TA/RA

[pilotho]

after long study i have finally found out what TA/RA stands for, although i have still got a question.

why is there an option to only have TA or RA respectivly when surely TA/RA should be selected all the time.

[janpieter]

The NON NORMAL 737 Checklist ask for TA for 1 Engine INOP flight
TRANSPONDER MODE SELECTOR . . . . . . . . . . . . . .TA ONLY
[Prevents climb commands which can exceed single engine performance
capability.]

This should be one of the reasons I guess.

Regards

[5150]

Flying in formation or poling in visually to small airport with VFR/GA traffic.

[HotDog]

after long study i have finally found out what TA/RA stands for, although i have still got a question.
why is there an option to only have TA or RA respectivly when surely TA/RA should be selected all the time.

The only option I'm aware of is TA/RA or TA.

TA/RA is the normal operating mode and provides Traffic Advisories and Resolution Advisories.

TA provides Traffic Advisories only; no Resolution Advisories are issued. This mode prevents TCAS from issuing RAs when the aircraft is intentionally flying close to another aircraft such as closely spaced parallel approaches.

At Radio Altitudes less than 900 ft AGL descending or less than 1,200 ft AGL climbing, TCAS will be silent below these inhibit altitudes and is in TA ONLY mode. No RAs will be displayed, TAs will be displayed on the VSI/TRA but no "TRAFFIC - TRAFFIC" message will be heard. If an RA is active when the aircraft passes into the inhibited radio altitude, the RA (red square) will transition to a TA (amber circle) any red or green arcs displayed will be removed, no "CLEAR OF CONFLICT" message will be announced.

[janpieter]

Here is also a good summary concerning the TCAS mode control :

http://www.757.org.uk/767/systems/sys2.html

TCAS is normally operated in the TA/RA (TA and RA) mode. Sometimes it may be necessary to operate in the TA Only mode to prevent undesired RAs.

The TA Only mode is used during engine out operation to prevent RAs when inadequate thrust is available to follow the RA commands. Also, it may be used when intentionally operating near other aircraft that may cause RAs, such as during parallel approaches and VFR operations.

[punkalouver]

TA provides Traffic Advisories only; no Resolution Advisories are issued. This mode prevents TCAS from issuing RAs when the aircraft is intentionally flying close to another aircraft such as closely spaced parallel approaches.


I don't remember anything in the PRM or SOIA approach training videos stating that the TCAS should be in TA only for these approaches. Is this your company procedure?