A320 Parking Brake -- Accident waiting to happen?

[GreenArc]

All,

The ON-OFF switch parking brake on the Bus seems a little too easy to use: easy to activate (very slight detent), exposed to hands and sleeves and feet etc., and totally separated from the normal braking system.

My best guess is that there's no "locked wheel" protection and a landing with the brake on would make a nice mess of the rolling stock.

Is there any type of visual or aural alert when the brake is inadvertently activated in the air? Anyone know of any incidents?

TIA.
GreenArc

"Just when they make something idiot proof, some new and improved idiot comes along." :oh:

[Busdrvr]

We had one case not too long ago when a crew was pushing back the Captain set the brake when he was cleared to start engine. He said he was reaching for the engine start switch (above the brake, but smaller), and set the brake by mistake.

[TopBunk]

Busdriver

Your account sounds like a bit of negligence. The engine start switch and the park brake move in different axes, the start switch moves forward/aft whereas the park brake rotates horizontally. That mistake is very basic and really does question the fundamentals of any switch or control movement. Clearly, it COULD happen to anyone, but SHOULDN'T, any control movement should be checked before operating it.

Still on topic, I must admit that I do prefer the Boeing philosophy (which I recall to be) of pressing the foot pedals and then applying the park brake to trap the pressure, rather than the Airbus philosophy of it being a switch - you have to be very careful applying the park brake on a 'bus when the ground crew ask you, ANY residual gspd will bring you to a very abrupt stop!

[PAXboy]

(not a pilot) If you think that the brake switch can be knocked 'on', could it also be knocked 'off'? Say, when on the stand and making checks before intended to release parking break?

[Mike Rosewhich]

TB. The parking switch may move in a different axis to the start switch but not the ignition switch and can be easily confused (it has happened to me).

In answer to the original question if the engines produce more than a given amount of thrust (I can't remember how much but it might be 1.15 epr) there is a master warning alert.

[GreenArc]

Mike,

if the engines produce more than a given amount of thrust (I can't remember how much but it might be 1.15 epr) there is a master warning alert

Probably not operative in flight though? Part of the takeoff warning system? Any warning in flight that you know of?

For any and all: since the Boeing system uses the normal brakes, would locked wheel protection be available while landing with the PB ON? The Airbus most assuredly bypasses that protection.

GreenArc

[SLT]

There is a Take Off Config warning if the Park Brake is set to park when either thrust lever is set to FLX/MCT or TOGA. Other than that, the only annunciation in the air (e.g. if someone accidentally set it to ON in flight), is an amber "PARK BRK" memo on the EWD. This has happened - a crew were "fiddling" apparently and set the brake to ON in flight. When they released it, the BPTI still indicated full pressure. Numerous things were tried, in the end as I understand it, the pressure bled off by itself and an uneventful landing was made. We had a notice sent out about it, asking us not to fiddle with the park brake in flight.
As for "an accident waiting to happen" - I've been on the bus 4 years and never heard of it happening accidentally. It was only that one time, which was a classic case of "what happens when I do this?"
:O

[GreenArc]

SLT,

Thanks for responding. Is the in flight "PARK BRK" message accompanied by an aural alert?

I posted an earlier question relating to the gear down BPTI check. Is that part of your company SOP?

I've been on the bus 4 years and never heard of it happening accidentally.

A couple issues ago, AW&ST had a letter from a guy who dunnit. There is apparently another crew who pioneered the procedure and he's looking to talk to them.

I haven't flown the Bus for four years, but it got me thinking.

GreenArc

[SLT]

As far as I know, there is no aural alert to accompany the amber memo. As regards the BPTI check at landing gear extension, yes that is part of our company SOP. We check for residual pressure on the BPTI and on the ECAM WHEEL page.
Having said all that, there is a procedure in the FCOM 3 which deals with the very situation you suggest. FCOM 3.02.32 p12 refers. A brief precis of it follows - As you know, the park brake uses alternate (Yellow) pressure (Blue on A330). If residual pressure is indicated on BPTI (Alternate) or ECAM (Normal), it suggests pressing the brake pedals several times to zero the pressure on the alternate system. If that doesn't cure it, it calls for you to select A/BRK MED, which will of course give priority to the normal (Green) system, thus cancelling out the alternate pressure. As long as the the normal system is in use (auto or manual braking), the alternate pressure will be cancelled out, thereby cancelling the problem. Any residual pressure on the normal system will be taken care of by the A/SKID. Therefore in theory, landing with the park brake set shouldn't be too much of an issue, as long as the A/BRK (or continuous manual braking) is used. (Assuming you have normal braking available in the first place!!)

Hope this helps!!! :O

[L337]

I had a fun incident on the A319. Taxi out at GLA, and was asked to make an intersection T/O. Out comes the performance book, and it was put down on the centre console, between us.

As I picked it up to put it away, the edge of the book, caught one of the "arms" of the park brake, and flipped it around to On.

We came to a very abrupt and embarrassed halt. No one hurt, only my pride.

L337

[PAXboy]

We came to a very abrupt and embarrassed halt. "Good afternoon Ladies & Gentlemen, this is the pilot speaking. Sorry about that sudden stop but we ... aahh ... were given conflicting information and thought it best to stop sharply just in case. Your saftey is always our number one concern, here at Pure Bull Airways." :E

[GreenArc]

were given conflicting information and thought it best to stop sharply just in case.

I always preferred the "small animal ran out in front of the airplane". :O

GreenArc

[GreenArc]

AAI
Preliminary Accident and Incident Data

IDENTIFICATION
Regis#: 682FE Make/Model: A306 Description: A-300B4-600
Date: 03/14/2004 Time: 1155

Event Type: Incident Highest Injury: None Mid Air: N Missing: N
Damage: Minor

LOCATION
City: FORT LAUDERDALE State: FL Country: US

DESCRIPTION
FEDERAL EXPRESS, N682FE, A306 ACFT, BLEW OUT 8 TIRES, OTHER CIRCUMSTANCES
ARE UNKNOWN, FORT LAUDERDALE, FL

INJURY DATA Total Fatal: 0
# Crew: 0 Fat: 0 Ser: 0 Min: 0 Unk:
# Pass: 0 Fat: 0 Ser: 0 Min: 0 Unk:
# Grnd: Fat: 0 Ser: 0 Min: 0 Unk:

WEATHER: KFLL METAR 1153Z 33008KT 9SM CLR 12/10 A3020


Preliminary reports are that the parking brake system was pressurized at touchdown. I don't know if the parking brake was on or not.

Interesting that this would occur just a couple of days after I started the thread. Anyone know if the A300-600 parking brake system is similar to the A320/330/340?

TIA

GreenArc

[Milt]

Handley Page Victor

It was the first Victor at Boscombe Down.

Because of the close fit of the U/C it was necessary to stop the wheels spinning before retraction.

Result was a stupid parlk brake lever covering the selection for the gear. Result - park brakes on in flight and released for landing.

Further result. Pilot doing a few touch and gos. After a go he went to select gear up and applied park brake. THEN changed his mind about the UP. The landing was a lulu with heaps of smoke and blowing tyres.

Forgotten what the fix was?

Come out of the woodwork you old and bold Victor pilots.

[Rimmer]

Not sure what the answer to this one is but it made me think.

There is no in flight aural warning if the brake is set

The a320 series parking brake like all the airbus family applies only 1/2 max pressure ( regardless what the guage reads ) and thats one reason engineers need their feet on the pedals for full power engine runs.

As to what would happen on landing if it were set my guess would be a very rapid stop

[GreenArc]

As to what would happen on landing if it were set my guess would be a very rapid stop

Actually, the stop isn't that rapid (but it is low on directional control). There just isn't much friction produced by either the blown tire carcass or the four main wheel rims as they grind down the runway. Now that's what I'd call a Rimmer. ;)

GreenArc

[Sidestick_flyer001]

In the beginining of this thread, Topbunk mentioned that due to the axis of movement of the Parking Brake lever, it should never be mixed up with any other lever on the center pedestal, except by negligence (his words ).

What cockpit egronomic designers must keep in mind is that much of our job is generally, if not mostly, governed by motor skills. Generally, and especially in times of high work load, our mind is resolving some actual problem, while our brain instructs our hands to do some routine mundane action.

Some time ago something quite comical happened, but it does really get you thinking. It ws one of those really rushed turn-arounds, in a very small regional airport I had never been before. I even had to go and pay airport charges. We were Ferry out, so everyone was waiting for me on my return, to depart.

Anyway, we started up and when cleared for taxi, I released the Parking Brake but the plane (320) would not budge (we were empty remember), I increased power, but still nothing. Back to idle and increased power agin, this time slightly more, but she just wouldn't move.

A quick glance to the E/WD confirmed my fears (and embarassment!). The damn Parking Brake was ON!! What had happened was that during the rushed pre-departure checks, the Parking Brake was mistakenly left OFF, and when cleared to taxi, purely by motor skills, I put the lever from OFF to ON, without even realising.

Quite an anti-climax, but really did get me thinking!!

[John Farley]

Sidestick makes a good point.

One day while joining the circuit I shut down the engine on a Harrier by moving the throttle (which has a fat handle) through to HP cock off instead of selecting max reverse thrust by moving the nozzle lever (thin handle) all the way back as I had intended. Lucky for me the Pegasus relights reliably and quickly.

In the wash-up with the pilots and designers nobody was surprised I managed to put my hand on the wrong lever as they are side by side in the same quadrant. What nobody could understand was how I got the HP cock off when this action requires a finger lift of a catch on the front face of the throttle, while to get reverse thrust you have to lift the whole nozzle lever up over a stop. Two totally different baulks.

My view was that once I had put my hand on the wrong lever then the habit patterns kicked in and I was going to do quite ‘automatically’ whatever my hand was used to doing with the thing it was holding in order to get it all the way back.

Just one reason (of several) why the left hand only has one handle/control/inceptor to operate on the JSF STOVL version.

[DCDriver]

Sidestick,
Be assured that you are by far not the only one to have done that!
Until I met airbus, I had always been on types requiring two actions to set the park brake, (eg) depress toe brakes, pull nice big park brake lever. Nobody got confused.

Since I've been on the 'bus I have commenced pushback with the brakes set; thought the brakes were "on" when they were actually "off" ( & vv); and set brakes to park while still moving slightly. Pretty careless, you might say, and perhaps there was an element of that. But in defence, I have never done any of these in 25 yrs of flying other more "tactile" types.
So, IMHO the airbus park brake switch is perhaps not "an accident waiting to happen" but it could have been designed better.