Plane to jetway: Can I have my door back?

[gtf]

At DFW Wednesday morning, inbound AA 777 rolled back 200 ft (really? isn't that a typo?) just before passengers started deplaning. You know where the door isn't now.
Sky Talk: American 777 loses door at D/FW (http://startelegram.typepad.com/sky_talk/2010/06/american-777-loses-door-at-dfw.html)

[A and C]

Follow the link and find another forum that has a resident idiot posting rubbish.

But the photos are interesting.

[hichachoc]

Parking brake? Whatever happened to chocks? :confused:

[SeenItAll]

TV news story says wheel chocks were not set, and plane rolled back 200 feet while passengers were disembarking, snapping off the door against the jet bridge. Amazing that no one was hurt.
See: Door Flies Off American Airlines Plane (http://news.yahoo.com/video/dallascbs11-15750646/door-flies-off-american-airlines-plane-20373978)

[pattern_is_full]

Rolled backwards 200 feet? I guess that's a ramp that is really a ramp!

[fireflybob]

I have had one occasion when the chocks slipped on a greasy ramp after the brakes had been released! Fortunately we noticed as we were conducting post flight checks etc and were able to reapply the brakes before the a/c had rolled a short distance. Luckily there was no damage other than the workload of filing an occurrence report at the end of a very long day!

[AnthonyGA]

What sort of incline does this ramp have that it would cause an aircraft at (presumably) a complete stop to roll backwards 200 feet?

[SeenItAll]

Even though a wheel or axle may seem to be completely rigid, there is an awful lot of torsional energy stored in one that is braked to a stop -- especially if the final braking was severe. My guess is that this energy was held in by the final braking, and was only released when pressure in the hydraulic system bled away after the engines were shut down. It probably took a couple of minutes before enough force to overcome the static friction of the tires was accumulated, but after it did, the roll began.

[Pinkman]

OK, I'll bite. I can visualize the torsional energy thing. But when the brakes are released the torsional energy would actually make the aircraft go forward until it is dissipated, not backwards. So either its the rocking out of snow effect (where going forward against an incline makes it easier to go backward etc.) or its more simple - its on a wicked slope and they forgot to chock the airplane. I go for simple.

P

[SomeGuyOnTheDeck]

I'm not sure I understand the 'torsional energy' idea. Blown downwind perhaps?

I find the '200 ft' roll a bit implausible too. Wouldn't someone have noticed? :confused:

[planecrazi]

What was the "off-blocks" time Captain???:}

[jjeppson]

DGS is used at DFW gates. No guideman required so chocks not installed until ground handlers show up. Parking brake valve malfunction and A/C rolled backwards. I imagine some procedures will change.

jj

[protectthehornet]

I remember when there were lots of competent mechanics waiting for a plane to park...and that chocks in was a signal from the ground crew...then and only then would you release the parking brakes...even then it was a gentle process and if there was any roll, bam the brakes were back on.

[p51guy]

My good friend checking out in a DC10 at the same airline as a captain released the handle before the brake and it rolled into the jetbridge. He had been in the right seat so he forgot about how to properly set the brake.
**** HAPPENS.

[WhatsaLizad?]

A couple of questions for the Euro crews that use the parking systems which I've seen in places like Madrid,

Is there a requirement for a member of the ramp crew to man some sort of a stop signal button as an aircraft approaches the gate? Is there also a requirement to chock an aircraft after parking with the auto system? Is an aircraft allowed to park using the auto system without any ramp personnel being present at all?

[Dont Hang Up]

OK, I'll bite. I can visualize the torsional energy thing. But when the brakes are released the torsional energy would actually make the aircraft go forward until it is dissipated, not backwards


Yes it would. And the release would have to be sudden to generate an impulse strong enough to set the aircraft rolling. A slow bleed-off of brake pressure and the aircraft would simply ease forward a distance commensurate with the amount the axle was twisted. I would guess mere centimetres.

[JW411]

I thought that all you experts out there would realise that most parking bays are built on an upslope of about 2%.

Why?

It makes it so much easier for the tug to push the aircraft back and it also makes it easier for those aircraft that are capable of doing so to power back by using reverse thrust without using a tug.

This has been discussed many times in the past on pprune (wake up those of you who are sat at the back of the class).

[WhatsaLizad?]

I thought that all you experts out there would realise that most parking bays are built on an upslope of about 2%.


Where? The UK?

Maybe at some brand new well designed terminals in the US, certainly none that I can think of. I think with lowest bidder contracts, we're lucky of the slope is +/-2% in any direction :rolleyes:

[Silvertop]

Everywhere I go around europe the operator won't connect the jetbridge until the chocks are in place

Silvertop

[A321COBI]

clearly the lously ground crew were having a fag :mad:

[OverRun]

The slope of the apron / parking bay is generally 1% or slightly less. The minimum we aim for is typically 0.4%. I think 2% is quite excessive; as a comparison, the runway transverse slope maximum is 1.5% for larger airplanes, and that is quite steep. To quote ICAO Annex 14:

3.13.4 Recommendation.— Slopes on an apron, including those on an aircraft stand taxilane, should be sufficient to prevent accumulation of water on the surface of the apron but should be kept as level as drainage requirements permit.
3.13.5 Recommendation.— On an aircraft stand the maximum slope should not exceed 1 per cent.

I can understand how the aircraft rolled 200 feet then stopped. That is the depth/length of a typical large aircraft parking bay. The drainage is designed for water flow down to a defined low point or line (such as a drainage channel), and it is quite likely that the parking bay sloped down at 1% and outwards from the terminal to the low end at the end of the bay (which acts as a drainage gully) and then the pavement sloped up again to the next high point such as the centreline of the taxiway. The aircraft stopped at the bottom of the slope.

To get the water away from the low point, the end of the bay is either sloped transversely so the water turns 90 degrees and flows away, or there is a slotted drainage inlet running along the width of the bay.
Cheers
Overrun

[EW73]

I understood that the parking brake, when set, is backed up with a 3000 psi brake accumulator, and will, subsequent to the securing the relevant hydraulic system, maintain sufficient pressure to hold the brakes sufficiently applied to have these sorts of accidents not occur!
I'm talking in the vicinity of 18 hours here!!

ew73

[Capn Bloggs]

JW411,
(wake up those of you who are sat at the back of the class).
At least I was awake during my English classes... :cool:

[TURIN]

JW411

There are a number of stands at my local (UK) airport that slope towards the terminal building. One in particular is such a dramatic slope that local procedures have been developed to ensure chocks are in immediately the beacon goes off.
Doesn't always save the day though, just before pushback, tug attached, the chocs were kicked out by the ground staff and the a/c rolled forward catching the door on the airbridge. The brakes had failed on the tug!! As the man says, Sh1t happens.

In twenty odd years airside I've witnessed three a/c roll when no chocks were in. One was my own stupid fault and we got away with it. :O

Another, a DC10 rolled 40ft (away from stand forunately) when the crew assumed chocs were in and released the brakes. Again, fortunately no one was hurt and as the brakes were released so soon no equipment had time to get anywhere near.

[misd-agin]

Taxiied by the gate yesteday. Slight slope for about one plane length, at which point, at least from my perspective, the slope increased.

In general the ramps seem to slope up to the terminal. The worst, fortunately not that common, are the 'downhill' gates. Nothing like trying to pushback when the ramp's damp and the tug can't move the aircraft because of the slope(LAX comes to mind). Yes, the new, lighter, cheaper tugs. Field tested, just not on damp, 'uphill' gates. :ugh:

[muduckace]

Bottom line at any operator is a pilot should not release breaks until he has verbal or hand signal confirmation that chocks are in place. Mis-communication or a blatant screw up I am sure it will remain an internal matter for AA.

Sort of cool pic though of the door sitting in what appears to be quite a normal position on the jetway.

[muduckace]

Here is a point to consider, aircraft full of pax, crew is out of the cockpit, by the time anyone makes it into a seat this bird is rolling, hitting the brakes could cause more injuries than a collision. The aircraft is likly to sit on it's tail.

[muduckace]

A couple of questions for the Euro crews that use the parking systems which I've seen in places like Madrid,

Is there a requirement for a member of the ramp crew to man some sort of a stop signal button as an aircraft approaches the gate? Is there also a requirement to chock an aircraft after parking with the auto system? Is an aircraft allowed to park using the auto system without any ramp personnel being present at all?


I have had gates with these systems and hate them, pilots are told they can procede at their liability, there is a green and red clear/not clear indicator. Marshalling gave me the ability to bring an aircraft on a gate at a safe speed, i used to get cowboys barreling in on these gates all the time and there is nothing I can do but throw the red light on in an unsafe condition.

[jjeppson]

The newer terminal ramps are built with a slight slope away from the terminal. This is to prevent any fuel spill from flowing into/under the terminal.

jj

[Grond]

As a youngish FO I remember sitting on the flight deck when the flight engineer appeared outside the cockpit window . "Must be going to clean the windows" I thought. Then I realised he still on the steps and was shouting "Set the :mad: park brake!"

I think the trailing edge ended up inches from the hi-loader.

It was always useful having an FE around. Sorely missed.

[5552N0426W]

I suppose different countries have different SOP's but basics would be - a/c on the gate, engine shutdown, ground chocks in, anti col lights off then airbridge applied.

No doubt there will be a lot of questions for the poor person who put on the bridge and cleared door opening for pax disembarkation.

If chocks were on nose and main legs what happened then?

Nobody hurt though.

:O

[ThreadBaron]

I am having trouble imagining any part of the jetway being rigid enough to remove a door, least of all the bellows extension. The photo on the link shows no visible damage to the jetway.

Maybe the jetway manufacturer should start making door hinges.

[dixi188]

I suspct that the design of this door hinge is with shear pins/bolts for just this event. Otherwise much more structural damage would occur.

[misd-agin]

muduckace - "Bottom line at any operator is a pilot should not release breaks until he has verbal or hand signal confirmation that chocks are in place. Mis-communication or a blatant screw up I am sure it will remain an internal matter for AA. "


Brakes were not released. Obviously no chocks(SOP at self parking gates). SOP in that there is no requirement for a ground crew to be present, ergo no chocks.

No mis-communication or blatant screw up except for the managers that bought off on 'self parking' without a requirement for ground crew to chock the a/c.

[gas path]

dixi188 has got it in one!:ok: The design of that hinge assy is such that it contains the damage to the hinge and not the door or surrounding structure:8
The usual senario though is lifting of the door by the airbridge:suspect:

[lomapaseo]

misd-agin

Brakes were not released. Obviously no chocks

I don't understand these facts:confused:

I'm probably missing something so how does/did the aircraft move if the brakes were not released/

[Airbubba]

Here's the official version of events from the AA 777 fleet management:

Aircraft 7AD, while parking on D33 at DFW, experienced parking brake pressure failure, which caused the aircraft to roll backward, shearing the open 2L door when it contacted the jetbridge. The crew had completed the parking checklist and were preparing to exit the aircraft when they were notified the A/C was rolling backwards. The Captain quickly returned to his seat and applied brakes. The first application reportedly had little resistance and did not slow the aircraft. His second application had no resistance with pedals fully depressed. The aircraft continued to roll aft into the middle of ramp exit 122 and almost into the terminal B ramp. Once momentum slowed, the aircraft rolled forward toward terminal D finally coming to a stop.

The parking brake can lose pressure at anytime. With 3,000 lbs of pressure, the parking brake is designed to hold pressure for a minimum of eight hours. If the parking brake valve or any other pressure component fails, pressure can be lost very quickly - four minutes after the parking brake was set, in this case. We are working with Ramp Services to ensure chocks are installed as quickly as possible after arrival. Modern terminal ramp design requires a slope away from the terminal to ensure fuel runs away from the building in the case of a spill.

When the parking brake lever is set, the outboard parking brake lever position switch connects power from the hot battery bus to the parking brake valve (PBV). The PBV is then driven to the fully closed position. Once closed, an internal microswitch within the PBV applies power to the parking brake valve close relay. This relay then connects power to illuminate the parking brake set light on the NLG [nose landing gear] and provides a signal to AIMS [Airplane Information Management System] to display the parking brake set memo on EICAS [Engine Indicating and Crew Alerting System].

We must ensure the parking brake set messages is displayed on EICAS after the parking brake is set. This is our only assurance the parking brake valve is closed. A check of accumulator pressure should also be included in your scan after the parking brake is set to confirm sufficient brake pressure is available. Chocks are the only way to prevent aircraft movement if pressure is subsequently lost after parking.

Jim Dees B777 Fleet Captain


American explains about that door-ripping Boeing 777 | AIRLINE BIZ Blog | dallasnews.com (http://aviationblog.dallasnews.com/archives/2010/06/american-explains-about-that-d.html)

[Capn Bloggs]

We are working with Ramp Services to ensure chocks are installed as quickly as possible after arrival.
Sounds like a pretty cheap-charlie system if you can't afford to have a $200m, 200+ pax, 200+tonne aircraft chocked as soon as it stops on a bay. :confused:

[Fil]

A BA 777 rolled back from the terminal at LHR just after the PAX had disembarked a few years ago, Capt also floored brake pedals with no effect so they declared a Mayday and started the engines which was the only way to arrest the roll. Can't remember how far it went.

We've been through stages of requiring chocks in place before any disembarkation, to not needing them so long as they are put in place before the crew leave the aircraft. As you can imagine the policy changed again.

Also not all airlines release the brakes once the chocks are place either.