tcas alert from a plane without alt ind.
 

Hi,

I have a question if you can help me


What should we do if we have a TCAS traffic alert of a small plane without mode S so no altitude information. What do you do?

personally i avoid the traffic (flying ifr o vfr) and i notify atc.



thank you

No RA, so no "climb climb" for example

no TA, so no "traffic traffic"

Personally, I would increase my visual vigilance, but not modify my flight path nor notify atc

Well it happen to me, i had a traffic alert because it was nearest than 5 nm and i was IFR under radar control service.

Orichetti,

you received an amber tcas traffic alert on a target with no altitude displayed?

I didn't think that was possible, perhaps I'm mistaken then

yes that´s right, it appears in yellow saying how many miles is from you "2.3 nm" but no altitude indication, so it should be normally below (in other airspace) but i was trying to find somewhere if i should deviate from the horizontal navigation.


between a "mode a" and a "full tcas" equipment there is a TA nothing else of course.


but i am still on doubt of the correct procedure. thanks for your answers

You get a TA alert on a non altitude reporting target because the system ASSUMES the target is at your altitude and responds by warning you of its presence. The system doesn't KNOW what altitude the target is really at though so it can't give an RA.

If I got one I'd have a look around and put the lights on and hope I don't hit anything. A lot of the time it is caused by low level VFR traffic that are no real conflict and that you will never see.

My FCOM says quite clearly as a warning "DO NOT MANOEUVRE ON A TA ALONE!". If you visually acquire the traffic and it is obviously in conflict, then fine, get out of the way, but to manoeuvre horizontally around a target based on the TCAS display is fraught with danger because the TCAS display does not accurately present bearing information.

I have been retired 10 years, but previous to that when operating in and out of London Heathrow these nuisance warnings were common and infuriating.

They were normally were caused by VFR traffic low down, but it is alarming to get an orange blip and an aural warning that you might be about to hit something.

Traffic with transponders should be forced to have altitude reporting, or be kept out of the airspace.

This is something that those of us who have to have to operate mainly in Class G deal with on almost a daily basis.

It is a worry, tbh and all you can do in practical terms (especially when not in receipt of an ATC radar service), is to look out even more. :uhoh:

it usually happens to me on take off from oxford sometimes on IMC SID and the " hope I don't hit anything" does not calm me. normally i ask for a hdg to avoid the target..never said nothing to me from atc, just report when clear. thanks for answers guys. good landings.

What if the heading you request takes you into the target? If you watch the presentation of targets on a TCAS you will see all sorts of weird stuff, the point being that TCAS bearing information is highly unreliable.

TA no alt?

Fine, start looking, turn on your lights and the traffic is either above you, at the same altitude as you, or below you. Guess where you should look first!

You can ask ATC, DO YOU SHOW TRAFFIC MY 1 o'clock, no altitude?

It is possible ATC is working the traffic and had the altitude reported verbally and advised traffic to report leaving or any altitude changes.

yes i always ask atc and they usually say traffic might below but no altitude displayed

By the way, you don't need the conflicting aircraft to have mode S to get an RA, mode A/C will do.
Often happens with Gatwick departures on some SIDs which pass directly over Redhill. If traffic in the Redhill circuit only has mode A you will get a TA.