TCAS unserviceable
 

Situation this morning: After pushback, TCAS becomes U/S.MEL says this can be deferred for 10 days for repairs.We are planned to fly A to B through four different countries FIRs, arriving at a fairly busy airport.Can you operate unrestricted? Are we grounded? The aircraft is INSTALLED with TCAS version 7.1 (latest version).

I think you've answered your own question.

relevant thread
http://www.pprune.org/tech-log/45947...tive-rvsm.html

maybe not the only one didn't search any longer.
https://www.google.com/search?q=tcas...www.pprune.org

should list most threads maybe replace rvsm with mel :)

(this thread has some nice quotes: http://www.pprune.org/tech-log/373309-tcas-again.html)

Unserviceable up to 10 days seems to be the norm. Germany is the one oddball state out there as it allows a maximum of 3 days for all aircraft including overflights. Of course the question is: how can they determine if anyone has their TCAS inop and for how long has it been inop? If one lands in germany however and runs into a SAFA check the aircraft will be grounded until TCAS is repaired.

Must admit as soon as TCAS fails I tend to start looking round the cockpit for something else that has failed. First suspect is the Rad alt.

Its not officially broken until you land at the other end after you have pushed.

And with TCAS I wouldn't be surprised after you landed and you did a black aircraft reboot it didn't self heal.

It depends on the aircraft type your flying. If its a retro fit TCAS installation or if its a installed as new and fully integrated into the aircraft data buses. Its not common its "just" the TCAS processor that's failed it usually something else that links into it. 80% of my issues with TCAS failures have been something to do with the rad alt. And failing one of them properly with a CB pull (on being told to by the B2) has unconfused its little brain and its started to work again.

For the OP....

1. Have you dispatched ( definitions seem to vary)?

2. If dispatching iaw with your DDG then what does that say?

Our's has a ten day limitation, plus a statement saying dispatch not allowed if "procedures require it's use" so it might be time to dive into the books and look up the rules for each en-route FIR/State of overflight..:oh:. and for us there's a ban on dispatching from a main Maintenance base into or over those parts of Africa that require use of the In-Flight Broadcast procedure.....

Apart from Germany, Switzerland is another FIR to be very careful with TCAS u/s. Maybe they even prohibit entry altogether, irrespective of DDG / MEL provisions?

Our Flight Dispatch team used to be the decision maker in charge for TCAS failures.

Surely it's the same principle as immunisations, we all benefit from herd immunity.

One aircraft with TCAS inop is protected by everyone else's working, what you don't want is too many aircraft in your airspace with TCAS inop, probably the reason for the restrictions in some states.

TCAS
 

Thanks for the replies.I guess what im looking for is the individual state policy on this type of situation.Years ago when TCAS first came on the scene, airspace was not as busy as it is now, and TCAS was clearly not a mandatory item.Along came RVSM changing the equation, but generally still no mandatory TCAS at least in RVSM.It seems though that as with most things in aviation, the evolution of procedures keeps developing and perhaps this is reflected in the various regulators policies regarding, in this case, TCAS status.There appears to be a wide variation in policy, something that makes knowing how to operate problematic.

I believe there are a handful of airports where TCAS is mandatory. I know my company has a rule for EDJA but I thought that was due to the amount of glider/VFR traffic.

Airliners were flying without any issues way before TCAS was on the drawing board.

I don't see the issue. It just means more situational awareness is required on descent and approach from both yourselves and ATC.

Very much depends on the state you are flying over. UK AIP ENR 1.6 Para 2.4.1.1 requires that you fly to a place where TCAS can be fixed by most direct route if it fails before departure.

That reference is if the transponder has failed.

You can operate with TCAS inop in the UK for up to 10 days on commercial aircraft.

RTN11, I would be grateful if you could explain the difference between failed and inoperative?

The MMEL has a standard entry for TCAS of 10 days but the MEL should be amended by the operator to the more restrictive requirements applicable. In the case of your company MEL it would appear that this has not happened.

Not much of a difference between failed and inoperative.

However, a huge difference between a transponder and TCAS. One might be required for the other, but they are completely different things.

Denti, good spot and my bad. I was confusing this with a conversation I had regarding transponders. Apologies all for the duff gen!

.......apart from occasionally hitting each other you mean?

As the cause of any problems we have is usually moisture ingress in the coax cables or upper antenna, its not normally a quick fix.....hence the MEL alleviation.

There is no simple answer to this question, as you indicated, due to individual State variations, TCAS versions, RVSM or not, MEL, etc...
Once you've pushed back and started moving under your own power, MEL no longer applies, however, it may be prudent to refer to it regardless.
What you DO need to check prior to departure is whether or not you are allowed to ENTER airspace in each case, that can best be done by letting your OPS/FLIGHT PLANNING department run the flight plan again without TCAS installed and ascertain if this is mandatory. Engineering can assist in determining the MEL but is unaware of operational restrictions.

"Installed"
 

Following your logic Skybob, surely re-issuing the Flight Plan with the statement "TCAS not installed" is not correct.TCAS is INSTALLED but just today (and possibly for 10 more days) it is simply INOPERATIVE.So your flight plan can say perhaps "TCAS installed but is temporarily U/S"?

An interesting aside is the definition of "DISPATCH".One poster said "you have dispatched once your aircraft moves under its own power".However in some countries this definition is "once applying thrust for takeoff".