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Crew ignored TCAS RA

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Crew ignored TCAS RA

Old 8th Nov 2016, 22:38
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Wonder what happens when the aircraft is intercepted by a fighter jet!
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Old 8th Nov 2016, 22:47
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It's been done and confused the target rather thoroughly. Tactical guys are briefed on potential TCAS confusion and have procedures to avoid it.
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Old 8th Nov 2016, 22:49
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The interceptor would switch off the Mode C/Mode S as they (visually) approach the target aircraft so as not to activate TCAS in either.

A problem with ignoring any RA on the basis of being "visual with the traffic" is where military traffic has caused the RA. There may well be two, (or more), and the one you can't see may be the real issue.
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Old 8th Nov 2016, 22:56
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Dear god please tell me the people advocating ignoring a TCAS RA are not professional pilots.

I'll put this in simple words. Never ever fail to follow a TCAS RA. I don't want to share the sky with you if you don't understand this. Even if you "think" you are visual with the conflicting traffic.

If you need evidence, read the Uberlingen accident report.

TCAS is the last, the final barrier between you and a mid air. If you receive an RA, EVERY OTHER DEFENCE AGAINST A MID AIR COLLISION HAS FAILED and you are in the last chance saloon.
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Old 8th Nov 2016, 23:04
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Reading of "pilots" ignoring RA frightens me.

It's not only foolish, but also dangerous. You either haven't read your manuals, or you did not understand them.
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Old 8th Nov 2016, 23:54
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Wasn't there an accident with a Russian airliner and a DHL cargo plane because the Russians obeyed the controller instead of the TCAS ?
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Old 8th Nov 2016, 23:56
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Uberlingen...

Yep, Uberlingen. Tragic for so many reasons, including the final act upon the controller.

https://en.wikipedia.org/wiki/Überli...-air_collision
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Old 9th Nov 2016, 02:54
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Recalling the Uberlingen tragedy, years ago I attended an IFATCA conference where the subject of a seminar was an analysis of the Uberlingen mid-air collision. Using the Swiss Cheese (pun not intended) model of causation, my group's task was to determine the single incident that ultimately led up to the fatal collision. Several sessions involving hundreds controllers concluded the usual and predictable causes. Nothing really new was uncovered, but it was an informative exercise nonetheless. However my self and a Scottish controller were singled out as having the most correct and simultaneously useless answer to the question.

We both concluded that if the driver of the bus carrying the UNESCO committee passengers had NOT gotten lost enroute to the airport, the mid-air collision would not have occurred.

The answer was very correct, and very useless. Absolute truth is not always of absolute value.

P.S. No "millennials" were in authority at the time of the Uberlingen tragedy. When anyone singles out millennials or baby boomers or old folks or the younger generation, my eyes roll up so far into my head, enabling me to see old episodes of Heartbeat.

Last edited by evansb; 9th Nov 2016 at 03:04. Reason: up in to my head
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Old 9th Nov 2016, 03:12
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whereas the elevation element is very accurate - azimuth not so. The relative bearing of the threat can be up to 30 degrees out leading to a high likelihood of misidentification.

That's why you follow RAs.
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Old 9th Nov 2016, 04:02
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and the GOL mid air collision? GOL turned off their transponder...and flew at a different level.

On September 29, 2006, GOL Airlines Flight 1907 flying at 37,000 feet collided in midair with an Embraer Legacy business jet over the Amazon jungle in Brazil. The badly-damaged business jet landed safely at a remote military base, but the GOL Airlines 737 was damaged too severely and crashed, tragically claiming the lives of the 154 passengers and crew aboard that flight. In the immediate aftermath of that tragedy, Brazilian authorities initiated criminal investigations and prosecuted the pilots of the business jet and the air traffic controllers. The actions by those authorities stand as the most noteworthy example of government criminalization of an aviation accident and caused many in the aviation industry to re-evaluate and refine their post-accident response procedures.

whereas the elevation element is very accurate - azimuth not so. The relative bearing of the threat can be up to 30 degrees out leading to a high likelihood of misidentification.

That's why you follow RAs.
Concur, due to the latency in both aircraft reporting systems, it seems best to follow the RA as it wants to always point you away from the perceived threat. tactically, we wont even go into the spoofing available with ADSB.
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Old 9th Nov 2016, 04:23
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Originally Posted by Golfbanajam
While not wishing to belittle the danger of ignoring it, surely an advisory is just that, it's advice ie "guidance or recommendations offered with regard to prudent action". If, having received "the advice" you MUST take action, then surely it's no longer advice?
This forum is for professional pilots.

Originally Posted by Underfire
tactically, we wont even go into the spoofing available with ADSB.
Try to stay on-thread, please.
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Old 9th Nov 2016, 04:53
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Incidentally, a rather nasty TCAS incident is often quoted in my company, in which one a/c received a 'Climb' RA in response to a threat above it. (Both a/c were changing levels!) The crew of that same a/c saw fit, on the basis of visual acquisition, to 'manage' the demanded manoeuvre!

The very nasty 'reversal' of commands to both a/c, suggested this 'management' was unhelpful!

There are very, very, very few TCAS incidents in which a 'zero/zero' is predicted. This was one of them. Due entirely to 'managing' TCAS demands!

Frankly, I don't know why we even bother looking out the window after an RA. Just follow the commands. Tell ATC, and fill in the ASR after you land. Rather than hit the front pages of every newspaper on the planet!!!

Last edited by 4468; 9th Nov 2016 at 05:06.
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Old 9th Nov 2016, 05:56
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Originally Posted by Locked door View Post

I'll put this in simple words. Never ever fail to follow a TCAS RA. I don't want to share the sky with you if you don't understand this. Even if you "think" you are visual with the conflicting traffic.
...

TCAS is the last, the final barrier between you and a mid air. If you receive an RA, EVERY OTHER DEFENCE AGAINST A MID AIR COLLISION HAS FAILED and you are in the last chance saloon.
I agree with the basic sentiment, but never say "never".

I've had three TCAS RAs.

1. On descent into the circuit of an uncontrolled aerodrome with a relatively high rate of descent (~1500 fpm) we got a CLIMB RA triggered by an aircraft that was taking off. We were clearly going to pass behind it and level off at least 1000' above it. We followed the RA for all of the good reasons mentioned already in this thread.

2. At 200 feet on short final we received a DESCEND RA. Nope, not going to follow that one.

3. In the flare (same approach as number 2. above) again we received a DESCEND RA. Needless to say, we didn't follow that one either.

Number 2 and 3 were triggered by an aircraft on the ground with its transponder on and it turned out that our RADALT was sending bad info to our TCAS so the usual low level inhibits weren't active.

So yes, always follow the RA, except for when the system is obviously broken.
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Old 9th Nov 2016, 07:00
  #34 (permalink)  
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Incidentally, a rather nasty TCAS incident is often quoted in my company, in which one a/c received a 'Climb' RA in response to a threat above it. (Both a/c were changing levels!) The crew of that same a/c saw fit, on the basis of visual acquisition, to 'manage' the demanded manoeuvre!
Forgive me 4468, but I'm not following what happened.

By 'managed' you mean that they decide to ignore the RA and stayed level? And that led to a tighter conflict, near collision? Presumably that was because the other a/c was already descending and TCAS was telling it to descend assuming our protagonists were going to climb as directed?
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Old 9th Nov 2016, 07:24
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Your reaction to an RA will be an instinctive one, whether ignored or followed. For me to ignore an RA I would have to recognise that following the RA would be in some way unsafe. Aerocat gave a couple of examples where this was essentially the case. I would like to know how the Enter air crew felt that following their RA would be unsafe. It appears that the reality is not that they deemed it unsafe, but rather unnecessary and IMHO, this is not a good enough reason to ignore.

It doesn't help, however, that the most common cause of an RA is essentially 'unnecessary' with ATC minimum separation not comprimised(2 aircraft cleared to climb and descend respectively to levels/altitudes with 1000' separation, both aircraft using high ROC/ROD).
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Old 9th Nov 2016, 07:35
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It's been thrashed to death before: but why were you not squawking TA Only.
After a rapid decompression, pain, fogging etc, it is just possible that normal pilots would forget to initially select TA only prior to starting downhill. If only everyone were as good as you in these situations.
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Old 9th Nov 2016, 08:13
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Heard an interesting one on frequency a couple of weeks ago. A Qatar heavy descending over the Balkans to get out of moderate turbulence had an RA with an aircraft going the other way as he was levelling off. The pilots thought it was a system error, the controller suggested that it might be due to turbulence. Anyone else come across anything similar?
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Old 9th Nov 2016, 08:27
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Apart from not being sure that the aircraft you have in sight is the one creating the TCAS alert, the main reason is that airline pilots are lacking any sort of training for positioning and manoeuvring in relation with other aircraft.
Ex-mil pilots got that training : fighter pilots of course but also transport dudes (which doesn't mean that they would extract themselves every time from a complicated situation, in a TMA for example with multiple intruders) (although some real fighter pilots have been practising 2 vs 2, or 4 vs 4) not mentioning rejoining tankers with multiple fighters all around, or fly-by with dozens of aircraft....

So in the meantime, and in the absence of better training, fly the TCAS orders !
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Old 9th Nov 2016, 09:32
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The subject has nothing to do with mil training or how good you think you are, learn and follow the TCAS rules.
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Old 9th Nov 2016, 09:52
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Agreed. Even if we can spot another likely aircraft, how can we be sure it is the actual target of the RA?

Answer: We can't.

TCAS looks at all transponder equipped aircraft up to 80nm away including behind and to the sides of us and up to 9,900' above and below our own aircraft.

I might be able to spot aircraft in front of me, or a contrail, but I cannot see aircraft behind me, or to the side - behind the cockpit window field of view cut-off, or those directly above or below me. So it is very dangerous to assume that the one target one can see is the source of the RA.

An RA, incorrctly ignored on the basis of observation of an aircraft ahead might cause severe problems if the actual intruder was behind, directly above/below, or otherwise out of sight of one's own aircraft.

Don't even bother looking. Instead, if a TA is triggered; eyes inside onto the PFD and mentally review the actions and calls for an RA.

Last edited by Uplinker; 9th Nov 2016 at 10:03.
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