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-   -   Coasting onto stand. (https://www.pprune.org/tech-log/522108-coasting-onto-stand.html)

tripilot 24th Aug 2013 07:04

Coasting onto stand.
 
I'm not sure if this has been brought up on here before - if so sorry.
I'm a LTC captain on 737-300/800 so know a bit about the aircraft but I'm a bit bemused by crews that shut down both engines and 'coast' onto stand. I've noticed it as a passenger only and nobody has ever suggested it to me on the flight deck.
Single eng taxi is regularly used by myself and others but never a no engine 'drift' having turned onto stand. Obviously the APU will supply elec and hydraulic power and should that fail the brakes still have accumulator pressure but.......IS IT A GOOD IDEA?
As always I default to what Boeing say and in this case it doesn't offer any advice but on the other hand it doesn't say not to do it. Mind you it doesn't say not to shut down both engines in flight and drift down from overhear the field to save fuel - presumably because its NOT A GOOD IDEA!
I've only seen and heard about this on one airline (based in the Emerald Isle), does anyone else do it? If so why? Does it make such a huge difference to fuel costs or shut down time? Does that outweigh the potential safety / embarrassment factors? Does your FO swoon and say "wow capt. you're amazing doing that, one day ill make up my own procedures too"!
Opinions please.

OutsideCAS 24th Aug 2013 07:31

One engine taxi I can understand to a degree - coasting onto stand with no engines, well that sounds daft to me and assuming this is a supposed fuel cost saving measure (and maybe a few seconds in time)?. Perhaps the baggage handlers could start to crack open the holds as the aircraft enters the stand, the catering truck moving in before the aircraft has stopped and the fuellers attaching the hose on the taxi in.:hmm:

grumbles69 24th Aug 2013 07:32

I do know that its not a good idea to shut the engines down too early, say at 37000 ft!! :eek:

BARKINGMAD 24th Aug 2013 07:36

GLIDE APPROACH TO STAND.
 
After the accident, what will the crew be saying to the CP to justify this?

Some ramps have just that, a ramp before the ideal parking position, requiring considerable thrust application to reach the ideal parking spot, which may be jetty determined but also ensure the tail of the 'frame is not encroaching on the taxiway.

I can only assume this manoeuvre is an example of "showing off", and sooner or later the practitioner(s) will come to grief. I and no one with whom I have operated have NEVER EVER considered it as a professional, disciplined and safe method of parking and IMHO it is fraught with risks and danger and should never be considered as a way of parking 89 million dollars of aircraft, let alone the 189 hapless SLF in the back. :=

BOAC 24th Aug 2013 07:41

+1. Had one of those 'ever so slick' Captains once who used to do it and actually ran out of motion short of the stand. Choice of restart/tug or disembark with stairs at rear door since the jetty blocked forward steps - tee hee............did I larf........

Agaricus bisporus 24th Aug 2013 09:30

At the point when a ground collision/fod risk is at it's highest and four eyes should be focussed firmly outside yet some fool's shutting down an engine and, presumably, watching the EGT to see it really does shut down cleanly?

What's the point anyway? This indicates a bit of a Walt mentality to me, and grossly unprofessional too. It is completely inappropriate.

rog747 24th Aug 2013 09:40

BMA DC-9's used to do quite often on to the bravo cul de sac at Terminal one LHR in the 1970's and 80's and coast in to B2 or B4 stands

also on the odd occasion powered back off stand using reverse...

Sleeve Wing 24th Aug 2013 10:03

>>>>> BMA DC-9's used to do quite often on to the bravo cul de sac at Terminal one LHR in the 1970's and 80's <<<<<

Apart from maybe one smartarse, no they didn't, and even then it was shutting down just as brakes were applied for final stop……..never "coasting".

……..and reversing off stand was forbidden because of ingestion, "bucket" damage and the possibility of lifting the nose wheel off the ground. Did you ever really look at the amount of rubbish on the Bravo stands ? :ugh:

tripilot 24th Aug 2013 10:04

I'm sure these chaps are only choosing to do this in situations that they are very familiar with i.e. without an up slope, no airbridge, maybe self stopping, cute FO that needs to be impressed etc... However I really would like to know if this is something that has been suggested within the airline to save fuel and time. Further to this, the same low cost airline only uses 1 minute cool down time for its engines rather than the Boeing time of 3 mins - sad I know but I've timed it!

rog747 24th Aug 2013 10:10

lol sleevewing,

i possibly agree with your observations of certain maverick(s) lol...but i was merely saying what i saw as i worked there...

as for reverse off yes of course it was not standard nor approved but it happened on odd occasions for whatever reason...

merely all this is an aside please don't get ratty by it

it was along time ago LOL

and if you worked for Midland too i am sure we met!

Lots of very nice characters both flying and on the ground at LHR

Sleeve Wing 24th Aug 2013 10:22

Hi Rog,

No offence taken…….
and, yes, I was on BMA's DC9s from the start………. ;)

Great company in those days, as you say, mainly because of the peeps.

Uplinker 24th Aug 2013 10:31

Whatever the reason, this (coasting onto stand) is a stupid and extremely unprofessional thing to do.

Sadly, extreme fuel saving (if that's what this is being done for) is a particularly beguiling genie which has been let out and can never be put back.

Owing to the fact that fuel saved can be projected by multiplying by the number of sectors flown per year, even a 10kg saving can be made to look like say, 200,000kg per year. Fuel costs $1 per kilo, so abracadabra! you've "saved" $200,000!

This is a classic demonstration of how statistics can be manipulated to show whatever you want them to. Because you haven't saved $200,000, you've saved $10. But it has led to all airlines single engine taxying, not turning all the aircon packs on, not having aircon on at all while on stand, and not putting on the heating/cooling before the passengers start getting on - leaving the cabin crews to work in awful conditions, and other stupidities.

As an illustration of how far this could go; why not turn off one engine at the top of descent? I mean, you're going down anyway aren't you? Then at say 10,000 feet, fire it up again for the landing. :D

Don't laugh, this sort of thing could happen.

The way round this of course would be to charge the proper ticket price for the flight :hmm:

dubbleyew eight 24th Aug 2013 10:33

you'll feel a real hero if you kill one of the groundies because he stood in the way not knowing that a silent aircraft was rolling down on top of him.

make some noise. it warns people.

nitpicker330 24th Aug 2013 11:10

I've seen it done in the 737-300 a few times with no problems in Oz.

Obviously the Captain only did it at locations that were conducive to a successful outcome. Generally at small quiet outports in Oz such as OOL ROK etc where there wasn't any Aerobridge just a downhill run to stop in front of the Marshaller.

Stop being so tight assed and live a little folks.

Centaurus 24th Aug 2013 11:20


Stop being so tight assed and live a little folks
You certainly have a way with words. "Coasting" displays poor airmanship at it's worst. If it is meant to save fuel, you may as well recommend taxiing with the packs off after landing. That saves fuel too, and the cabin air won't have time to stink before the doors are open.:mad:

MaxReheat 24th Aug 2013 12:37

'Stop being so tight assed and live a little folks

It's being 'tight assed' that enables the airline industry (generally west of the Gulf) to enjoy its enviable safety record that 'tight assed' professionals have strived to achieve. With that attitude your cutting the odds on ever making the 'old' bit of the 'old and bold aviator'.

Why anyone would want to shut down all engines before coming onto stand is a concept beyond my comprehension.

Tight assed - you bet, as and when required - assuring a long and accident-free career to date.:ok:

Capn Bloggs 24th Aug 2013 12:46

Powerback
 
Still approved...

POWERBACK
General
The powerback maneuver can be an efficient means for the airplane to
depart the gate and transition to the taxi phase. There are, however,
several factors of safety and passenger comfort that must be considered
before commencing the maneuver and during the maneuver itself. These
considerations are as follows:
• Flight and ground crew must have completed an appropriate
powerback procedures training program.
• Powerback can be performed only in approved ramp areas.
• Thrust reversers on both engines must be operative.
• Ramp must be clear of contamination.
• There must be no more than moderate precipitation.
• Use minimum reverse thrust required.
• Do not use brakes while the airplane is moving rearward.
• Both pilots should have their feet on the floor during the powerback
maneuver.
• Verify all personnel and equipment are clear of engines fore and aft
prior to initiating movement of thrust levers.
:ok: :ok:

captjns 24th Aug 2013 12:53

To quote Scott Crossfield, after coasting into a hangar door.

"Chuck Yeagar may was the first pilot to break the sound barrier, but I'm the first to break the hangar door."

Saw a dumb A$$ try it in a 727. Shut all engines down, the APU took a crap:eek:, and guess what... The Brake Accumulator was sho:eek:t. Off in the dirt she rolled. By the graces of the Sky Gods, there were no passengers on board, no buildings, vehicles or personnel in the way. I guess the crew forgot about the brake interconnect:rolleyes:. Oh well:{.

Basil 24th Aug 2013 13:20

No argument - it's unprofessional.
Neither have I ever taxied a twin on one - except once after landing with a failed engine.;)

Edited to add: Runup to leaving employ of HM, on initial IR and having offered CAA IRE control of little twin to fly back, he decides to impress me by cutting both donks as we approach the refuelling pump which has an upslope.
The (almost) inevitable and we stopped short. As he restarted one to complete positioning, I recollect hoping he wasn't so embarrassed that he'd take it out on me at the debrief. He didn't :ok:

nitpicker330 24th Aug 2013 13:44

You are all hanging on too tight.....:8

Get a life you lot, more important things to fix first other than rolling the last 100' on to stand I would have thought. :confused:

( things like, stabilized approach criteria and not crashing into Sea Walls, landing on the nose wheels first, stalling the Aircraft at FL390 etc etc etc, those really will kill you :sad: )

Suppose you wouldn't buzz the tower either!!:}


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