Tcas Compliance (global)

[Established ILS 27L]

Your thoughts & opinions please......

[moleslayer]

Not sure what it is you're after27L

[followme]

If a pilot gets an RA and takes action I, as a controller, want to know exactly what action is being taken. If the RA is correct I will advice position of traffic, if spurious I will assure nothing showing on radar...communication is the key...

[Lieutenant Dan]

Had a foreign RJ100 the other day, passing FL175ish in CAS, reported a TA against an aircraft with no height info. Only traffic was a 7000 squawk with no Mode C.

Does anyone know what the vertical limits for TCAS coverage are?

[West Coast]

In the past two acft I have flown, it is a variable envelope.
When in the above mode (for climb) it is 8700ft above to 2700ft below. In level flight its 2700ft above and below. For descent its placed in below mode, then its 8700ft below to 2700 above.

[moleslayer]

Envelope limits for my type same as West Coast.
For RA's ....react IMMEDIATELY
As long as no delay, not more than 1500fpm vertical speed should be req'd.
Advise ATC soonest.

[gjp]

Thought I would post here as I am hoping for a profesional opinion. I am concerned about RVSM and TCAS.
It is my understanding that TCAS is not a requirement for RVSM ops however it is a requirement for Euro airspace. You can get dispensation to operate - limited time - in Euro airspace without TCAS.

[Capt Pit Bull]

West Coast.

I think you may be confusing the 'Display Volume' with the 'Surveillance Volume'.

Surveillance Volume:

The range that TCAS can track other aircraft. In range terms this is variable and depends on transmission power (which in turn is affected by traffic density), but is usually around 40 NM. In altitude terms is is only limited by the maximum / minimum limits of the encoding in Altitude Reporting - something like -1,000' absolute to +100,000' or more. For a precise limit, ask and avionic expert, but effectively unlimited.


Display volume:

The volume that is shown on your traffic display, which typically +2700' to -2,700' relative, extendable in either direction up to around 8,000' to 9900' (type dependant), out to whatever range is selected on the traffic display / EHSI. Range settings anywhere between 6 NM and 40NM are common.

The display volume only determines whether or not 'Other Traffic' blips (usually open diamonds) are shown.

All other categories of blip, be they Proximate, TA or RA are always shown ,regardless of Display Volume selection.

i.e. TCAS tracking and collison avoidance assessment is not affected, in any way, by the display volume settings.

If a TA or RA is in progress, but outside your vertical settings, it appears anyway (note - proximate traffic criteris means they are always within relative altitude range).

If a TA, RA or Proximate is in progress, but outside the range, it appears as a half blip at the edge of the display.


Lt Dan,

Against non altitude reporters, TCAS assumes the worst and that all vertical triggers are met. Hence a TA is generated. Obviously, since there is no vertical data, an RA can not be issued.

The associated blip is still shown, albeit minus altitude tag, to allow the crew to see what direction to look in.

To be honest, Non altitude TAs are quite common. I'm surprised the crew mentioned it.

Some TCAS types have an inhibition of non altitude TAs at high altitude. Rationale is: non altitude = high probability GA traffic below CAS, therefore ignore. Typically cuts in at the high teens of thousands of feet.


Hope thats of some use.

CPB

[West Coast]

Capt Pit bull
Excellent post, thanks

[Crotalus]

In cat D airspace do pilots find it useful or a pain to be advised of non mode c equipped but transponding aircraft (generally vfr and usually known and NON conflicting).I ask because a lot of traffic in and around the TMA I work in does not have an altitude reporting facility and I always personally took the view that if I knew about it I would (time and other tasks permitting) rather advise the aircrew rather than they ask.Regards