Discussion in 'Pilot-Controller Questions' started by NovemberEcho, Apr 10, 2017.
mmm that mode C accuracy tho'
Anyway, the RA's getting complied with.
Never know if it's Joe Blow and a flight of 4 RVs stacked up and only one squawking, visual separation with the perceived target just isn't enough of a guarantee
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MiG-28s! Nobody's ever been this close before!
I believe SFO is the only place we can turn TA/RA off if we're doing the visuals there. On vacation so I'm not gonna go look in the book.
That is the same guidance we have as well. We can use TA only when operating on the paired approach there.
Also, it (should) go to TA only automatically at 1500 feet (I think?). Although apparently we had a crew get an RA at 400 feet the other day.
It sounds like there was an error somewhere, either pilot or equipment. If your getting an RA to 6800, either the other aircraft is actually at 5800 or there is an error, because the transponder is reporting 5800.
As far as the other traffic, most likely it was in a position that would not conflict with the RA in the TCAS evaluation.
We are required to comply with any RA. Regardless of communication or visual contact. There have been too many miss judgements of visual contact that the electronic guidance takes priority these days.
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@NovemberEcho , this accident is the basis of why we're taught to always, always, always obey the TCAS RA no matter what:
I realize that you probably have a bigger, better picture in the TRACON, but I still think it's safer overall to always follow the RA.
For the operators going into SEA is there any guidance with traffic going into BFI? I've seen some interesting departures from the flight path with convergence there.
I'm a little surprised so many of you have SOP's that mandate following a RA even with the traffic in sight. Ours says we have to comply unless the traffic is in sight and we can maintain visual separation. How do you guys do operations into SFO, DEN, SEA, etc if you're required to comply regardless of the situation?
I believe SOP is to turn off the alert (?)portion of TCAS at select airports.
We have closely spaced parallels and pairing to them as traffic volume decreased became less frequent. Suddenly we had a huge spike in RAs associated with one airline. After a month or two of WTF moments when finally got word that said airline now leaves their TCAS on alert (?) while in our terminal area.
Our guidance for having traffic in sight only applies to TAs. RAs must be complied with. We've had a few loss of separation events because guys thought they had the intruder in sight and didn't follow he RA and they were looking at the wrong traffic.
I used to get RA's every other time I flew in to DEN. If we had to react to every one DEN's capacity would be cut by 2/3rds. I remember one extreme case on a visual when I undershot the 16L localizer by a few degrees and kept maybe a 2-3 intercept angle in. Our RA was going off constantly for like 30-40 seconds until we and the traffic on 16R finally got fully lined up.
"Traffic is in sight, no factor."
"Traffic is in sight."
CLIMB CLIMB NOW
"Traffic's still in sight"
DESCEND DESCEND NOW
"Wait, now it switched?"
DESCEND DESCEND NOW
CLIMB CLIMB NOW
CLIMB CLIMB NOW
CA: "Are you trying to set that thing off?"
CLEAR OF CONFLICT
"Yeah, he's still right there."
I dunno, I just feel like you're inviting trouble by selectively turning it on and off. One slip of the memory and you've got yourself a mid-air that could have been avoided.
We had a TCAS briefing a few months ago. Only thing I remember is that if the system sees only a 600 foot difference (not sure if that's predicted to be 600 feet in a certain time, or is at 600 feet right now) TCAS will set off an RA.
Didn't make much sense since ATC is set up to run 500 foot separation.
Close, but it was earlier than that.
Also, @NovemberEcho, when I refuse to call traffic in sight, that picture right there is why. If I'm not 100% positive I'm looking at the right aircraft, and if I'm not 100% positive I can keep him in sight, I'm not going to call traffic.
Yeah that much I figured. I don't want you calling them in sight if you're not sure it's the right one either. I had an incident at KECP where the RJ called a T-6 in sight but it was actually the PC-12 in front of the T-6 and when I told him to follow cut the T-6 off.
The PSA accident was what spawned the requirement for TCAS. In the Uberlingen collision, both aircraft had TCAS, but one followed the RA and the other followed ATC, resulting in a collision. The Uberlingen collision has been used in multiple CRM classes to stress the reason that we are required to comply with an RA even if we think we have an aircraft in sight.
To clarify, yes after the Uberlingen collision there was a requirement to follow TCAS over an ATC instruction for traffic avoidance. The sad thing is ICAO had a heads up on this issue in 2001 when two JAL widebodies had the same situation and nearly collided. One aircraft followed TCAS, other followed ATC. It was only when one plane acquired the other visually and took dramatic evasive action to avoid the other, injuring passengers in the process.
Sadly, ICAO didn't respond in time and the July 1, 2002 Uberlingen collision happened.
As for PSA 182, it was a terrible accident, but it still wasn't the one that broke the camel's back for TCAS. That came later in 1986 as a result of Aeromexico 498 midair with a Piper Archer. After this Cerritos midair disaster (on approach to 25L at LAX), TCAS was finally mandated.
Does TCAS work with non-transponder/non-mode c equipped aircraft? iirc the ATC didn't notice the Cherokee because it was a primary target only.
No. TCAS requires a transponder to function.
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