ICAO Doc. 8168, Vol. 1, Chapter 3.2:
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, wind shear, and ground proximity warning system 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 intruder aircraft.