Hey all, I was listening to live air traffic control, and I heard an aircraft say something similar to "Santa Ana tower, United 22, I almost had an RA". Can anyone tell me what that means?

Thanks!
Jimmy

(Conflict) Resolution Advisory. Refers to TCAS or other traffic-detection alerts.  Not sure how you "almost" have an RA, but maybe the pilot meant he had visual contact with traffic that appeared to be in conflict for some period of time.

beaky wrote on Jan 9^th, 2010 at 9:02pm:


TCAS will go through several stages before giving you and RA.

In the systems I've used, the first indication is the change of icon indicating the "threat" aircraft (in both aircraft the TCAS display has been integral to the VSI), then if it becomes more of an issue a warning of "TRAFFIC, TRAFFIC" (you can get these quite normally from and aircraft only 1000ft above of below you. or climbing/descending to a level below/above you, and hence rate of climb should be decreased when approaching the desired level, otherwise you can casue spruious RAs) and the finally, if the flight paths are increasing the chance of a collision, the RA, ordered by "CLIMB, CLIMB" or "DESCEND, DESCEND" command.

So you can "almost" have an RA, in a manner of speaking. Although it's rather down to the judgement of the person claiming to have almost had the RA...

beaky wrote on Jan 10^th, 2010 at 5:19pm:


It's the one that really gets your attention if you've managed to ignore the other two!

Thankfully I've only had one RA - thankfully we were in formation with to "threat" at the time, and had accidentally clicked the switch round a notch too far (you can select "TA" where you'll only get the "TRAFFIC" call, and no RAs - useful flying in formation, or "TA/RA" where you get the full series of alerts if necessary.

Clever bit of kit!