Fortunately most operating States (countries) are signatories to ICAO which includes agreed Rules of the Air. As such each state will promulgate local rules/laws/guidance that accord with ICAO. And hopefully not too much is lost in the translation.
Basically the Rules say that a pilot shall follow an RA
unless doing so would jeopardize the safety of the aeroplane.
A review of the ICAO Rules of the Air covering TCAS (ACAS) from
http://www.eurocontrol.int/acas/Oper...rocedures.html are as follows:
3.2 Use of ACAS indications
The indications generated by ACAS shall be used by pilots in conformity with the following safety considerations:
a) pilots shall not manoeuvre their aircraft in response to traffic advisories (TAs) only;
Note 1.— TAs are intended to alert the pilot to the possibility of a resolution advisory (RA), to enhance situational awareness, and to assist in visual acquisition of conflicting traffic. However, visually acquired traffic may not be the same traffic causing a TA. Visual perception of an encounter may be misleading, particularly at night.
Note 2.— The above restrictions in the use of TAs is due to the limited bearing accuracy and to the difficulty in interpreting altitude rate from displayed traffic information.
b) on receipt of a TA, pilots shall use all available information to prepare for appropriate action if an RA occurs;
c) in the event of an RA, pilots shall:
1) respond immediately by following the RA as indicated, unless doing so would jeopardize the safety of the aeroplane;
Note 1. — Stall warning, windshear, and Ground Proximity Warning Systems alerts have precedence over ACAS.
Note 2. — Visually acquired traffic may not be the same traffic causing an RA. Visual perception of an encounter may be misleading, particularly at night.
2) follow the RA even if there is a conflict between the RA and an air traffic control (ATC) instruction to manoeuvre;
3) not manoeuvre in the opposite sense to an RA.
Note. – In the case of an ACAS-ACAS coordinated encounter, the RAs complement each other in order to reduce the potential for collision. Manoeuvres, or lack of manoeuvres, that result in vertical rates opposite to the sense of an RA could result in a collision with the threat aircraft.
4) as soon as possible, as permitted by flight crew workload, notify the appropriate ATC unit of the RA including the direction of any deviation from the current air traffic instruction or clearance;
Note. — Unless informed by the pilot, ATC does not know when ACAS issues RAs. It is possible for ATC to issue instructions that are unknowingly contrary to ACAS RA indications. Therefore, it is essential that ATC be notified when an ATC instruction is not being followed because it conflicts with an RA.
5) promptly comply with any modified RAs;
6) limit the alterations of the flight path to the minimum extent necessary to comply with the resolution advisories;
7) promptly return to the terms of the ATC instruction or clearance when the conflict is resolved; and
8) notify ATC when returning to the current clearance.
Note.— Procedures in regard to ACAS-equipped aircraft and the phraseology to be used for the notification of manoeuvres in response to a resolution advisory are contained in the PANS-ATM (Doc 4444), Chapters 15 and 12 respectively.