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Crew ignored TCAS RA

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Crew ignored TCAS RA

Old 9th Nov 2016, 10:19
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Originally Posted by Small cog View Post
AercatS2A:

Can I suggest you don't fully understand how TCAS functions below 1000ft? This was reinforced by Eurocontrol in December 2007 by the following ;
Er, what makes you say that? Your quote agrees with my post.
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Old 9th Nov 2016, 11:19
  #42 (permalink)  
 
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Aerocat what small cog is trying to get across to you is that correctly functioning TCAS installation will not generate a Descend RA if the aircraft is below 1,100 AGL. and it will not generate ANY RA once below 1,000 AGL.

When you received the Descend RA at 200 feet and then again while in the flare, something must have been working incorrectly in your airplane, or maybe you misunderstood what was being conveyed to you by the equipment.
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Old 9th Nov 2016, 12:00
  #43 (permalink)  
 
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@Oxenos (post 14)

I fear you have missed part of the quote you posted, thus distorting the FAA Advisory Circular, though the guidance is itself contradictory

12.b. Pilot Responsibilities.
The intent of a TCAS is to serve as a backup to visual collision avoidance, application of right-of-way rules, and air traffic separation service. For TCAS to work as designed, immediate and correct crew response to TCAS advisories is essential. Delayed crew response or reluctance of a flightcrew to adjust the aircraftís flightpath as advised by TCAS due to air traffic control (ATC) clearance provisions, fear of later FAA scrutiny, or other factors could significantly decrease or negate the protection afforded by TCAS. Flightcrews should respond to a TCAS in accordance with the following guidelines when responding to alerts:
(1) Respond to TAs by attempting to establish visual contact with the intruder aircraft
and other aircraft which may be in the vicinity. Coordinate to the degree possible with other crewmembers to assist in searching for traffic. Do not deviate from an assigned clearance based only on TA information. For any traffic acquired visually, continue to maintain safe separation in accordance with current regulations and good operating practices.
(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 pilotís instinctive reaction should always be to respond to RAs in the direction and to the degree displayed.

It also goes on to say

(16) The TCAS alone does not ensure safe separation in every case, nor diminish the
pilotís basic authority and responsibility to ensure safe flight. TCAS does not respond to aircraft which are not transponder-equipped or to aircraft with a transponder failure, and can display erroneous indications when a transponder malfunctions. TCAS RAs may, in some cases, conflict with flightpath requirements due to terrain, such as an obstacle-limited climb segment or an approach to rising terrain. Since the basis for many approved instrument procedures and IFR clearances is avoiding high terrain or obstacles, it is particularly important that pilots maintain situational awareness (SA) and continue to use good operating practices and judgment when following TCAS RAs. Pilots should make frequent outside visual scans while using see-and-avoid techniques. Communication with ATC should be initiated as necessary.
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Old 9th Nov 2016, 12:45
  #44 (permalink)  

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Originally Posted by lederhosen View Post
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?
search for "pop-up" RAs and TCAS altitude sampling rate. Though with the modern equipment it should not have been an issue. So maybe a blind lead.
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Old 9th Nov 2016, 12:59
  #45 (permalink)  
 
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Originally Posted by deefer dog View Post
Aerocat what small cog is trying to get across to you is that correctly functioning TCAS installation will not generate a Descend RA if the aircraft is below 1,100 AGL. and it will not generate ANY RA once below 1,000 AGL.

When you received the Descend RA at 200 feet and then again while in the flare, something must have been working incorrectly in your airplane, or maybe you misunderstood what was being conveyed to you by the equipment.
Yes, that is the point of my post. Did you read it?

Maybe it was unclear. I was providing an example of an occasion where you should not follow an RA. In my example, our RADALT was faulty and the TCAS inhibits were not active when they should have been. Hence we got an RA when we shouldn't have and so we didn't follow it.
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Old 9th Nov 2016, 13:31
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I read Aerocat's initial comment as saying that, because of their height, there was clearly a defect so, of course, the RA was not complied with.
Seems clear to me.
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Old 9th Nov 2016, 13:57
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GOL turned off their transponder
No, the Legacy was the one with the transponder turned off.
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Old 9th Nov 2016, 14:02
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Aerocat, sorry I typed in haste, and having now re-read your post I see the point you are making.
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Old 9th Nov 2016, 15:04
  #49 (permalink)  
 
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golf banana jam

I fear you have missed part of the quote you posted, thus distorting the FAA Advisory Circular, though the guidance is itself contradictory
In fact I deliberately omitted para(1) of the quote, as it specifically relates to TA.
The issue here relates to RAs
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Old 9th Nov 2016, 21:28
  #50 (permalink)  
 
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Reading the last 3 pages illustrates that most pilots today are children of the magenta and would follow the magenta line blindly without asking any questions.

The FAA Advisory Circular posted by oxenos, clearly states that a pilot can, depending on the situation, disregard a RA if there is a good reason to do so or if visual with the RA traffic. Of course, the pilot then assumes responsibility for the deconfliction if electing not to follow the RA commands.

Quote:
"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. "

Now, please explain to me why it is so bad to do as this crew did? If the conflicting traffic was the only traffic nearby, and they had obtained a visual, why not just steer clear?

If this is a professional pilots forum, then maybe one should start acting as pro, fly the f...... aircraft and take some responsibility, instead of following the magenta line blindly like a lemming.

Maintain aircraft control - Analyze the situation - Take appropriate action
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Old 9th Nov 2016, 21:50
  #51 (permalink)  
 
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Also, whatever happened to airmanship? If you fly a high performance jet start thinking about reducing rates of descent or climb as you approach your assigned level and there is other traffic around. Simple airmanship.
Heavens above! Wouldn't that be dangerous? I mean.......you might have to come out of VNAV......would the wings even stay on?
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Old 9th Nov 2016, 21:59
  #52 (permalink)  
 
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Originally Posted by Small cog View Post
Aerocat. While I agree with your valid point regarding an issue with your Radalt info, I don't agree that the other aircraft on the ground had any part in your RA.
That's where the TCAS display showed the intruder to be and there were no other aircraft airborne at the time. That's beside the point though, that a faulty TCAS can give you an RA that should not be followed.
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Old 9th Nov 2016, 22:01
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TCAS targets displayed on our NDs don't have the accuracy of an SSR or ADS-B. So even if the aircraft you see is in the same position as TCAS target, it might not be the only aircraft there or might not be the actual traffic at all.

Obviously there are times when it might be a good idea to disregard TCAS (RA below 900ft in case of equipment quirks as somebody described, etc.), but to disregard it in cruise, just because you think you might be visual with the correct aircraft. Also, TCAS is not a 2.5g manuever, nor does require any abrupt flight control movement - just a gentle pitch up/down to satisfy RA requirements. This of course takes into account that both aircraft compy with RA orders - otherwise the RA commands might require much higher ROD/ROC.

Not to be picky, but the FAA circular has no implication here. EU-registered aircraft operating in European airspace by an EU AOC holder. It is also Boeing procedure to follow any RAs unless below 1000ft or that visual contact requires other action (i.e. you follow RA and it looks something bad will happen anyway).

ACAS II overview | Eurocontrol:

Pilots are required to immediately comply with all RAs, even if the RAs are contrary to ATC clearances or instructions, unless doing so would endanger the aircraft.
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Old 10th Nov 2016, 02:02
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Originally Posted by onceapilot
The subject has nothing to do with mil training or how good you think you are, learn and follow the TCAS rules
That's exactly what I had been advocating - please re-read my post. The funny thing is that often, at the slightest mention of military operations, some colleagues will charge you with the worst possible offences, often in contradiction with what you had been saying

Originally Posted by uplinker
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.
For your information only, that's what fighter pilots are required to perform during air combat - to keep a picture of what's happening above, beside and especially behind. So even if a TCAS can do better (and once again I'm not challenging that) it remains that people from that background will have a better instant understanding of what's happening - which once again, sorry to repeat for some, doesn't preclude following TCAS orders.

There was years ago a fascinating incident when a 747 captain was ordered by ATC to take an avoiding heading related to another aircraft - which he had on TCAS. The turn was to the right, and TCAS was showing the intruder on starboard. So he declined, ATC gave again the same order, which was declined again. ATC shouted an avoiding action, which was more abruptly denied... and so it went, up to a TCAS RA. Simply because the 747 captain (sort of civilian god having paid for his training ) had never heard of a triangle of speeds, or an intercept profile, which every fighter pilot - or Navy Officer out at sea ! - would have been familiar with.
On many TCAS, the bearing provided on the display is not so accurate - it's not an air-to-air radar, like what you have in a Mirage or F16 - but ATC, even the civilian, have all the software behind their screens, for the "interception" not to happen. Calculations are the same than in an air-to-air radar.
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Old 10th Nov 2016, 06:39
  #55 (permalink)  
 
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If the RA is not for the aircraft you are visual with, then surely you have a TA for both? No need to discuss bearing errors and all that. If you have 2 aircraft at +/- whatever, then that's one thing. If only one is showing, that's quite another.

I find it unhelpful to compare this incident to one years ago where they did not have a visual.
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Old 10th Nov 2016, 07:16
  #56 (permalink)  
 
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If the RA is not for the aircraft you are visual with, then surely you have a TA for both?
That assumes all aircraft have operating transponders, which might not be the case. There are many GA aircraft without transponders, or one might be inop, or a student pilot who accidentally left it at STBY, etc.
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Old 10th Nov 2016, 08:23
  #57 (permalink)  

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I've been reading this thread with interest. OK, I'll admit I've been out of the loop for twelve years now, but TCAS saved my butt a couple of times. My take on it is ALWAYS BELIEVE AND FOLLOW THE TCAS. (back to retirement)
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Old 10th Nov 2016, 08:52
  #58 (permalink)  
 
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Herod , " ...... ALWAYS BELIEVE AND FOLLOW THE TCAS"

Even if the ATC shouts to take the opposite evasive action?

Has any one had his TCAS warning to descend and the ATC advising to climb up or vice versa??
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Old 10th Nov 2016, 09:00
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Yes, even if ATC shout the opposite.
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Old 10th Nov 2016, 09:26
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Herod , " ...... ALWAYS BELIEVE AND FOLLOW THE TCAS"

Even if the ATC shouts to take the opposite evasive action?
Are you serious??
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