Go Back  PPRuNe Forums > Flight Deck Forums > Rumours & News
Reload this Page >

Reaction to TCAS RA

Rumours & News Reporting Points that may affect our jobs or lives as professional pilots. Also, items that may be of interest to professional pilots.

Reaction to TCAS RA

Old 9th May 2009, 01:07
  #41 (permalink)  
Join Date: Dec 1999
Posts: 182
Likes: 0
Received 0 Likes on 0 Posts
guys thanks for the response. sorry i don't log on very often so it's a while ago that you gave me your comments. they were very informative.

surely atco's should be trained on what a pilot is doing when they call 'tcas ra'. could this be a failing in the training. if i am following an RA i really don't want someone telling me there is no problem, i mean, it's nearly a hint not to follow the RA. i am telling the atco i am following an RA so they know why i'm climbing instead of descending, I'm not asking for another instruction, or even a hint at an instruction. i just want procedure...then there will be distractions for me.

Your comments on the confusion from the atco who beleived he had everything under control are very informative and show an understanding of human behaviour. this i fully understand. i think i would react the same way now that you explain it to me. but i guess i would 'train' that reaction out of myself once i realised that i was causing furthur confusion for the pilot during a time when he has limited capacity.

i guess we all strive to be better, and as i said already, at least when i am in uk airspace i know i am dealing with the best. and one thing that makes you the best, is that you strive to get better

Bomber Harris is offline  
Old 9th May 2009, 13:04
  #42 (permalink)  
Join Date: Aug 2007
Location: dorset
Posts: 6
Likes: 0
Received 0 Likes on 0 Posts
As a developer of ATC safety nets equipment and a sometime pilot, it's also important to point out that normally the pilot is following ATC instructions while in controlled airspace. If a TCAS RA is indicated the pilot should report it and report when the TCAS RA encounter is completed - clear of conflict. Downstairs, ATC are hopefully watching their radar display. They may already be noticing the potential conflict and be about to issue avoidance instructions that are contradictory to the sense (climb/descend) of the RA instructions. Hence by notifying ATC, the pilot should not be given instructions by ATC, in order to avoid a conflicting set of instructions being given.

Remember also, that Short Term Conflict Alert (STCA) is fitted in many ATC units. This is a ground based conflict prediction system that uses radar derived positions and flight levels, calculated tracks and ground speeds, as opposed to TCAS, which is airborne. STCA may also be predicting the loss of separation and this is unknown to the pilot, until an instruction is given by ATC. On most systems, ATC do not know that the pilot is experiencing an RA. Some later systems have the capability to downlink the TCAS RA indication and sense and display this on the radar display, on the label information for the target. This requires a TCAS equiped aircraft, a Mode S equipped aircraft, a Mode-S radar, and a Mode-S capable ground surveilliance system. When the TCAS RA label is displayed, perhaps even at the same time as a STCA warnings, ATC now know that the pilot has been given an RA to follow, even if the pilot has not reported it.

All the information I can find is quite simple.
If the pilot is given an RA, he follows it, deviating from ATC clearance if necessary. He/She informs ATC. ATC monitor the situation. After encounter pilot reportes RA over and ATC will then manage the situation, since it's likely that the aircraft has departed from the assigned flight level.

Presumably airlines write these instrucitons into their operating procedures - not being a commercial pilot I don't know.

There's no need to call PAN PAN PAN, MAYDAY or whatever. The TCAS system is designed to give appropraite avoidance instructions. Obviously, if ATC, pilots, and systems never made mistakes, or took their eye of the ball, we wouldn't need such a system. It's just another safety net, like the height between you and mountains below.
aprildavy is offline  
Old 9th May 2009, 17:06
  #43 (permalink)  
Join Date: Jan 2008
Location: Hong Kong
Posts: 100
Likes: 0
Received 0 Likes on 0 Posts
1/ Aviate
2/ Navigate


3/ Communicate.

Why do people try to make this rocket science?
GE90115BL2 is offline  
Old 9th May 2009, 18:09
  #44 (permalink)  
Join Date: Apr 2001
Location: South of Brittany
Age: 73
Posts: 73
Likes: 0
Received 0 Likes on 0 Posts
Reaction to TCAS RA

Do you know ,compared to the full number of reports ,the percentage of TCAS RA which occurs without any conflict.....? and sometimes with only one aircraft present...,
A7700 is offline  
Old 9th May 2009, 23:25
  #45 (permalink)  
Pegase Driver
Join Date: May 1997
Location: Europe
Age: 72
Posts: 3,258
Likes: 0
Received 0 Likes on 0 Posts
A7700 : not much I agree , but in a very few instances it saves the day. this is why so many still back up the system.

aprildavy : On a global scale :STCA is only avail in a handful of ATC stystems and radar cover far less than 20% of the world airpace . TCAS works everywhere. RA downlink is not a global solution.

Now , after Ueberlingen and the very near end of 677 in one go over Japan in 2001, where in both cases pilots decided to act, for different reasons, opposite to an RA, it open the eyes of some regulators that all was not well in TCAS training land, as a result procedures haver been made clearer and widely publicised to everyone.

The post here would indicate otherwise.

2 areas of misundersatnding howhever in many heads :

For Pilots :

If you have an RA, as a pilot you have to follow it , and advise ATC , and from that moment ATC CEASES TO BE RESPONSIBLE FOR YOUR ANTI COLLISION. So forget ATC and follow your RA.
If you decide not to follow your RA ( for whatever reason , you're in charge ) NEVER EVER manoevre in the opposite direction of the RA.

For Controllers :
an RA is not necessarily coming not because you made a mistake , (it can be , but it is not , and by large the majority of the cases) but because THE SYSTEM detected a risk of collision. Let the system and the pilots do their bit AND DO NOT INTERFERE.
If the clerarance you issued was safe , but a pilot manoever with excessive vertical rate and TCAS issue an RA, let it be. Who is to say for 100% that the pilot will stop at the level you instructed anyway?
TCAS is not there to ensure ATC separation, but to prevent aluminum to touch. In doing so it can distroy your plan and reduce your planned separation. But it is not your call.

TCAS is a last minute electronic safety net, nothing else. The least you interfere with it the better.If everyone would understand that, we will have made a great step forward.
ATC Watcher is offline  
Old 10th May 2009, 02:46
  #46 (permalink)  
Join Date: Jun 2001
Location: Fragrant Harbour
Posts: 4,783
Likes: 0
Received 0 Likes on 0 Posts
Quote Phil from the USA: "Kind of curious as to the RA criteria in terminal airspace. Here it is pretty routine to have 500 foot separation between VFR piston and transports".

Two of my four TCAS RAs were in the airspace just to the North East of New York where you tend to cruise for an extended time at 16,000' in a Victor airway in just those circumstances. IFR traffic mixing it with VFR traffic at 500' levels. One RA against a twin coming the opposite way at 500' lower ended up with us in a climb and triggering another RA in an aircraft above us. The controller asked us why we had responded to the RA when we should have seen it would cause problems!

And before the usual US posters point out that it has always been that way and if we can'r hack it, we should stay out of the kitchen - or some other comment, I would like to point out that as a UK operator, we had no choice but to respond.
Dan Winterland is offline  
Old 10th May 2009, 05:34
  #47 (permalink)  
Join Date: Dec 2008
Location: FL400
Posts: 32
Likes: 0
Received 0 Likes on 0 Posts
I am very glad that you do respond to every RA,
I personally think that there would be absolutly nothing worse to have a mid air colision or even a close call and the best reason that anyone could come up with is that this is how things are done in this airspace.

I think that there is a reason why this equipment exists and each and every single RA should be followed religiously.
jacek_flying is offline  

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell or Share My Personal Information

Copyright © 2023 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.