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Crew ignored TCAS RA

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Crew ignored TCAS RA

Old 11th Nov 2016, 09:36
  #101 (permalink)  
 
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Surely we didn't just get another story about flying F-16's? If we were in a pub people would be drifting off to another table
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Old 11th Nov 2016, 12:00
  #102 (permalink)  
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Reading some of the posts here makes me almost wanting to give up. The 2001 lessons ( JAL/JAL in Japan and Ueberlingen ) which led to a drastic modification of the ICAO ACAS procedures (i.e basically always follow the RA) , seemed to be forgotten , and we are slowly getting back to square one.
Seeing the number of RA non-compliance serious incidents on the raise again, it is only a matter of time until we will have a most serious case.
Good example (repeat of Ueberlingen scenario) here : http://www.mot.gov.sg/uploadedFiles/...2015-11-11.pdf

When I see F/As injured as a result of following a TCAS RA I wonder if the guy in front even read the manual...
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Old 11th Nov 2016, 12:20
  #103 (permalink)  
 
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Surely following an RA is NEVER dangerous (unless it is to descend below Safety Altitude), NOT following an RA MAY be dangerous. Hence following an RA is ALWAYS safe (bearing in mind the caveat of Safety Altitude). Not following an RA MAY be unsafe, so don't do it, it can never be justified on safety grounds: always, always, always, follow the RA and be SAFE.

Simple really
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Old 11th Nov 2016, 12:31
  #104 (permalink)  
 
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If that's the most relevant example the F-16 can recall which supports his argument that a pilot's first reaction to a TCAS RA is to comply, he misses the point.

In my example of a TCAS RA which occured recently, we could NOT see the airplane that was overtaking us from behind and above while both of us were in a descent while under ATC control.

Unlike the beautiful F-16, the venerable 737 has no field of view behind the wingtip or indeed behind or below at all.

Therefore a commercial jet pilot's first reaction should be to comply with an RA just in case . We do not have an ejector seat or parachutes, and neither do any of the other 195 souls on board.

As for the 737 pilot who caused injuries to crew due to his over-reaction to the RA, this is still preferable to no reaction at all.
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Old 11th Nov 2016, 13:20
  #105 (permalink)  
 
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Surely following an RA is NEVER dangerous (unless it is to descend below Safety Altitude), NOT following an RA MAY be dangerous. Hence following an RA is ALWAYS safe (bearing in mind the caveat of Safety Altitude). Not following an RA MAY be unsafe, so don't do it, it can never be justified on safety grounds: always, always, always, follow the RA and be SAFE.

Simple really
Not that simple.

An example was given up-thread (#35) of a case where following an RA would have been dangerous. In the case quoted, the danger was (a) obvious and (b) due to equipment failure external to the TCAS, but that doesn't alter the fact that the TCAS could and did give an incorrect indication which should not have been followed.

If you always, always, always follow an RA, what are you there for? Why isn't the TCAS linked directly to the flight controls to make the aircraft do what it says? Because nobody with any sense trusts any automatic system to always, always, always work correctly. 99% of the time, maybe 99.5%, but not 100%. The 0.5% is why you're there, and why the ICAO document says "Nothing in the procedures specified ... shall prevent pilots-in-command from exercising their best judgment and full authority in the choice of the best course of action to resolve a traffic conflict or avert a potential collision." To adapt an old saying, engage brain before operating controls.

In this way, TCAS is much like a car's satnav (though much more complex). 99.5% of the time your satnav gives you correct guidance. The 0.5% is when it tells you to drive off the dock into the water.
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Old 11th Nov 2016, 13:47
  #106 (permalink)  
 
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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.
Quite, but with one aircraft on the scope at the correct bearing and no other traffic, it was safe to assume as you can only get a warning from traffic that shows.

Exactly my point regarding having a human on the flight deck . . . Also my point that if there is doubt, then there is no doubt.
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Old 11th Nov 2016, 14:10
  #107 (permalink)  
 
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Our QRH says:

In the event of a ......... RA accomplish the following by recall:

and then details how to mn'vre in more detail.
There is no discretion.

F16 guy - I have the distinct impression that you're 12 , and playing an ego game.

Remember that many of us probably have more single seat time than you so no need for the war stories. TCAS and GPWS equipment failure or erroneous displays are almost unheard of nowadays and many int'l airports are so busy that to even consider not following the TCAS (which is now very sophisticated) could cause a fatal delay.
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Old 11th Nov 2016, 14:18
  #108 (permalink)  
 
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OldLurker,
Having reread #35 as you must have done and reread my caveat about not descending below SA, yes it really is that simple and yes you will get a descend below SA, which is why you and I are there.
There is no excuse for not following an RA (unless SA impinges on your trajectory and you would fly into the ground)

Brian W May: You can never be sure that the one you have seen is the one TCAS RA is alerting you to, nor that simply because the 'scope' sees one there is ONLY one.
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Old 11th Nov 2016, 15:28
  #109 (permalink)  
 
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Like anything...

Lack of knowledge and the 'surprise part' usually induces OVERREACTION !!!
See this over and over again during sim training.

TCAS compliance needs education and REGULAR TRAINING.
(Just like our half-yearly, regular engine failure procedures training.)

Relax... People in the back (should) not even notice a reacting on a TCAS RA . . .
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Old 11th Nov 2016, 15:38
  #110 (permalink)  
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Guys, this is an academic discussion . I am following TCAS from the ATC side since its introduction, and I have never seen or heard of an RA that , if followed would have resulted in an accident , even with initial version 6.04 which was quite bad.
But there are almost a hundred cases by now where not following and manoeuvring against it caused loss of separation , and even a collision ( Ueberlingen)

Anyway the future will solve this , on the A380, A350 (and I believe on all the neos but not 100% sure ) the ACAS is embedded in the Flight Director , so RAs are automatically flown by the auto pilot.
Of course there is a button to disconnect , but I have never heard of anyone doing that in real life. Crew operating those aircraft in their vast majority praise the system .

learner001 : just saw your post ; 100% with you there . Good reminder !

Last edited by ATC Watcher; 11th Nov 2016 at 15:39. Reason: new post from learner001
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Old 11th Nov 2016, 16:09
  #111 (permalink)  
 
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The A380 has an automated TCAS system that reacts to an RA (former instructor). To my professional pilot colleagues: if you do not react appropriately to a TCAS RA you are criminally irresponsible and should not be doing the job. What part of that is difficult to understand?
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Old 11th Nov 2016, 16:47
  #112 (permalink)  
 
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And another thing: for all the 'aces' out there. As we all (should) know TCAS RA manoeuvres are practiced and examined through the mandatory recurrent LPC system here in the UK. The TRE will be looking for the correct response to the simulated RA. Why not try ignoring the RA and tell the examiner that you are going to visually miss the traffic? See how that goes. I find it unbelievable that professional pilots do not understand the imperative of correct response to an RA. It disturbs me that I share the same airspace.
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Old 11th Nov 2016, 18:45
  #113 (permalink)  
 
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Despite this being a "rumours and news" page, the moderators have allowed stupid trolling posts that attempt to undermine the sound basis of TCAS SOP. Mods, please remove posts that advocate anything other than compliance with TCAS SOP. Thanks
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Old 11th Nov 2016, 19:29
  #114 (permalink)  
 
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Should the Mods also delete the quoted FAA and ICAO regulations as "non-kosher"?

Seriously, why are some guys throwing a fit, just because someone has a different opinion. Take chill pill, it's just a discussion!
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Old 11th Nov 2016, 19:53
  #115 (permalink)  
 
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Because these different opinions have killed people in the past, that's why.
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Old 11th Nov 2016, 20:31
  #116 (permalink)  
 
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Take a chill pill? You are kidding but more like trolling.

There is no discussion!

Please do as you advocate on your next sim detail and decide not to follow an RA, the sky will be a safer place for us all.
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Old 11th Nov 2016, 20:36
  #117 (permalink)  
 
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Originally Posted by Sidestick_n_Rudder
Should the Mods also delete the quoted FAA and ICAO regulations as "non-kosher"?
The problem with the weasel words in the ICAO docs is that they are intended to allow a pilot to not follow an RA if it would be more dangerous to do so than to risk a collision, example: getting a "climb" RA that is beyond the performance of the aircraft. But some pilots, like F16 above, think it means they can basically do what they want. If they think they have full SA then they can do a non RA manoeuvre instead. That is not the case though, if it is a genuine RA and it's not going to put you into the ground or cause you to stall, then FOLLOW IT! More importantly, if you, for whatever reason, won't, or can't follow it, then do NOTHING, don't do a non TCAS manoeuvre in an attempt to avoid the target aircraft.

If there are so few aircraft in the area that you think you can positively identify the intruder aircraft then you won't come to any harm by following the RA. If there are enough aircraft around that you can't positively identify the intruder aircraft then you must follow the RA. In both cases, just follow the RA.
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Old 11th Nov 2016, 21:21
  #118 (permalink)  
 
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Why isn't the TCAS linked directly to the flight controls to make the aircraft do what it says? Because nobody with any sense trusts any automatic system to always, always, always work correctly. 99% of the time, maybe 99.5%, but not 100%.
Newer models of Airbus have automated TCAS systems. The aircraft will take evasive action all by itself.

Enhancing flight safety during TCAS manoeuvres
20 AUGUST 2009 PRESS RELEASE
Enhancing flight safety during TCAS manoeuvres

Following recent successful development testing, a new Auto-Pilot/Flight-Director (AP/FD) TCAS* mode for the Airbus A380 has been approved and certified by the European Aviation Safety Agency (EASA).

The main benefit of the system is that it could further enhance safety during a traffic avoidance situation because the pilot can now fly the aircraft without switching out of one mode and into another. Thus, by simplifying the actions required by the pilot during a TCAS manoeuvre, this enhanced TCAS mode minimises potential overreactions or inverse reactions while preserving his or her concentration at a critical time.

In addition to now being certified on the A380, the AP/FD TCAS mode will also become available for retrofit on other Airbus Fly-By-Wire aircraft in the coming years.

AP/FD TCAS operation overview
The new AP/FD TCAS mode essentially completes the existing TCAS functionality by implementing a TCAS vertical guidance feature into the Auto Flight computer. The result is that now the Auto Flight computer can control the vertical speed of the aircraft which is adapted to each resolution advisory acquired from TCAS.

Moreover, with this new AP/FD TCAS mode activated, when a TCAS "Resolution Advisory" (RA) is received, the pilot no longer needs to disengage the autopilot or Flight Director before conducting the TCAS manoeuvres. Rather, the autopilot can now automatically conduct the correct TCAS manoeuvre, to position the aircraft clear of any potential traffic conflict.

Furthermore, in the case of the pilot flying the aircraft manually (i.e. without autopilot engaged) when a RA is received, previously the Flight Director 'pitch bar guidance' - indicated on the Primary Flight Display - had to be switched off, but with the new mode, the Flight Director bars remain active and smoothly guide pilot to fly the TCAS manoeuvre. At any time, the crew still retains the ability to override the proposed manoeuvre, so as to respond manually to a TCAS RA by flying according to "conventional" TCAS procedures, i.e. manually controlling the vertical speed by referring to TCAS indications on the pilot's vertical speed scale.

* Background to TCAS - Editors' note:
The 'Traffic Alert and Collision Avoidance System' - known as 'TCAS' - is designed to scan for, detect, and interrogate the transponders of other aircraft in the nearby airspace vicinity. It then uses the received transponder signals to compute a distance, bearing and altitude relative to the nearby aircraft. The evaluated traffic information is displayed as symbols on the Navigation Display. As TCAS checks the other aircraft?s relative distance permanently in short-time intervals, it can, therefore, also calculate the other aircraft?s closure rate relative to its own aircraft position. When TCAS detects that an aircraft's distance or closure rate becomes critical, it generates aural and visual annunciations for the pilots. Mandated on aircraft carrying more than 30 passengers since 1993, TCAS is now compulsory on all aircraft types.
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Old 12th Nov 2016, 07:05
  #119 (permalink)  
 
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Originally Posted by ManaAdaSystem
Newer models of Airbus have automated TCAS systems. The aircraft will take evasive action all by itself.
Originally Posted by Aerocat
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.
I wonder what additional protections the AirBus system has to avoid the situation mentioned by Aerocat?

Last edited by Basil; 12th Nov 2016 at 12:46. Reason: Sp.
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Old 12th Nov 2016, 07:32
  #120 (permalink)  
 
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I don't believe it's possible to get a Descent RA that close to the ground. The system will have switched to TA only by then I think.
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