View Full Version : TCAS-I vs TCAS-II
aseanaero
17th Feb 2009, 10:32
What's the difference between TCAS-I and TCAS-II and what limitations does having only TCAS-I impose ?
see Traffic Collision Avoidance System - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/TCAS)
Collision Resolution Advisories are coordinated by TCAS II between platforms before vocalised instructions are issued to pilots.
II is the one to have.
aseanaero
17th Feb 2009, 11:07
I was speaking with a technical manager of one of the local charter companies and he said if they had TCAS-II on board they could operate some of their business jets above 45,000 ft ? With TCAS-I he was saying it was 35,000ft limitation. Is this correct ?
maverick2872
14th Mar 2009, 12:29
tcasII uses mode S transponders to give u RA's, ie an escape maneuver in the vertical plane, however if the other aircraft has mode C transponder you will not be getting any RA's, instead you get TA's ie traffic advisories, in TCAS I u can only get TA's
Denti
14th Mar 2009, 13:18
That is wrong. Of course you wll get RAs against Mode C equipped aircrafts as long as they report their altitude. It just won't be coordinated as that not only needs Mode S but another TCAS II as well.
You won't get RAs against aircrafts which do not report their altitude though, simply because TCAS doesn't know in which altitude said aircraft ist. TAs are still generated to improve crew awareness.
aseanaero
14th Mar 2009, 14:01
Thanks everyone for the replies
maverick2872
16th Mar 2009, 20:32
im sorry denti is correct,, looks like GSP is misleading
Nigd3
16th Mar 2009, 20:45
Has anyone any info on TCAS IV?
I read it also had lateral RAs but haven't seen a detailed spec yet.
and I still don't know what happened to TCAS III :confused:
Denti
16th Mar 2009, 21:07
Taken from the Eurocontrol ACAS FAQ (http://www.eurocontrol.int/msa/public/faq/ACAS_FAQ.html):
What is the status of the development of ACAS that will issue both horizontal and vertical Resolution Advisories?
ACAS III - Airborne Collision Avoidance System that issues RAs in vertical and/or horizontal directions is also referred to as TCAS III and TCAS IV. It has not been implemented and it is unlikely to be in the near future. ICAO SARPs for ACAS III have not been developed. Currently, there are no plans to proceed with such a development.
Piper19
18th Mar 2009, 01:17
TCAS I = warnings when collision situation arises
TCAS II = same with computer that calculates best escape path vertically (in cooperation with Mode S to talk to other a/c TCAS computer). Escape path displayed in cockpit + voice
TCAS III = same, but also horizontal escape paths. Most new computers have this ready to be implemented, but not activated. But e.g. tot test a modern TCAS processor, you have to align IRS's, this is to test the horizontal system, even if it is not installed yet. I don't know how far regulations are at TCAS III.