft on the parallel taxiway. Personally, I think that there should be a right of way rule in favour of the aircraft vacating the runway - rule to be assisted/modified by ATC instruction. However the taxying crew on the parallel taxiway would have to look over the shoulder to assess the confliction.

Jarse et al, can you realistically do that in a 737? 767? Dash 8?

AA

[Dehavillanddriver]

The rapid off 16R in Sydney used to be OK for the classic 73 but is pretty marginal for the NG - not so much the 700 but certainly for the 800.

The big turn just after you exit the runway doesn't help much either.

ML 27 has a rapid but it is about as useful as a hip pocket in a singlet for the NG - but OK for the classic.

See a pattern emerging here? The braking on the NG sux! The high weights don't help much I suppose - landing weight on the 800's is a tonne higher than the mtow for our 400- the whole 1 that is left!

[Hugh Jarse]

Ausatco, I can only speak from a Dash-8 point-of-view.

For example, (as you know) we regularly get instructions to "hold short B8" on taxi in from 34R.

I always thought (correct me, because the rules seem to be in a constant state of flux) that a vacating A/C had right of way, and who am I to argue?

I wish I had a $ for every time I wasn't told to hold short, only to see something lumbering off on B9 around the same time I was gonna cross it. I will give way every time and sort it out later :)

After all, we're only human....It's not a matter of blaming somebody (as some would want to do), but putting in place some SOP's to cover the lowest common denominator.

A STOP sign springs to mind. Then people will look before they cross the unbroken line. On second thoughts, most people can't even operate a car properly in the vicinity of a stopsign, much less an aeroplane..............................

[liquid_gold]

Ausatco, and others.....

This subject got me thinking about the comparisons of landing distances between the -300 and the NG, also the positioning of the rapid exits at SYD.

I opened a couple of books and came up with these comparisons F.Y.I. Don't shoot me down if I'm a couple of knots/metres/kg's out as I didn't want to waste the whole day on this. The distances quoted below are actual UNFACTORED distances (from 50' above threshold to stop), from Boeing manuals, using the following guidelines - Max Landing Weight, Nil wind, Max landing flap. We all know the consequences of tailwind, incorrect landing technique or touching down fast.

B737-300 Flap40 MLW(52 t) Vapp 139 Dist. autobrake 1 - 1900m, autobrake 2 - 1600m, autobrake 3 - 1200m, max autobrake - 750m.

B737-700 Flap 40 MLW(58t) Vapp 136 Dist. autobrake 1 - 2300m, autobrake 2 - 1900m, autobrake 3 - 1500m, max autobrake - 1100m.

B737-800 Flap 40 MLW(66t) Vapp 145 Dist. autobrake 1 - 2600m, autobrake 2 - 2200m, autobrake 3 - 1700m, max autobrake - 1250m.

To give you an idea of how you could describe the deceleration rates of the autobrake, I would say (my opinion) autobrake 1&2 would be considered "Normal" and passengers would not be aware of any heavy or significant braking. Using 3, the deceration becomes quite rapid, would make the average passenger wonder "what is going on ?" and max autobrake I would say is quite "startling" from a pilots perspective, so I'd hate to think what the average Joe is thinking down-the-back!!

Taking into consideration the lengths available (threshold 16R to B7 - 1550m, A4 - 2100m. Threshold 34L to B9 - 1950m, A2 - 2200m. Threshold 34R to U1 - 2000m.), it's not surprising that you may often see a B737 miss an exit that you may have thought was entirely appropriate. Unfortunately the NG uses significantly more runway than the classic.

Ausatco, I hope that answers some questions.:)

[Keg]

Aus, now your talking. B9 and A2 are better high speed taxi ways (although still a little on the short side for me!). The problem you have with those two are that a 767 at typical domestos weights and Autobrakes 1 and full reverse will be back to 60 knots well before it. Often a case of getting rid of both the brakes and the reverse well before it to take it at any speed.

I'll admit that watching an aircraft taxi forward as you come off the high speed is 'interesting' (especiallly for the Skipper who can't see them) and so I'm normally looking at them from before we get off the runway to let the boss know that they are stopping and/or slowing.

If B9 was about 200 metres toward the 34L threshold then it woudl be just about perfect. In fact, the high speed off 34R is pretty good at heavy weights and light winds (like this morning! ;) ) but a smidgin too far for a domestos 767 in anything more than about 10knots. Still, can't make them ALL perfect can we!! ;)

It is easier to ease the brakes off and get onto the high speed about 45 knots and decelerating then to get onto the brakes harder and make it. Punters don't like head butting the seat in front of them!

By the way, the high speed off 34 in Melbourne is pretty good at most weights (it's uphill which helps) but can be about 500 metres too far in the 35 to 40 knot northerlies they get down there at time! :D

Should mention too that the high speeds in BNE are a tad too close for the 767. Can do it 8 times out of 10 but if you miss them, you're on the RWY for a long time finding the next exit!

[TIMMEEEE]

Liquid Old son - a very informative posting and some interesting points.

The one thing I have noticed is that at Sydney alot of pilots will not use the high-speed correctly or aim to touch down at an appropriate point in the touchdown zone and using the appropriate selection of autobrake to achieve this.
Yes - you require 60 kts max on the high-speed but a pilot of average ability should be able to achieve this - especially taxiway B7(16R) or B9/A2(34L).

Brisbane has a much better set-up on both runways with well-spaced and positioned high-speeds.

My only disagreement Liquid is that Autobrake 3 and MAX although appearing harsh I found to be reasonably proportioned and did not ever upset the punters.The deceleration was smooth and remember the amount of braking action is also dependant on the amount of reverse thrust used to achieve the selected rate.
Sure the B737NG uses more runway but if you need autobrake 3 or even max in wet/harsh conditions remember it is there to be used.

The one thing I really hated were pilots who saw you use Autobrake 3 and comment on you being a "thrillseeker".
When asked if they've ever used it they always commented "NO".
After I got them to use it and see for themselves they were always surprised by the lack of harsh/uncomfortable decel rates they were expecting.

The only bit that is ever rough on the pax is when pilots disconnect the autobrake at an inappropriate time and you get the "jolt/jerk" so to speak.
Very bloody sloppy.

Autobrake is a very useful tool and should be used accordingly as the manufacturers intended.

Happy flying.

[liquid_gold]

Two things.

"Opinions are like @rseholes.... everyones got one, and each one is different from the other!!" - as good friend (proctologist) of mine would say. :D


One, (among many) differences the NG has with the 'classic' is the amount or force required to override the autobrake system with manual braking. Some more experienced pilots than myself have quoted figures in excess of twice the pressure required!

Taking this into consideration, it is exceedingly more difficult to create a gentle deceleration to taxi speed in comparison with the 'classic', and keep the punters happy.

Happy landings. OH, forgot, you don't do them anymore!!! :eek:

[TIMMEEEE]

Liquid - I believe you would be extremely content not doing landings either pal!
At least none of my landings are bad ones!

If the pressure required to disengage the autobrake is more than the classic then so what?
It's just a matter of experimenting to see what pressure is required and when to apply it.

Anyone can go from A to B and do a nice landing everytime but to me a true aviator will expand his abilities and knowledge of the aircraft by safely experimenting within the safe confines of the aircrafts limitations to find a better balance and what exactly may not only assist ATC but give the pax a smooth deceleration at the same time.

Dont be afraid to give it a go.

Sure opinions are like ar$eholes but some dont leave the DNA evidence behind!

[Dehavillanddriver]

Kiddies,

Play nice!

Timmee, I know what you are saying about the autobrake and the "jerk" when you disconnect it - but what Liquid is saying is quite correct.

The pressure required to release the autobrake is quite high - and it is different between aeroplanes just to make life more interesting.

It can be released by stowing the speedbrake, or by switching it off, but neither of those two options is optimal.

An interesting thing about it though is that you can override the brakes with significant pressure - applied smoothly and the autobrake will stay in. Give it a short jab - with less brake pressure - and it comes off..

Go figure..

In any event, getting the autobrake off is not as easy as people think it should be - and it surprises everyone when them come onto type, particularly those with lots of classic time..

[TIMMEEEE]

Thanks heaps DHD.

I'll now behave and share the sand-pit with LG!

Cheers.................

[Ausatco]

Thanks everyone. An interesting discussion and I have a better understanding of what you can and cannot do now.

Jarse,

Re vacating aircraft having right of way - I think it used to be in AIP, but some time ago I tried to find it and was unable, so I assume it is no longer the case. I wonder if it was an intended change or one that came about through editorial error. Common sense and airmanship would give it to them, but it wouldn't hurt for the requirement to be in writing.

Point taken re not being told to hold short of B8 then having to sort yourself out with someone on B9.

For most of us on Ground our standard response to your call on TWY L inbound is to protect the rapid exit B9 and have you hold short of B8.

Trouble is, the B8 hold is out of sight of the ground controller, below the window sill and you sometimes get forgotten, particularly if it's busy elsewhere on the aerodrome. Not a good outcome for anyone, particularly jets.

In order to avoid that, if we're not too busy most controllers will glance at the radar to see how far out the next arrival is, estimate that you will win at B8/B9 and clear you through to hold short of RWY 25. Sometimes it doesn't work :o - depends where you call, how fast you taxy, etc.

Personally, I think we should hold you short of B8 all the time and work on improving the scanning technique so that you don't get forgotten.

Feel free to give us a little reminder if there is enough R/T time. :p

Cheers

AA

[2FarCanard]

Hi speed turn off!?!?

You wake up one morning, after a big night out, next to an East German womens weightlifter with the hairiest legs you have ever seen and armpit hair you can plait. Now thats a hi speed turn off?:)