PPRuNe Forums - TCAS 2 on 744

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Does the TCAS 2 system on the 744 show all aircraft within 40 miles +/- 2500ft, or does it automatically suppress the display of aircraft traffic that is not immediately in conflict with the airplane?

Cheers

BWB

BWB,

I can't remember the extents of TCAS 2's coverage volume off the top of my head, but no it doesn't suppress targets not considered a threat (ie. it displays all targets within its coverage volume).

IORRA

Quote:

it doesn't suppress targets not considered a threat

It may do.

TCAS has something called 'interference limiting mode' which becomes active when the total ammount of SSR transmissions are such that the frequencies are becoming congested.

Once this happens, TCAS will drop from "full time" tracking more distant contacts and/or those with range opening. Full time tracking is about one update per second, this can be dropped to as rarely as once per 10 seconds.

Only traffic in 'full time' tracking is shown on the traffic display.

Source: Rockwell Collins Advisory Leaflet - Common Causes For TCAS Traffic Dissapearance.

CPB