TCAS Flashcards
TCAS
Traffic Collision Avoidance System
TCAS regulations
The Airborne Collision Avoidance System II (ACAS II) was introduced in order to reduce the risk of mid-air collisions or near mid-air collisions between aircraft. It serves as a last-resort safety net irrespective of any separation standards.
ACAS II is an aircraft system based on Secondary Surveillance Radar (SSR) transponder signals. ACAS II interrogates the Mode C and Mode S transponders of nearby aircraft (‘intruders’) and from the replies tracks their altitude and range and issues alerts to the pilots, as appropriate. Non-transponding aircraft are not detected.
ACAS II works independently of the aircraft navigation, flight management systems, and Air Traffic Control (ATC) ground systems. While assessing threats it does not take into account the ATC clearance, pilot’s intentions or autopilot inputs.
Currently, the only commercially available implementations of ICAO standard for ACAS II (Airborne Collision Avoidance System) are TCAS II versions 7.0 and version 7.1 (Traffic alert and Collision Avoidance System). ICAO Annex 10 states that new ACAS installation after 1 January 2014 must be version 7.1 compliant and the existing units must be upgraded to version 7.1 before 1 January 2017.
Types of TCAS
- ACAS I Gives Traffic Advisories (TAs) but does not recommend any manoeuvres. The only implementation of the ACAS I concept is TCAS I.
- ACAS II Gives Traffic Advisories (TAs) and Resolution Advisories (RAs) in the vertical sense (direction).
- ACAS III Gives TAs and RAs in vertical and/or horizontal directions. Also referred to as TCAS III and TCAS IV. Not currently implemented and unlikely to be in the near future.
TA (traffic advisory) may become RA (resolution advisory) in … seconds
15
TA … until CPA
20 - 48
RA … until CPA
20 - 35
In case of RA, the pilot must react in … seconds
5
In case of RA:
- disconnect AP
- DO NOT follow the FD bars
- DO NOT change the altitude set on the AFCS
RA in approach …
CLIMB and execute a GO AROUND
In case of TCAS RA, does the ATC have any responsibility ?
!!! NO, all maneuvers must be executed in concordance with the actions displayed by the instrument !!!
OPEN DIAMOND
Shows other traffic. Range and bearing of other aircraft within surveillance range and selected range and altitude for display.
SOLID DIAMOND
Traffic within ± 1200 ft and 6 NM of own aircraft.
SOLID CIRCLE
Intruder. TA generated. Range and bearing relative to own aircraft.
SOLID CUBE
Traffic generates conflict. RA generated range and bearing relative to own aircraft.
TRAFFIC ARROW
(same color as associated traffic symbol): climb or descent rate (>500 ft/min) of intruder aircraft
