TCAS again

[avionneta]

hi,
Anybody knows what happens when two aircarft are in conflict having both their TCAS in TA only position (remote case of both aircraft experiencing engine failure for instance)
thanks

[Nightrider]

In this scenario both aircraft will receive the "Traffic Traffic" with the associated visual display. That's it.

This is an unimaginal situation as both aircraft may be in the drift down process to reach the single engine service ceiling, ATC will have cleared their individual path before.

Since both are not RVSM compliant anymore ATC will provide a minimum 2000 ft cruise separation.

But....never say never....:=

[Denti]

Just to clarify, why are they no longer RVSM compliant? As far as i know TCAS is not required for RVSM, only a certain version if you have it. MEL repair interval is in most EU countries 10 days for TCAS, only in germany and i believe france is it reduced to 3 days.

[Nightrider]

Denti,

this is a major discussion I have since about 3 years, it will obviously never end until the law makes it understandeable.

To certify an aircraft for RVSM operation you will not need TCAS; based on this, your assumption is very correct.

However, aircraft need to have a TCAS system these days and this makes it difficult. It goes down to ATA 34-40 and some CAA have superseded the MMEL of some manufacturers to have the AOC MEL showing that RVSM compliance is only given if an operational TCAS system is available.

You may have to dig a little in your MEL, most probably there is only a sentence in ATA 34-40 similar like "only required if enroute or approach procedures ....."

According to RVSM requirements your MEL should contain a special dedicated section, most probably somewhere in the preliminaries section (or whatever your AOC holder calls it) and the requirements are listed there. A tad confusing sometimes, without TCAS I have to stay out of RVSM.

Hope this helps.

[Otto Throttle]

I would suspect that having all engines operating and an ability to maintain assigned flight level is an RVSM requirement.

Perhaps you would like to re-read the post fully and in context.

:ugh:

[Denti]

According to our MEL we are certainly allowed to enter RVSM airspace without a working TCAS. As we are based in germany we have to repair a u/s TCAS unit within 3 days which is an excemption to the european 10 day repair rule.

By the way, Eurocontrol has some very nice info freely available on their webpage, the following excerpts are directly pulled from there:


Flying with an inoperative ACAS II is permitted, including within RVSM airspace, provided it is done in accordance with the applicable Minimum Equipment List (MEL).

The MEL for TCAS II throughout Europe is Class C - 10 days (excluding the day of discovery). Operation under the terms of the EASA-OPS 1 TCAS II MEL has been agreed and accepted by the ECAC Member States. JAA TGL 26 (which is still applicable) states that TCAS II "may be inoperative provided the system is deactivated and secured, and repairs or replacements are carried out within 10 calendar days. Note: Local Authorities may impose a more restrictive rectification interval days.

However, one State in Europe applies a more restrictive requirement: in German airspace the time period during which TCAS II may be inoperative is reduced to 3 days (refer to German AIP GEN 1.5 para. 5). This applies to all aircraft.

In Europe, there is no requirement to notify ATC or to make a remark in the flight plan about TCAS II being inoperative. There are different requirements outside Europe, e.g. India, where ACAS equipage needs to be stated in the flight plan. Please refer to the individual States authorities for more information.


“The procedures to be applied for the provision of air traffic services to aircraft equipped with ACAS shall be identical to those applicable to non-ACAS equipped aircraft” (ICAO PANS-ATM, Doc 4444, para 15.7.3.1).

All quotes taken from EUROCONTROL - ACAS II Equipage Requirements (http://www.eurocontrol.int/msa/public/standard_page/ACAS_Equipage_Requirements.html)

However, and that is probably what you mean, TCAS is a mandatory equipment in the ECAC airspace. It can be inoperative though for up to 10 days at a time (if you do not enter german airspace).

[Nightrider]

Werll denti, exactly what you copied....the MEL may be more restrictive. And that is in some places the case.

Otto, did not find the engines in the MEL :E so, difficult to judge about their requirements...:}

[poldek77]

Nightrider - probably you will not be able for RVSM as your drift-down altitude may be below FL290 ;)

[Denti]

Of course, an operator may allways choose to be more restrictive. However it is not a requirement in any ECAC country as those have to be filed with eurocontrol and would be exactly on the site i cited. The only country that is more restrictive in general is germany, all others allow RVSM up to 10 consecutive days without TCAS. Of course, operators may be more restrictive and some are for good reasons.

[muduckace]

However, aircraft need to have a TCAS system these days and this makes it difficult. It goes down to ATA 34-40 and some CAA have superseded the MMEL of some manufacturers to have the AOC MEL showing that RVSM compliance is only given if an operational TCAS system is available.

I think you are slightly confused her as to what the MMEL of a specific aircraft is. It is an agreement between a cival authority and the manufacturer.

JAA | Master Minimum Equipment List - MMEL (http://www.jaa.nl/operations/secured/mmel/mmels.html)

Here is a great reference to current MMEL's, it will show how vague they are written. A carrier requires a MEL to be written and approved by a civial aviation authority to be in compliance with their ops spec for a given fleet. A carrier can decide to add RVSM notes to an MEL but do not need to even in required components for RVSM if the authority decides the carrier has covered the requirement through other means.

RVSM is maintained to IACO standards, the global aviation authorities establish these requirements so that they are the same (as close as possible) internationally.

TCAS in my oppinion has nothing to do with RVSM. Altitude maintaince is the main focus.

[Nightrider]

muduckace,
A carrier can decide to add RVSM notes to an MEL but do not need to
that is not true. Check the RVSM requirements on the Eurocontrol website and you will find out that operators have to establish a reference to RVSM equipment and their availability in their MEL.
The operators I worked for, as a contractor you may see more than one in a few years, have all this reference included, as I mentioned earlier.
And this is a wise decision as it reduces our search and read time for particular items.
There was even one operator where this reference was incorporated in the OM-B with the preambel that the MEL is part of the OM-B and thus references for RVSM, PRNAV etc can be found there.:confused:

poldek77

you are very much on the right track, even with the unbelieveable high ECON setting we have to use, at 68,000 kgs the 734 does not like a much higher level with two engines on the initial cruise section... :rolleyes:

[muduckace]

Clearly as MMEL's are written they give no respect to RVSM/CAT/ETOPS.. ETC. requirements. The governing civil aviation authority that is responsible for the MEL a carrier is responsible to abide by will clearly dictate systems that are required for operational functions such as RVSM... Period.

The manufaturers do though cater to the obvious needs of the above mentioned producing aircraft that are capable out of the box to comply with modern operating requirements.

As of now, besides your oppinion, I know of no authority that requires TCAS for RVSM operation.

Having said that most RVSM airspace is occupied by aircraft that have mode S transponders, it is for the most part a non issue.

Do not take my text out of content.

[Denti]

The reference to RVSM doesn't have to be in a special part but only at the singular system. It might be deemed easier though to put it all together in one extra part, however that is something each operator has to decide on its own. The last two i worked with didn't do that, they just had a note at the relevant system in the MEL that you might be able to operate but only outside RVSM airspace, same as for other systems (de-icing equipment for example, you can operate without it but are not allowed to enter icing conditions). However TCAS is not one of them, it is not required for RVSM, but if you have TCAS II you need a certain version.