A320 declares "Emergency" because of autobrake fult

[Tee Emm]

An Air Canada Airbus A320-200, registration C-FFWN performing flight AC-416 from Toronto,ON to Montreal,QC (Canada) with 145 passengers and 5 crew, was on short final to Montreal's runway 24R when the crew received a "AUTO BRK FAULT" ECAM message and decided to go around. The crew requested to enter hold clear of other traffic while working the related checklists, declared emergency about 20 minutes later and landed safely about 30 minutes after the go around.

The Canadian TSB reported pin F on the brake servo valve #1 connector 15GG-A was contaminated. The pin was replaced, operational tests were satisfactory thereafter

A Mayday for an autobrake fault?

[swh]

What if the mayday was for low fuel while they were working the problem?

[Airmann]

The issue may have been that they were on short final. Might not have wanted to carry out the landing without being sure that manual braking was working.

[Jonty]

No, it just means you have to press the pedal yourself!

[Gauges and Dials]

"AUTO BRK FAULT" on the ECAM, means that the computer is saying, approximately, this:

"Hey! There's something wrong with the auto braking system. Or maybe there's something else wrong with the brakes that, based on the sensor data available to me, I'm interpreting as an auto brake fault. But it could, of course, be something else. Maybe there's nothing at all wrong with the brakes at all, or maybe you'll find a surprise when you land, and the brakes are either locked or nonfunctional. how should I know; I'm just a dumb computer, doing the best I can with a couple of sensor readings..."

prudence, and all that...

[Peter G-W]

I think Airbus would disagree with you there. It means the Autobrake function is lost. If there was a fault with BSCU 1 or 2 or Normal Brakes or Alternate brakes it would tell you. It used to be taught that this failure would come up if the Autobrake selector button was “stabbed” rather than selected in the approved Airbus fashion. Have seen it happen a couple of times but not for a while now.

[Ritam]

I can't find any more details on this, but perhaps while working the autobrake checklists, they received additional brake-related indications? Given that the ultimate fault was traced to something on the brake servos, and not something to do with air/ground sensing, it seems like it could have affected more than just the autobrakes.

[Jonty]

To be fair, non of us were there.

[Gauges and Dials]

Originally Posted by Peter G-W

I think Airbus would disagree with you there. It means the Autobrake function is lost. If there was a fault with BSCU 1 or 2 or Normal Brakes or Alternate brakes it would tell you. It used to be taught that this failure would come up if the Autobrake selector button was “stabbed” rather than selected in the approved Airbus fashion. Have seen it happen a couple of times but not for a while now.

In theory, you are of course absolutely correct. And in theory, there ought to be no difference between theory and practice. But the difference between theory and practice is greater in practice than it is in theory. ;-)

[vilas]

Mayday for AB is ridiculous. GA may be the strict interpretation of no ECAM below stabilization altitude but there is absolutely nothing to work out the problem or in ECAM. With normal and alternate brakes with antiskid available just land. Manual landing distance is shorter than AB anyway.

[CanadianAirbusPilot]

Originally Posted by Jonty

To be fair, non of us were there.

FWIW I fly for the airline in question and I would say a good portion of us (WAG of 20%) don't use auto brake on landing. Some only use medium or off, others will always select it but not use it for long, and others will use it down to their exit or 30 kts. Long story short pilots at this company, the drivers should be very familiar with using their own brake pedals and I would assume that the emergency was brought on by either a) fuel or b) a follow on problem. None of us where there and it indeed seems a little funny to declare a mayday for this problem.

[Dan Winterland]

This fault can be triggered by a number of issues. Last time I saw it, it was due to a brake unit failure, so we had to apply a Landing Distance adjustment. This will come up on the ECAM. If you are on short finals, then really you should go around. If they were short of fuel, I would say it was appropriate.

[parabellum]

This fault can be triggered by a number of issues. Last time I saw it, it was due to a brake unit failure

Dan that doesn't sound right. If there is more than one fault shouldn't the system have shown a brake unit failure, being more serious than an auto brake failure?
If the message, 'Auto Brake' failure could cover other system failures, including ones that can effect the landing distance surely it is wrongly named? Something that generates a higher level of urgency, drawing attention to possible performance degradation. On the Boeings I have flown if an Auto Brake fail message came up on finals we just switched Auto Brakes to off.

[Airbus_a321]

A318/A319/A320/A321 FLEET PRO-ABN-32 P 3/32 FCOM

BRAKES AUTO BRK FAULT Applicable to: ALL

Ident.: PRO-ABN-32

L2Autobrake function is lost.

L1Crew awareness.

Ident.: PRO-ABN-32

STATUS
INOP SYS

AUTO BRK

That‘s all. End of procedure.. CREW AWARNESS, only !!!!
go around, with given facts in first posting? Negative! My2cents

[Airbus_a321]

Originally Posted by Dan Winterland

This fault can be triggered by a number of issues. Last time I saw it, it was due to a brake unit failure, so we had to apply a Landing Distance adjustment. This will come up on the ECAM. If you are on short finals, then really you should go around. If they were short of fuel, I would say it was appropriate.

Probably you mean this event, which includes AUTO BRAKE FAULT as inop sys. But this failure and ECAM is totally different to BRAKES AUTO BRAKE FAULT only.


BRAKES A/SKID NWS FAULT OR ANTI SKID/NWS OFF Applicable to: ALL

Ident.: PRO-ABN-32

L2Either both BSCU channels are failed, or the A/SKID & N/W STRG sw is OFF.

L1MAX BRK PR.......................................................... ............................................................ ..1000 PSI L2Monitor brake pressure on the BRAKES PRESS indicator. Limit brake pressure to approximately 1 000 PSI and, at low ground speed, adjust brake pressure as required. Avoid landing on an icy runway. Ident.: PRO-ABN-32

L12 STATUS MAX BRK PR.......................................................... ..1000 PSI LDG DIST PROC...................................................APPLY • If Y SYS LO PR BRK Y ACCU PR ONLY CAT 3 SINGLE ONLY See (1)

INOP SYS

CAT 3 DUAL
ANTI SKID
N/W STRG
NORM BRK
AUTO BRK

(1) Note: Automatic rollout is not permitted as specified in QRH,Refer to QRH/OPS Required Equipment for CAT2 and CAT3.

@parabellum is right

[Dan Winterland]

No, I did mean BRAKES AUTO BRAKE FAULT. the OP mentioned the registration C-FFWN which is MSN 159. This is a very old Airbus with the original brake system architecture and without the ABCU. The procedure is very different to that described above, which is from a newer MSN. A320s built from about 2006 have the newer system. I have included the excerpt from my company's FCM PRO ABN BRAKES for these older aircraft. I saw this twice on my 12 years and 9000 hours on the A320 and it's not a straightforward procedure - and this crew knew it was something more complex that a simple auto-brake fault.

FWIW, the new Airbus procedure is to land with auto-brake on every landing, but of course this is not in every company's SOPs.




The AUTO BRAKE FAULT alert may be due to a failure of the autobrake mode itself, or to a brake released condition. The flight crew should, therefore, be prepared to counter a possible slight lateral drift at landing, via the rudder.

STATUS

LDG DIST PROC........................................................ . APPLY
CAT 3 SINGLE ONLY

INOP SYS
CAT 3 DUAL
AUTO BRK
NORM BRK

[FlightDetent]

Thanks DW for the research, enlightening read.

[RVF750]

Fascinating. I have a French car. when I drive over a bump I get a parking brake fault, sometimes the rear boot open warning too. It's just a dodgy pin on the left front ABS wiring! Never trust the French!!

[Cak]

@Dan Winterland

First of all, it's not true that auto-brake is mandatory according to Airbus SOP. It's still AS RQRD

Regarding the brakes, old system is just a little bit different but not that much that it requires too much brain storming. It has no ABCU and some controls are interconnected little bit differently to HYD system.
Procedue is straight forward as you copied it from your FCOM. Only difference is that you loose NORM BRK and that's why you have to calculate LDG DIST PROC. You have fully functioning ALTN BRK. But with old system pilot needs to restrict brakes pressure manually to max 1000 PSI. On new system ABCU does it for you.
LDG DIST is some 10% more for DRY or GOOD RWY if memory serves me good.
If the RWY is extremely short or contaminated and you want to recalculate your LDG DIST to be sure, it makes sense to do a go-around, but if they declared emergency only because of that, it's ridiculous.

[msbbarratt]

Touch and Go?

If they had carried on with the original approach, could they not have simply turned it into a touch and go if they found the brakes to be inoperative when they pushed the pedals?

I suppose there was a chance that's the brakes could kinda half work, enough to prevent returning to flight. I can see an argument for not touching the ground so that you can get the airport prepped for a tricky landing after a second approach.