TCAS RA CLIMB on max a/c Celling

[Overheat]

Hello mates.
On my latest check ride I was amazed with one issue.
We're flying an A320 with at FL390 (max). We get a TCAS climb. What do we do?
We climb and maintain the V/S on the green or.... The hell with it, do not risk a high alt and speed stall and hope the other traffic gets and complies with the TCAS descent???

Thanks guys.

Overheat

[763 jock]

So what did you do?

[Runaway Gun]

Coupla hundred feet aint gonna hurt much, surely?

[NigelOnDraft]

Anybody who is willing to climb to FL390 to cruise, and then think following a TCAS RA "Climb" is a problem, surely has their priorities / risk management understanding somewhat adrift

After all, what is the buffet margin at Max Rec Cruise there for

NoD

[Runaway Gun]

To allow for increased load factor due to a turn at x.x G ?

[763 jock]

Follow the RA and miss the oncoming/climbing/descending hardware. Stall at FL410 if you have to, recover by 29000' and you'll still clear Everest.

[GrandPrix]

"cover by 29000' and you'll still clear Everest."

Amen, brutha. (or sista)

[singpilot]

Maybe one of the boffins can clarify, but I think latest S/W has MAX ALT in your TCAS Loaded S/W.

Bummer if the other guy is also at MAX ALT. Maybe one gets the -2000 cue and the other gets the 0 cue.

Someone knows.

But as said, I'd certainly find a way to squeak out a few hun up if that's what the RA cue was.

[aristoclis]

TCAS RA orders must be followed even at max ceiling altitude with CLIMB orders.
Stall warning must be respected.

In alternate law it is not wise to be at FL390. In normal law stall warning does not apply. Alpha protection and Alpha floor do. Get the best your airplane can give you and pray...

[singpilot]

Funny, I wasn't thinking of a Bus.

I was thinking of say.... G4. Civilian Svc Ceiling is FL450. Military ceiling is FL510. Depending on the version, service ceilings can be quite different in 'normal' airplanes.

Yes, the Bus gives you a little more 'help' if you want to call it that with Alpha floor and Alpha Prot. But even that will bite if there is a pax onboard named Murphy.

[Cardinal]

At light weights the Bus can provide your buffet margin well above FL390. The limitation stems from her (in)ability to get down. Even if you had hardly any margin, for whatever reason, pull till she shakes. As Nigel said, priorities.

[singpilot]

Thanks, Cardinal for reminding me of that. Most service ceilings are derived from several performance factors. Newer planes almost always have a dive time problem cuz they are so clean (limiting the altitude that the dive starts at). Or the max number is where you cannot climb by more than some vertical rate.

In a Bus, yes, pull and let the computers do the work.

[galaxy flyer]

NoD

My current plane has about 1.6G at FL450, so your point is? Probably something about larger planes.

GF

[Thai Pom]

I believe the Max Ceiling is pin programmed on the TCAS Processor mounting tray at installation. You should not recieve a RA to climb above this programmed value.

Cheers, TP

[singpilot]

Thanks TP, I was pretty sure that was the case.

[NigelOnDraft]

My current plane has about 1.6G at FL450, so your point is? Probably something about larger planes.

My point is that with 1.6g available, you have plenty of potential to follow the RA.

I might not have expressed it well? To clarify, my point is your priorities are somewhat adrift if you have climbed to a FL where your performance would be so limited that following an RA gives you any concern. You would surely also be considering turbulence, windshear (it terms of W/V altering quickly), engine failure etc. all of which require some tolerance to IAS/M altering somewhat.

And the absolute (rather than current) Max Ceiling will often have pressurisation / fatigue as a factor, which are not applicable here.

Summary: At FL390 in a 320 series Airbus, I am much happier explaining to my Flt Mgr why I went to FL395 following an RA, than ignoring the RA and all the consequences of that

NoD

[Clandestino]

Have a look here. Though they deal with B737, events 5 & 6 are of some relevance to thread.

FL390 is pressurization limit on 320family. If you exceed it, cabin alt will climb as the pressurization controller keeps max diff pressure but that's about it. If sector length wasn't a factor, I never had problems reaching it on 319 with CFM56-5B engines. 320s with -5A were somewhat different story, cruising at FL350 when heavy. Vls is about 1.28 Vs1g when clean, so bus doesn't stall immediately below Vls mark - its the black/red stripe on speed tape that shows your stall margin, not orange one.

I believe the Max Ceiling is pin programmed on the TCAS Processor mounting tray at installation.

Definitively dependent on aeroplane and TCAS computer model. See link above.

The limitation stems from her (in)ability to get down.

Hmmm... I really doubt it. There are no speed or alt limitations on use of speedbrakes and with boards out at Vmo, she dives almost like SB2C. There is a recommendation about not using speedbrakes above FL250 IIRC, for pax comfort though.

[Thai Pom]

Thanks for the link. You are correct there are various ceiling altitude options that can be programmed dependant on Aircraft type.

[FE Hoppy]

This doesn't really take much thinking does it?

Follow RA, miss conflict, explain to fleet chief why you broke a limit.

Ignore RA, So does other guy, hit conflict, no need to explain anything.

If you are at 390 it's because you have the performance to be there.

[captjns]

Some FCOMs state that TA can be selected when performance limited to avoid performance limiting RAs.