733 FMC failure

[greenhorn1]

This seems to be a great sim favourite at the moment, any good tips and advice would be appreciated :ok:

[michaelknight]

Yes, this was one they were giving in out command upgrade sims and it did trip a candidate I know up.

I think the old adage 'Fly the aircraft' springs to mind, the 737 dosen't turn into a pumpkin because the FMC fails but it's pretty disorientating when all these amber flags on the ND appear and you're back to pitch and power like a -200.

In our command upgrade, the airport was using RNAV SIDs, and in one of the little notes that most people brush over is 'In the event of RNAV failure, advise approach immediately' or words to that effect. Sure advise ATC, if you start flying all over the sky, they will start asking questions putting you under more pressure, advise them and request radar climb out, and go back to flying the aircraft. Clean up and run through the QRH. DODAR.

You can still continue under vectors or ground based navaids. You can do a CAT III with no FMC. I don't see any urgency in returning to the airport of departure, as you're gonna have to set everything manually, so why not at destination AD than departure. Obviously, it does depend on where your flying to duration, ATC etc.

MK

[BOAC]

...and of course you CANNOT fly in BRNAV airspace..............might make a call to company ops if you are outbound an idea rather than dumping a non-RNAV beastie at an outstation.

[Denti]

Actually you can, with prior permission and special approval by the ATC service provider as well as the relevant authority.

[BOAC]

Yes - been there, done that - but it IS pain and is by no means quick, so you will get significant delays which might affect FTL, hence the value of a call home first!

[Denti]

Absolutely true of course. It is a major pita and takes quite a bit of time. Especially if it is not a domestic flight, crossing borders is nearly impossible in europe without working BRNAV. However there still is a slim chance you might make the flight. Of course never leave your base with any problems like that, but to get back to base it is usefull.

[greenhorn1]

Thanks very much for the replies. I note the QRH does'nt say much except for saying "Resume convential navigation and use the manual N1 knobs "

I presume you are going to have to go to the QRH also for Vref speeds and GA N1 etc.

[captjns]

As long as the IRS's are working and providing information to the FCC's and symbol generators for the glass, and amps for the hard balls, you revert to VOR/NDB (radio) aid navigation. You can even you radar vectors too.

[Boingboingdriver]

If you lose one FMC,initially fly with Heading select and conventional radials to follow then engage opposite side autopilot and LNAV/VNAN will be available again...if you lose both FMCs..well unable BRNAV..
You will have to get speeds from actual grossweight.(QRH)( T/o fuel - burnt fuel) since fmc gets input from the fuel summation unit..

[RAT 5]

Would you not be able to fly <FL290 i.e. non RVSM and fly beacon routes? As someone said, just like the old days. There are plenty of non RNAV & BRNAV a/c flitting around the blue yonder. It's only a computer that makes life easier. It is not a 'must have', but a 'nice to have'.

There was case a few years ago, before the extensive use of RNAV & BRNAV, when an EFIS IRS FMC a/c took off from a northern London airfield to fly to a N.W England airfield on a clear day. VNAV, LNAV, A/T would not engage. I suspect the FMC had gone on holiday. The capatin returned to departure airfield with his 'broken' a/c. Chief pilot asked, "why?" Quite right too.

[BOAC]

Would you not be able to fly <FL290 - I don't know about now, but it stumped BA in 2003 and I believe the flight would had to have been conducted below FL100 as I think BRNAV was then from 100 to 290 and RVSM above, which from Venice to LGW would make for some scenic views of Nice:). On that occasion I 'helped ' the poor besieged BA manager and came back in stealth mode lying like a cheap Japanese watch, as they say.................

Anyway, back to the poor OP - yes, into the QRH and behave like a real pilot! It is actually quite enjoyable.

[Cough]

Now then...RVSM is one thing all to do with height keeping and is not affected at all by the lack of an FMC...BRNAV is all to do with NAV and so is very affected by the lack of an FMC...

Top tips - Always know the power setting for the next phase of flight (approach - think G/A). Does the EGPWS terrain function need to be inhibited? Tell someone (ATC) if its going to help but shuddup if its going to hinder. Final tip - LOOK OUT OF THE WINDOW! It will of course just confirm that you are exactly where you expect to be!

BOAC - I am not going to say anything.....

[BOAC]

BOAC - I am not going to say anything..... - Damn! Should have checked my logbook - what's the current 'hush-up' fee?:)