Do You Follow RAs?

[ferris]

Debate at work about what happens when pilots receive an RA in contravention to an ATC instruction.

1. Do you follow RA?

2. If you do , why?

3. What is your co. SOP?

4. What co. do you work for? (or where do they operate from if you are shy)

6. Has your co. issued clarification/guidance since the Bodensee accident?

5. Do you believe you are legally justified in following RA, and why? (I don't mean "ultimately responsible for the safety of the aircraft"- why is following RA safer/better/more reasonable?)


ICAO seems very vague, individual countries laws are different. Just trying to gauge what those at the coalface actually think/know.

[NigelOnDraft]

1. Yes
2. Common sense / SOP / Regulatory instruction
3. Follow RA
4. See my Handle
6. Reminded us of SOP, in unlikely event anyone needed reminding.
5. See 2 - of course. The Swiss accident likely / partly happened because this was not a universal practice.

TCAS is the backstop for when the ATC system fails us (thankfully rarely). I have yet to know when functioning TCAS, correctly followed by all parties, has increased the hazard. I know plenty of the converse...

Hope of use to you! However, the fact you bring up not following an RA as even an option is hazardous in itself... there must be NO option.

NoD

[ferris]

This is exactly why I am bringing it up.
I was 'surprised' by some of my colleagues beliefs.

ps. What regulations are you referring to?

[mdb3]

You must follow the TCAS, the way I understand how the system works, is that if two acft are on a collision course, the TCAS systems working with the acft transponders, work out the resolution and talk to each other. They will tell one acft to climb and the other to descend. You have 5 seconds to respond and you must attain the commanded ROC/ROD with 5 secs. If the TCAS reverses the command then you have 2 or 3 secs to follow the reversal this could put the CA on the ceiling or the coffee on the floor. If you don't follow the TCAS then you end up with the Bodensse accident. The TCAS system doesn't consult with ATC, thats what the pilot is there for and there are standard phrases to use when the situation occurs.

Someone may have a better understanding of it than I have, but I'll be following the TCAS even if it is contradicts an ATC instruction.

[ferris]

Please, I don't want to get into a discussion about TCAS, just about the rules and how they apply to you.

[Iceman49]

1. YES

2. It's called you bet your life

3. You follow the RA instructions

4. MSP

5. See question 1 and 2 answers

6. You would be a fool not to!

[ironbutt57]

Yes TCAS information is more realtime than atc radar, it also does not depend on a radio transmission that may be blocked...ATC needs instant digital "on screen" information that an aircraft is responding to an RA so as not to intervene and cloud the picture....full stop!:mad:

[Big Dog 2]

Yes I follow RAs
If I/We get an RA then we have come to the last line of defense.
For whatever reasion Crew ATC or both.
If the aircraft involved are given RAs then the TCAS has already resolved the breakdown in seperation.
It is our company SOP to do so.
I have had 1 RA because of another A/c Decending form above
at a high rate of decent.While in the cruise.
We did not even see the other aircraft but watched on TCAS from when it became a TA .
I have also had a nother heavy A/C not show on TCAS at all
The following investigation found the 747 had a us TCAS
and yes I did raise ASRs about both of those incedents
I work for a UK company, Flying mostly in the UK.
I hope this helps in sheding some light on what we see at our end

[Crash & Burn]

From the Honeywell TCAS II handbook:

If a TCAS RA maneuver is inconsistent with the current ATC clearence, the pilot:
* Must not delay responding to an RA.
* Must not modify a response to an RA.
* Must follow the RA maneuver, unless 'implementing' Emergency Pilot Authority.
* Must provide a vertical rate that minimizes ATC deviations.

In answer to the questions above:

1. Do you follow RA? - Yes

2. If you do , why? See TCAS handbook extract above

3. What is your co. SOP? Follow the RA

4. What co. do you work for? (or where do they operate from if you are shy) - Aussie based Company

6. Has your co. issued clarification/guidance since the Bodensee accident? No

5. Do you believe you are legally justified in following RA, and why? (I don't mean "ultimately responsible for the safety of the aircraft"- why is following RA safer/better/more reasonable?)

Yes - TCAS II co-ordinates RA's between your aircraft and other TCAS II equiped aircraft. See this thread here (http://www.pprune.org/forums/showthread.php?s=&threadid=59119).

You don't know if the conflict aircraft is TCAS II equiped or not. At best one aircraft will climb, the other will descend, at worst, your aircraft will get an RA to climb or descend and the other aircraft, if not TCAS equipped, will maintain course.

The TCAS II system works based on you BOTH following the RA and not ATC. If I was in a RA situation I would hope the other aircraft would follow the RA and not do directly the opposite if commanded by ATC. Why would you want to opposite of what a possibly co-ordinated RA is telling you? Going against an RA is a sure way to increase the chances of conflict!

From a legal point of view, the Australian regs here (http://www.airservices.gov.au/pilotcentre/ais/aip/gen/15118.pdf) state:

Resolution Advisory. In the case of a Resolution Advisory the
pilot will respond in accordance with the collision avoidance
manoeuvre prescribed by the TCAS system.

[Plastic Cockpit]

Have disregarded Tcas once in the past. It was obtained on visual approach below the 400 ft Inhibit Rad Alt. An aircraft at the holding point had switched on their Transponder. We considered it better to be on the ground at a busy airport rather than to go around due faulty equipment.

[BOAC]

Ferris - there are REAMS of good stuff on pprune about TCAS, the rules and what to do, particularly from 'Captain Pit Bull'.

Do a search for these, read them and tell your colleagues. Our understanding of the whole picture has increased dramatically since the dreadful accident.

TCAS rules are just like 'both aircraft turn right to avoid head-on collision'. They will work if both aircraft turn right.

CPB - there is a market for your excellent TCAS knowledge, I think.

[ferris]

I have been following the various threads on pprune with interest, and this prompted my disbelief when the discussion turned to it at work. Some of the misconceptions held (at various levels) are 'antique'- to say the least. Working in such a multicultural environment- both controllers and pilots- I am aware that there can be differences based on where you are from.

Just wanted to get my ducks in a row before going further.

[26point2]

Interesting subject, this was my scenario, Level at 4000' in exec jet on radar heading 270 approaching destination. Dark/IMC MSA 2000' Controller calls with urgency in his voice.
"Turn Left now heading180,descend 2000 due conflict"
As our speed was relatively slow, obviously the autopilot would be fairly slow to roll, so i disconnected and and made the relevant inputs... Now with maybe 1500 fpm down and sharp left turn the TCAS calls "TCAS CLIMB" Did the controller send me the wrong way? What do you do now guys??
Now im looking on the screen, Where is it?... I see it. 500' bellow but climbing... Maybe a mile off the nose Do i obey the TCAS? What do you do now guys (and girls) if i follow the TCAS i'll sink a bit more before climbing towards his target level!.... "Implement Emergency Pilot Authority" tighten the turn and within 2 seconds we were passing the same level as i continued the descent. (Enquiry radar trace showed closest as 500' and 1/2 mile) It all happens in an instant, but at the end of the day i was lucky enough to see the conflict and just got out the way... What would you have done?...
(This was several years ago and a long way away.. but true.):confused:

[ferris]

As an aside, I have had 2 aircraft ignore RAs.
Nose to nose, climber assigned level below, descender assigned level above. D asks "who's the traffic"?(obviously in response to a TA). I pass traffic to both, and the plan. As they pass (seperated), the climber says "oh, and we had an RA". I asked the descender, and he agreed he had one as well, but obviously elected to do and say nothing as it might confuse things. After reading the incident report, I learned that the TCAS had wanted the descender to increase descent and the climber to increase climb, something I didn't realise TCAS would do (cross levels). I now know a lot more.

But if you think Bodensee could never happen again, think again.

[BOAC]

"After reading the incident report, I learned that the TCAS had wanted the descender to increase descent and the climber to increase climb, something I didn't realise TCAS would do (cross levels). I now know a lot more. "

I think that goes for all of us, Ferris. If anything good can come out of this dreadful accident, let us hope that at least it is a vastly improved understanding of the way TCAS can work, and if what we read is true, some international standardisation on reaction to RAs.

[RatherBeFlying]

There is a good chance that ATC will become urgently concerned during a TA or RA.

Both a/c follow RA -- OK

Both a/c follow updated ATC instructions -- OK

One a/c follows RA and other follows ATC in accordance with RA -- OK

One a/c follows RA and other follows ATC against RA -- :(

Once RAs are issued, it seems there is an even probability ATC's altitude solution will be opposite to the one from TCAS.

TCAS has been designed with two players in mind -- the crews. But ATC is there too and possible ATC interventions need to be accounted for.

[brain fade]

ATC got it wrong one day, the TCAS saved us. I think its the best thing to arrive on the flight deck since the radalt/GPWS. Luckily I had been exposed to a few RA's which were genuine but not life threatening. Getting the real one made me realise just how good the kit is. Follow it!

[vertigo]

When you do report a tcas manouver to ATC don't forget your callsign ! There is nothing worse on a busy frequency than a disembodied voice calling "WE'VE got tcas, descending"

[None]

1. Do you follow RA? - Yes

2. If you do , why? Company policy and TCAS works

3. What is your co. SOP? Follow the RA

4. What co. do you work for? (or where do they operate from if you are shy) - US

6. Has your co. issued clarification/guidance since the Bodensee accident? Yes; comply with company policy

5. Do you believe you are legally justified in following RA, and why? (I don't mean "ultimately responsible for the safety of the aircraft"- why is following RA safer/better/more reasonable?)

Our Ops Specs require following TCAS RAs to deviate from ATC clearances. Because it is in writing from the FAA and my company, I am comfortable with its legal standing.

Concerning the post from 26point2 above (I realize it was a long time ago when we didn't know much about TCAS), I now understand that it is more important during night IMC conditions to follow TCAS commands (honoring GPWS/impending stall warnings) and not attempt to pick up the traffic visually (night/IMC). As I understand it, TCAS may very well be giving an RA for more than one aircraft. It would be impossible to determine in this case which target on the screen the RA is for.