Tcas? Priority over ATC instructions?

[sabenaboy]

The recent collision over Lake Constance in Germany, has demonstrated that it is vital that pilots obey TCAS Advisories even if ATC tells them to do exactly the opposite.

I have been trained to always obey the TCAS. However I am not able to find an official document published by ICAO or JAA, that stipulates that TCAS does indeed always takes precedence over ATC instructions.

Could someone please tell me where exactly this is written down. A link to an official document would be highly appreciated!

Thanks,
Sabenboy.

[Crash & Burn]

Have a look at this previous thread here (http://www.pprune.org/forums/showthread.php?s=&threadid=61159)

There are a few responses regarding the legality of it all but it seems to depend on which country you are in as to whether it's a legal requirement or not.

[sabenaboy]

Thanks for your reply, but that thread doesn't give the answers I'm looking for.
I am looking for an official publication from JAA or ICAO which states that RA should be obeyed over ATC instructions.

Somebody please give me a reference or a link to such a document.

Best regards,
Sabenaboy.

[sabenaboy]

Eureka, I found it:

http://www.eurocontrol.int/acas/webdocs/ACASstateletter%20v17_27Jul2002.doc

quote: "Your attention is specifically invited to paragraph 3.2.3b), item 12), which states: “if pilots simultaneously receive instructions to manoeuvre from ATC and an RA which are in conflict, the pilot should follow the RA”. The reason for this statement is that ATC may not be aware of ACAS RAs, and may therefore issue instructions that are contrary to an ACAS RA."

[NorthernSky]

Sorry, sabenaboy, that which you quote is not legislation.

The Tokyo Convention is very plain, and explains that if the pilot-in-command deviates from an ATC clearance, he assumes responsibility for the safe conduct of the flight.

That's the law.

From where I sit, the Tu154 crew were right, the B757 crew were not, WITH SPECIFIC REGARD TO EXTANT INTERNATIONAL LEGISLATION. With regard to airmanship, the B757 PiC was right. This is my opinion only.

//Start of rant//

ICAO are responsible for some apallingly bad rule-making and 'standardisation'. If we all stop work on safety for a month and simply address ICAO's failings, we have an opportunity for great good. Until we all do, we'll simply be p***ing in the wind for safety.

//end of rant//

[BEagle]

-50 Sec: Tu-154 TCAS: "Traffic, traffic".

-45 Sec: Zurich-south: "VTS29E ... Descend, flight level 350, expedite, traffic." (Controller to the Tu-154, call sign VTS29E. Dots designate unintelligible words or parts of phrases.)

-40 Sec: Tu-154 cockpit area mike: "Begin descent." (It is most probable that this phrase in Russian belongs to the Tu-154 commander.)

-38 Sec: Boeing TCAS: "Descend, descend!"

-35 Sec: Tu-154 TCAS: "Climb, climb!"

-34 Sec: Tu-154 cockpit area mike: "Climb!, it says" (One of the crew members Tu-154, most likely the First Officer, repeats the TCAS alert.)

-32 Sec: Tu-154 cockpit area mike: "Descend, b..." (This is said with confidence, implying that ATC instructions are of greater importance than TCAS alerts.)

-30 Sec: Zurich-south: "VTS29E, descend to flight level 350, expedite descent."

-25 Sec: Tu-154 "VTS29E expediting to flight level 350, VTS29E."

-20 Sec: Zurich-south: "Yes, you have traffic, two o'clock, now at 360. (In reality the Boeing was at 10 o'clock)

-19 Sec: Boeing: Sound of audible indicator.

-13.3 Sec: Boeing: "611, TCAS-descent"

-11 Sec: Tu-154 cockpit area mike: "B... d', where is it?”

-9.5 Sec: Tu-154 TCAS: "Increase climb!, increase climb!"

-5.3 Sec: Tu-154 cockpit area mike: "Climb!, it says" (The same member of the crew who first drew the attention of the Captain to the indication of the TCAS again brings it to his attention.)

-3.8 Sec: Boeing cockpit area mike: <Expletive>

-1.8 Sec: Tu-154 cockpit area mike: <Expletive>

0 Sec: Collision

[Nick Figaretto]

Sh!t... :(

[Capt Claret]

sabenaboy

I'm not aware of any legislation as such, however, Australian AIP, Jeppesen, ATC, page AU917, para 7.2 : (pilot phraseology in BOLD)

when unable to comply with a clearance because of a TCAS resolution advisory UNABLE TO COMPLY, TCAS RESOLUTION ADVISORY

[sprucegoose]

My question is, and I kind of know the answer, is whether the predictive capability of TCAS is better than the predictive capability of ATC radar. Obviously it is which is why I wonder why any organisation would install TCAS and then tell its pilots to ignor it in the face of contrary ATC instructions.