Tcas turn

[BeerFly]

Will my Tcas give me an alert or resolution when my projected flight path is towards another aircraft projected flight path.
Meaning it will give me lateral Resolution.

Is this maybe a new generation Tcas ?

And also will a Tcas send me into a mountain when combined with
EGPWS ?

Cheerio

[quid]

I don't know your equipment, so I'm not going to try to guess. Not being a smart a**, but doesn't your training department teach this stuff? They should have the answers.

[BeerFly]

Hey quid, this forum is also to ask answers on items where you like to know more about instead of going trough the tech-division stuff. Well current equipment is not able.

[Shore Guy]

TCAS/ACAS in its present configuration will not give any lateral commands to avoid a collision. The current TCAS technology is not very good at determining azimuth information – it may be up to 30 degrees off.

The latest version of TCAS/ACAS (version 7.0) does incorporate some improved software to reduce the number of RA’s due to close lateral encounters. Horizontal miss distance filter (HMDF)--new logic included with Version 7 will, whenever possible, suppress an RA when adequate horizontal separation between aircraft exists during potential encounters. Currently, when two non-maneuvering aircraft are approaching each other at the same altitude and offset flight paths, an RA may result if the aircraft pass as close as approximately 3 miles. In the same scenario with Version 7, an RA may not result unless the two aircraft are closer than approximately 1.5 miles. (Note: The approximate distances cited above are only an example. The actual lateral separation between aircraft will vary with altitude and depends upon many other factors, including closure rate between the two aircraft.) Simulations and testing have shown that the HMDF will reduce the number of RAs by approximately 25 percent in U.S. airspace, and up to 40 percent in European airspace, further minimizing RAs that cause disruptions to ATC as well as reducing the number of RAs that flight crews and controllers view as unnecessary.

There has been research into TCAS III, but for the present time, this effort has been abandoned. TCAS III was to have incorporated lateral resolution commands, but was found to be incapable of doing so with existing technology of (directional) antennas and processors, and with the small existing time frame that TCAS operates on – lateral commands would require a greater “look ahead” capability.

Future versions of collision avoidance systems are anticipated to require GPS/ADSB and data link (Read: Mode S) capability. They will incorporate both vertical and lateral separation capability. Current ADSB technology requires interaction with Mode S transponders to function properly as a full fledged collision avoidance system (if will not work properly with Mode C only). There is no current or anticipated regulatory requirement to equip all aircraft with Mode S transponders. Nor is there an approved ADSB based anti-collision system certified. Full operational implementation of any of these (proposed) systems is many years away.


No, to my knowledge TCAS/ACAS does not interact with GPWS/EGPWS to have an RA maneuver not conflict with terrain. They are stand alone products.

Hope this helps.

[SimJock]

..and finally, GPWS is always wired so that its aural warnings overide those from TCAS, TCAS aurals are in effect 'inhibited' whilst GPWS is doing its bit, but you will still see the traffic data and RA's on whatever TCAS display equipment you are using.

[West Coast]

For us, a EGPWS aural of "terrain terrain" is controlling and overrides any TCAS commands for descent. Not uncommon to see this in the box.

[wingtip777]

hi Shore G, your gave a very good information to me. but where did you get those information? thanks!

[Shore Guy]

Wingtip and all,

I just wrote a piece for our in house publication on the German midair - my response was from info in the article and notes. Main sources were manufacturers, FAA and Eurocontrol documents, and some other articles on TCAS.

[BeerFly]

Good info; thanks !

Ho ho ho