TCAS climb

[Belowclouds]

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?

[hawk37]

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

Hawk

[Intruder]

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.

[catchup]

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

Regards

[earnest]

......the question is, should you have willingly exceeded a major aircraft limitation in following the RA?
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.

[FlapsOne]

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.

[idg]

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

[SR71]

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.

[Notso Fantastic]

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.

[safetypee]

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.

[Astronomy Dominie]

First, this may be of interest...

TCAS Bulletin (http://www.mfom.es/aviacioncivil/programas/acas_html/ACAS_leaflet_v4_Final.pdf)

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 (www.bluecoat.org) 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

[GearDown&Locked]

From the Airbus Corporate Jetliner
Riding on its aerodynamically advanced wing, the Airbus Corporate Jetliner flies high for maximum comfort and fast for maximum efficiency: cruise is at 0.80 to 0.82 Mach number, and cruise altitude is up to 41,000 ft.

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.

[SRB]

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.

[GearDown&Locked]

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

Type Certificate (http://www.content.airbusworld.com/SITES/Certification_Register/PDF-tcds/A319-A320-A321/SA_DGAC_TCDS.pdf)

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.

[SRB]

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.

[SimJock]

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.

[Muldrake]

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.

[SimJock]

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:

[Belowclouds]

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.

[BOAC]

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.

[SR71]

Just another piece of information that might be helpful and lends credence to my former supposition that indeed max service alts are somewhat artificial.

(Interestingly, in the 737 series I fly, max service alt is FL370 but one may select up to FL420 on the pressurization panel. Seems to me then, from a systems point of view, the restriction limiting the airframe to this level is then either aerodynamic or somewhat artificial. My own experience suggests that certainly at light weights, the aircraft would be quite capable of climbing higher.)

I know that, certainly, on the Smiths FMC, there are relevant PERFORMANCE FACTORS (to the incident in question) which may be selected via the Maintenance Pages.

They are the Min ROC parameters in CLB, CRZ and ENG OUT and the MNVR MARGIN.

These are Management selectable options.

The ranges are:

MNVR MARGIN: 1.15 - 1.60

MIN ROC: 0-999 ft/min

Knowing what the company set these values at might reflect how they perceive the limit.

These values obviously don't change the certified service limit but they do govern how close one may approach the edge of the flight envelope in the various phases of flight.

And IMHO, if the FMC predicted MAX ALT at 58T with a CG location of 15% MAC is 368, it seems quite clear to me that at 50T, the aircraft is capable of going higher than 370 all other things being equal.

Won't help you out of a jam I suppose, but I believe it demonstrates the articial nature of the limitation in question.

That a breach of this limitation should even be considered akin to a breach where a TCAS RA was ignored is lamentable.

:ok:

[GlueBall]

Isn't there a little paragraph in your FOM (Flight Operations Manual) that says something to the effect that: "Policies, checklists and SOPs cannot address every conceivable inflight situation, and that pilots are not restrained from exercising good judgement and common sense?" :ooh:

[Old Smokey]

Good one Glueball,

In an earlier airline, which was run by pilots, at the foot of each page were printed the words "Nothing in this manual replaces good judgement in the field".

A few years before departing from that operator, the lawyers forced it's removal.

Sorry Belowclouds, that doesn't help you does it ? Good luck.

[Captain Kot]

:ok: Well done, BC! And never mind attitude of your , sorry, those company to your actions to stay alive, as well as keep your ND in 40NM range in case of FO-s are permanently in mechanical back-up! ;)

[arba]

On last Prof.Check, TCAS descend while vectored, and level at MSA, scenario (they would think of everything to make us busy)

To me, you've done a great job

[A320CAPT]

Stay cool BC! You've done the right thing responding TCAS RA demand. Otherwise, on professional side of the subject, you would't have been "polite" as a Captain of that flight, would you? That's why our customers pay the bills - to be safe.... well, not only to be safe, but this is number one you've been trained for and are getting your salary!

[Pegasus77]

Hey BC,

First: You did the right thing. You saved your passengers and your own life.

When flying A320, I was taught (I believe by the same people who trained your trainers, can that be?) that the FL391 restriction was due to the pressurization-certification. I know of a case where a captain on our fleet climbed to FL410 without any pressure problems.
A "colleage", who happened to be on the same frequency, telexed the company (instead of warning the before mentioned captain). The CPT was told by our fleet manager, that Airbus -due to the certification- just cannot guarantee enough pressurization at that level.

I doubt the oxy masks can cause the limitation. We use the same on our 340s, which are allowed to climb to FL410 (it only takes hours to get there... sigh).

One thing is for sure: There is no aerodynamical limit at FL391 for the 320-family, nor is the 320-family performance-limited at FL391. Flying in FL400 for a short while is no problem at all.

Shortly climbing to FL400 to adhere to your TCAS-SOP (=standard operating procedure!!!) is IMHO the absolute safest course of action.

Keep strong, keep safe!

P77

[Bumz_Rush]

On this highly automated aircraft, which Gulfstream claim has had vast flight crew input, there are still one or two odd balls.

For example, in the event of a engine failure, the crew must manually change to TA only.
The reason given being that the "computers" do not know the aircraft is sinle engine. And there might not be enough power, etc, to make the required climb.
I am very surprised that this consideration is not built into the software.

In relation to the main thread, has single engine situation, been built into Airbus TA/RA situational awareness.

[Mad (Flt) Scientist]

AC20-131A "Airworthiness Approval of Traffic Alert and Collision Avoidance Systems (TCAS II) and Mode S Transponders" which may be found here (http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgAdvisoryCircular.nsf/0/8C0BC1DB4C158B5E862569B600564222?OpenDocument) provides a range of TCAS manoeuvres (in Table I of the "par3" file) which are to be met in order to permit the CLIMB RAs to be issued by the system. However, it is not considered necessary to meet the requirements as a steady-state manoeuvre - speed may be traded for altitude provided the various speed minima specified are respected.

Assuming Airbus used this guidance material, then of course adequate (aerodynamic) performance must exist to respond to the RA. Unless you're in an unusual configuration there should never be a concern that responding per the RA will cause any kind of handling/performance issues.

[FLEXJET]

On the Airbus 320 family, TA mode will be set automatically when Windshear, Stall and GPWS messages are triggered.
In case of engine failure, the TA mode has to be set manually.