Crew ignored TCAS RA
 

Report: Enter B738 near Stuttgart on Feb 25th 2016, crew ignored TCAS RA

"the crew received a TCAS resolution advisory to climb indicating a conflict with a fast climbing Falcon 2000 business jet climbing out of Memmingen (Germany). The captain made visual contact with the conflicting aircraft, assessed there was no need to perform an avoidance maneouver and therefore did not follow the TCAS resolution advisory, the captain however reported the TCAS RA to ATC."

Is it common to ignore RAs? Was there margin to climb higher from FL370? What do you do if you cannot comply with RA because you're at your ceiling?

Someone's coming in for tea and biscuits with the Chief Pilot.

I was in a commercial aircraft where we disregarded the RA because the traffic was in sight and the human brain was capable of assessing the threat (now visual) rather than a warning of an unseen threat.

Unseen threat or any doubt, then there's no doubt - RESPOND

But firstly 'we' weren't there and secondly surely we must accept that humans can outthink an arbitrary machine - otherwise why are there humans still in the cockpit?

The danger of ignoring an RA is that you assume that the aircraft you can see is the one which triggered the TCAS. The Tcas may be warning of another aircraft which you have not seen.

TCAS II considers service ceiling limitations when issuing Climb RAs:

http://www.pprune.org/tech-log/54781...e-ceiling.html

I think this contribution is the point - Oxenos has put the finger on the nub:

Sort of like the 727 midair with a small Cessna over downtown San Diego September 25, 1978. The 727 crew reported a Cessna in sight. Alas, they saw the wrong Cessna. Killed 144 people, including 7 on the ground (plus 9 injuries on the ground). Until the AAL DC-10 crash at KORD the following year it was the deadliest crash in U.S. history.

This accident gave new urgency for the ultimate development of TCAS.

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?

In this case, it seems like the correct decision was made, no harm...no foul.

I suspect no tea or biscuits this time.

At a previous employer a crew lost 4,000' following an RA due to an antenna fault. And they were not very high to begin with.


Slavish devotion to technology is every bit as dangerous as our well documented human failings.

Golf: Is an RA indeed an advisory? I know what its title is, and similar to some manufacturer's confusing labelling of MCT that is not meant to be unlimited continuous, (see a tech log topic) the use of Resolution Advisory as a title, when in fact it is a Command to act, can lead the Oxford dictionary police to cry foul.
Notwithstanding it may be the wrong a/c you can see, you do not know what TCAS has commanded that other a/c to do. By not following your command you might then become the target for the avoidance manoeuvre of the other a/c and then require TCAS to 2nd guess and issue further commands. If you ignored those, things will be going south very fast. The closing speeds are a blink of an eye and the inertia involved could prevent an avoiding manoeuvre, even if visual. Remember, pulling 4g or turning with 4g will most likely put the threat traffic blind to you, and likewise them to you if they rack it around. Equally a -3g bunt would generate some customer complaints & much paperwork.
Question is, in this day and age of the ever growing world of 3 letter abbreviations, TEM is quite the new fashion. 'If there is doubt there is no doubt' was drummed into me from day 1. It still holds true; so why risk it?

The FAA's position:

https://www.faa.gov/documentLibrary/...-55C_CHG_1.pdf

The nub of the FAA position is:-

"(2) When an RA occurs, the PF should respond immediately by directing attention to RA
displays and maneuver as indicated, unless doing so would jeopardize the safe operation of the
flight or the flightcrew can ensure separation with the help of definitive visual acquisition of the
aircraft causing the RA. By not responding to an RA, the flightcrew effectively takes
responsibility for achieving safe separation. In so choosing, consider the following cautions:
(a) The traffic may also be equipped with TCAS and it may maneuver in response to
an RA coordinated with your own TCAS.
(b) The traffic acquired visually may not be the same traffic causing the RA.
(c) Visual perception of the encounter may be misleading. Unless it is unequivocally
clear that the target acquired visually is the one generating the RA and there are no complicating
circumstances, the pilot’s instinctive reaction should always be to respond to RAs in the
direction and to the degree displayed. "

If you don't like that, why not pop the circuit breakers and get rid of it? While you are there, you might as well pop the ones for the GPWS and the fire warning system and the stall warning and the config warning and the cabin alt warning and all those other things which make an annoying noise. So much nicer with a quiet fl;ight deck.

I do hope those indicating that following a RA is optional aren't pilots, worries the #@*t$ out of me to think they perhaps are.

My advice:

If you think an RA is not needed, follow it anyway. Generally the change to your flight path is quite small.

If there is some compelling reason not to follow it, or not to fully comply with it, do the best you can, in the correct sense. (e.g. Perf inhibitions are very approximate and wouldn't know, for example, that you are covered in ice. Maybe it asks for +1500 fpm and you can only coax +800).

Whatever you do, don't manoeuvre in the opposite sense to the RA. This is massively more dangerous than non compliance.

e.g. The lake Constance collision essentially involve 4 RA's. Only 1 was correctly complied with. 1 was correct sense, but insufficient magnitude. 2 were in the wrong sense.

My take on the term advisory is that it is not mandatory because I don't believe TCAS has a terrain warning included.

If RA says descend, you descend. If you hear GPWS Pull up, then up we go. In this case, the RA is not binding and thus is just advisory, whereas the GPWS is more pertinent..

Only other time I can think of ignoring this is in an emergency descent, possibly with an uncontrolled fire on board and perhaps in the circuit, if visual with all traffic and ATC are providing full coverage. Lastly, if the system is spurious, and only if this is confirmed, then i'll switch it off with a CB. Still not ignoring the RA however.

Failing this, I'M ALWAYS following RA.

Wrong. TCAS RA is mandatory. Unless it jeopardises the safety of the aircraft. In other words, follow it, don't assume the aircraft you can see is the one the TCAS RA is for.

Only other time I can think of ignoring this is in an emergency descent,

It's been thrashed to death before: but why were you not squawking TA Only. Also; how do we know about this non-compliance with the RA. Who told whom and how did the poster discover this snippet?

What does the Company ops manual say? What does the aircraft fright manual (deliberate misspelling) say? TCAS 1 or TCAS 2?
I found some ambiguity betwixt them and found that the subject was not covered well in neither recurrent training nor in sim training. ("we don't have time to discuss must tick other boxes"). Comments?

you mean "flight manual " I guess :-)
TCAS1 is not for airliners, and I do not think it is even manufactured anymore (someone can correct me if I am wrong.) , ICAO/FAA/Eurocontrol mandates ACAS which is TCAS2 .
And yes always follow the RA.
As said here already making visual assessment is no guarantee the one you see is the one giving you the RA.

In this case lots of spin for a known problem occuring quite often : not reducing rate of climb/descent before level off.
As far as I have heard of this incident, the DA50 was cleared to FL360 ( 1000 below the 737) but because of high rate this generated RAs..
Separation was in fact never lost .( as the graph shows ) I would like to see the BFU report on that one , and not Av Herald account .