TCAS climb
 

While flght on A320 TCAS RA brought me from FL390 up to FL400, and now I am under company pressure. They assumed I violate FL391 as enviromental limitation (Volume 3) How can I defend myself?

Perhaps your ops people should put it in writing if they would prefer pilots to respond inappropriately to tcas RA's.

Hawk

Responding to a TCAS RA is an explicitly recognized use of the Captain's emergency authority.

The US FARs address it in Parts 91.3, 91.123, 121.356, and 121.557(a). You will have to find the similar rles if you do not work for a US carrier.

Ask your company, what you should have done else, then preventing a crash with a RA!!!

Regards

He didn't "willingly" exceed it, and I suggest it's not as major a limitation, or threat to flight safety, as colliding with another aircraft.

This is interesting.

I would put the pressure back on the company and try and get them to state, in writing, what they believe you should have done in those circumstances.

If their proposed action would have put the flight at risk (more risk than the TCAS climb exceeding FL391) take it to court if necessary.

I'm no lawyer but I would have thought you would have a good chance of success.

In the meantime it might be nice to know what FL Airbus have actually flight tested the 320 to.

Our 320s are now cleared to 12000 meters FL398. Admittedly they have some computer changes to correct the pressuriation schedule but no other mods were required to the airframe

I'm not in certification but....

I would hazard a guess 390 is a "service" ceiling rather than an "absolute" ceiling.

Isn't the max "service" alt defined by an altitude at which ROC reaches a certain nominal value? (Out of interest, there must be a weight associated with this limitation although I'm not sure what it is?)

What was your ROC in complying with the RA?

If the answer to the second question is a value in excess of the answer to the first question, the a/c (IMHO) wasn't actually performance restricted at that level.

The limitation to my mind is somewhat artificial although obviously if its an SOP one should comply with it.

Oddly enough, I was thinking about this very matter yesterday, because climbing yesterday at a reasonably light weight to 370 (our max alt), my recollection of the ROC at this level lead me to think the a/c was probably capable of climbing higher. Certainly the high to low speed buffet margin was >15kts.

I agree with Intruder's and Earnest's sentiments tho'. Sounds like a fairly valid reason for the excursion in question.

You must obey a TCAS RA. It is reasonable to cruise at your service ceiling. If you then receive an RA to 'Climb', you have no option but to obey- to override that and descend will most certianly put you in direct risk of a collision.

My TCAS instruction book states (under TCAS Inhibits & Limitations): " On individual aircraft types, if in a certain configuration (eg landing configuration) or above some altitude within the normal performance envelope a CLIMB or INCREASE CLIMB RA might lead to a stick shake, those RAs will be inhibited in that configuration or above that altitude; there is no annunciation of such an inhibit."

That the Airbus anunciation was not inhibited near your service ceiling suggests that it is not a problem going higher in an emergency!

In the TCAS RA (Resolution Advisory) Section, it categorically states: "Never manoeuvre in a direction opposite to the RA (further into the red sector), intruder may be TCAS equipped and the manoeuvre will be co-ordinated."

So,
1- Climb to escape danger and exceed service ceiling by a small figure (and avoid collision).
2- Refuse to obey and stay at same altitude (under extreme risk of collision)
3- Refuse to obey and do opposite to RA command and descend (under extreme risk of collision).

I would say that if you were disciplined for obeying a genuine RA in these circumstances, either the Aviation Authorities in the countries your airline visits, or the Pilots Unions in those countries, will be extremely interested and concerned in the practices of your airline's management, and further action may be taken! Some of us transit your airspace and would be most concerned if such practices as your management apparently believe are condoned! We have already seen the effect one aircraft taking the opposite action to an RA can have at Ueberlingen.

Belowclouds, first, what a poor company safety attitude – blame culture. If someone were to just mention which company it was, then they would really see what name and shame means.

Second, if the limit was an AFM aircraft limitation, i.e. Max Alt, then the aircraft manufacturer could have, or should have wired the TCAS to inhibit a climb. However, for some aircraft types this may be delegated to the operator as a manufacturer’s installed option (the operator must request a change), or where the operator inhibits TCAS i.a.w. an approved modification. Thus, seek the facts from Airbus / other operators.

First, this may be of interest...

TCAS Bulletin

Second, you might contact John Law at Eurocontrol - I won't publish his personal address, but [email protected] will reach his team.

Third, I have a feeling that the Bluecoat organisation discussed this a while ago, and a definitive answer (in your favour) was reached, but I can't find the thread just now. You could take a look at Bluecoat and pose a question to one of the administrators.

If the company insist (wrongly) that you should not climb above 390 for TCAS, why not restrict yourself to 380 as a maximum? Suggest to your colleagues that they should do likewise...

Finally, might we have a hint as to which company is involved (PM me if you prefer)?

All the best,

AD

From the Airbus Corporate Jetliner
The a/c in question is the A319. If it can cruise at that alt, the max certified operating alt on both the A319 and A320 should be similar, well above FL391.

It may be the limitation is not due to the airframe or the engine, but to the oxygen equipment fitted. Above 39,000 ft pilots' oxygen masks need a positive pressure breathing facility, below 39k they don't.

Quite a few military aircraft were limited in this way. I can't find the exact spec for the equipment Airbus use - I believe EROS supply it - so if anyone has any technical links I'd be grateful. The FCOMs aren't detailed enough.

SRB - You may be right. Just found that info referring to the "normal" A320; here's the link

Type Certificate

It states, on page 13, that:

MAXIMUM OPERATING ALTITUDE
39,100 ft (pressure altitude)
39,800 ft (pressure altitude) if modified.

The A319 can really cruise higher than the A320/21 due to a modif (page 36 on the same datasheet no180) that allows a 41,000 ft max op alt.

GD&L,

Thanks for that link. I looked into it further but it doesn't support my suggestion. One of the modifications mentioned which allows the A319's altitude of 41k is to do with the placement of the fuel probes - I suspect the other mod is similar.

If a different oxygen regulator is fitted to the EROS mask it should allow operation up to 45k or beyond (provided the airframe and engines do not then become altitude limiting at lower levels).

I must get out more.

I would check with your maintenance guys what the TCAS Altitude Inhibit is set to on your aircraft. Its a wiring option on the back of most TCAS computers, if its set higher than your aircraft performance allows then some re-wiring may be required.

A quick question:

How much is an aircraft supposed to Climb/Descent in a TCAS RA situation, if it is not in a situation where both aircraft is climbing/descending towards eachother

I know the procedure about keeping the V/S needle out of the red zone, until Clear Of Conflict is given. but in a recent incident an aircraft reacted to a RA and it brought him in conflict with two other aircraft not initially part of the incident. First he descended due to an RA. It then triggered a Climb RA due to traffic below, and he ended up violating another aircraft on top of him.

If both TCAS RA affected aircraft changes level by +/- 300 feet, seperation should stil exist with other traffic.

Muldrake

Not really enough information is provided to answer the question, but assuming you have TCAS version 7 (which improved multi aircraft encounters), I would have expected the scenario to run:

Initial Descend RA during or after which time the second aircraft would have been "trafficked", then as the second aircraft threatens an RA your own RA should be adjust vertical speed (no descent) to prevent descent onto the second aircraft or if insufficent separation exists a Climb RA as you say. If the second aircraft is Mode S equipped it should have received a coordinating maneouvre to descend, if its Mode C or no TCAS then your own Climb RA is more likely. Similar situation for the third aircraft.

Given the rough FL's, headings and distances you could run this through a TCAS simulator to evaluate the responses.

If you descend slightly too much you will most likely get the climb RA for the second aircraft, if you don't descend enough (perhaps because you are aware of the second aircrafts position) you will likely get an Adjust Vertical Speed (no descent) part way through the descent, if you descend like a rock then you may get an Increase descent or descend crossing descend to cross the second aircraft flightpath, in which case the third aircraft is probably no factor. If you time it just right you may get a Monitor Vertical Speed with (no descend) for 2nd aircraft and (no climb) for 3rd aircraft. In which case you are the filling in an aluminium sandwich

:hmm:

I appreciate all answers, thank's everybody for backing. I hope it can help, therefore I am about to include in my report everything published hereabove. That's why I am really reluctante to reveal any identity. This is a tricky situation, and I do not want to make it worse.

Good luck, BC! It seems the advice , in summary, is:-

1) Ask why the company has not inhibited the 'climb' RA at 390 if that is what they EXPECT you to do (see post by 'safetypee' on P1 and 'simjock' on P2)

2) Confirm your Company (Ops Manual) REQUIRES you to follow a RA (see 'catchup and 'flapsone' on P1), then back to note 1) and ask why...............


The fact is that 'disobeying' an RA is far more likely to cause an accident than exceeding any particular altitude for a short time (unless the a/c performance is inadequate - see 1), and CERTAINLY manoeuvring AGAINST an RA can be fatal as we sadly saw.