Dual fmc failure
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Hi.
If your plane is certified to fly in RNP-10 (very popular in Boeing), in my modest oppinion you donīt need to say anything at all.
You will have to take into acount the abnormal procedures as you have read above from the rest of Ppruners.
You are not in a situation of May day, Pan etc etc etc. Keep calm and take it easy.
Regards.
If your plane is certified to fly in RNP-10 (very popular in Boeing), in my modest oppinion you donīt need to say anything at all.
You will have to take into acount the abnormal procedures as you have read above from the rest of Ppruners.
You are not in a situation of May day, Pan etc etc etc. Keep calm and take it easy.
Regards.
Per Ardua ad Astraeus
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So - it was a 777? Wat about an ATR? An Embraer? A TU. Lets take a 737 Classic - 2xFMC fail - out with the paper stuff. No waypoints, no present position, no 'navigation', no perfomance data. You will have a lat and long position on the INS panel so you'll know where you've been. .All maneagble, however, of course. 777 a bit smarter.
- no - the question was about the FM Compouter, nor the FM System. I never even considered an FMS.failure - the FMC is just one part of the FMS
may have confused FMS with CDU
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The nice TRE a few weeks ago failed both FMGCs on an A320. Then our slats jammed during the procedural approach ILS into Malpensa. The extra fun bit? The loss of both FMGCs mean you don't get VFEnext displayed, so you better start writing down VFEnext-5 for all your flap stages. While trying to remember how you manually tune the radios 
Of course no A/P A/T.
Oh, and procedural ILS was due to the radar having been knocked out by the storm over the airport (and all the alternates). Needless to say, a missed approach would have been interesting (for those of you who know MXP...).
Skipper and I fell asleep about 5 minutes after getting into the taxi from the sim building
I know thread drift, but worth sharing a beautiful sim moment.
P
Of course no A/P A/T.Oh, and procedural ILS was due to the radar having been knocked out by the storm over the airport (and all the alternates). Needless to say, a missed approach would have been interesting (for those of you who know MXP...).
Skipper and I fell asleep about 5 minutes after getting into the taxi from the sim building
I know thread drift, but worth sharing a beautiful sim moment.
P
Funnily enough, I had a dual FMC failure at about 30W. returning to the UK yesterday morning. A few alerts, a/p, a/t drop out and a few odd FMA annunciations, put newspaper down, engage hdg sel, alt hold, carry on. FMC's elected to rejoin the flight twenty min later.(747 a/c).
Thread Starter
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Thanks all for your inputs.
I do agree there is no need for a may day call, and your rvsm should not be affected depending on the type of aircraft. Some aircrafts do allow you to reengage the autopilot.
I do agree there is no need for a may day call, and your rvsm should not be affected depending on the type of aircraft. Some aircrafts do allow you to reengage the autopilot.
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And if ever you're mid Pacific and lose all your FMC(S) and all nav capability, you could (B747) still select A/P, ALT-hold, select HDG bug and steer magnetic course according to your computer flight plan way points data. Imagine! 
Once we lose....
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Manual Reversion
Seems to happen every now and then with the Honeywell FMC fitted to the 744; an FMC glitches, and both FMCs seem to snooze while the 'good' one attempts (usually successfully) to re-synch the 'glitcher'. Far less common on the 777, where the FMC is in fact an FMCF within AIMS, and is inherently far more reliable.
Dude
Funnily enough, I had a dual FMC failure at about 30W. returning to the UK yesterday morning. A few alerts, a/p, a/t drop out and a few odd FMA annunciations, put newspaper down, engage hdg sel, alt hold, carry on. FMC's elected to rejoin the flight twenty min later.(747 a/c).
Dude
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737NG - Dual FMC failure, no longer PRNAV/BRNAV. RVSM Maintained. A/P will not disengage, however LNAV and VNAV cease to function obviously. ALT HOLD Maintains altitude, HDG SEL for radar vectors and VOR/LOC for pretty much everything else. Set up ref and N1 limit manually with the selectors situated above the upper DU and refer to the QRH PI for the figures. Had it in the sim 8 months ago.
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Before FMS was first introduced into TriStar operations - we were very happy with Radio Nav (VOR etc) around Europe, INS display for Long Haul Ops, (Cross Track Error & Desired Track) & Manual Thrust in the cruise everywhere. After the intoduction of FMS, some wondered how we had coped before hand.
Only Airbus could design an aircraft which fails the autopilots when the FMGCs fail though.
Only Airbus could design an aircraft which fails the autopilots when the FMGCs fail though.
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In addition to my last thread:
Dual Fmc fail over Pacific....no issues again.
Last route is already in the box. Use Alt hold on AP,then Track sel to fly the magenta(which should already be displayed on your ND due no erasure of waypoints not passed already). If you are on the magenta,use Lnav. Vnav will not be available. Only problem arises if you wish to divert to an airfield which would be beyond Vhf coverage of your Vor's(typically on trans pacific routes!).In which case you've got to punch in the coordinates of the airfield in Lat/Long mode and you will get the magenta to fly you direct to the airfield in question.After that its simply a matter of engaging Lnav. Like someone said earlier,no Vspeeds or maneuvering speeds.Therefore the handy dandy...
Off to mah beer now...
Dual Fmc fail over Pacific....no issues again.
Last route is already in the box. Use Alt hold on AP,then Track sel to fly the magenta(which should already be displayed on your ND due no erasure of waypoints not passed already). If you are on the magenta,use Lnav. Vnav will not be available. Only problem arises if you wish to divert to an airfield which would be beyond Vhf coverage of your Vor's(typically on trans pacific routes!).In which case you've got to punch in the coordinates of the airfield in Lat/Long mode and you will get the magenta to fly you direct to the airfield in question.After that its simply a matter of engaging Lnav. Like someone said earlier,no Vspeeds or maneuvering speeds.Therefore the handy dandy...
Off to mah beer now...
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If your plane is certified to fly in RNP-10 (very popular in Boeing), in my modest oppinion you donīt need to say anything at all.
Moderator
we were very happy with Radio Nav
.. and, if all else fails (as it often used to do on the Electra from Oz to UnZud) the radar works real fine to find the coastline.
If that failed the cloud gave the place away anyway.
.. and, if all else fails (as it often used to do on the Electra from Oz to UnZud) the radar works real fine to find the coastline.
If that failed the cloud gave the place away anyway.
From some notes I wrote up a while ago for 737:
Failure on the ground or for a return to base:
Experience shows that most FMC failures are of short duration, so it's worth checking it periodically by selecting INIT/REF or similar to confirm its status.
Failure on the ground or for a return to base:
- MEL 2-34-27 applies
- Our OPS MAN require MNPS routes to "be avoided"
- Flight without MNPS is not normally permitted in B-RNAV (RNP 5) airspace, but it is usual to obtain approval to proceed to a repair airport with ATC approval. (Jeppesen text, ATC pages 551-554)
- Repetitive Flight Plan (RPL) must be cancelled, and a new plan filed with "S & R" in item 10 removed and "STS/NONRNAV" entered in item 18
- The phrase "Negative RNAV" must be appended to each radio message initiating contact with each new ATC frequency.
- Take-Off and climb: standard schedule (280/0,79 for -300 or 280/.78 for -700)
- Required to manually set N1 bugs. On take-off set take-off thrust on PF's bug and MCT (for engine failure) on PNF's bug.
- Autothrottle not available for take-off. Climb power is available by setting autothrottle to arm and pressing N1 selector at acceleration altitude.
- Pitch modes available: TOGA, LVL CHG and V/S (ie no VNAV)
- Above FL150 disengage autothrottle (or deselect N1) and periodically bug & set the climb N1 on both N1 gauges as per the MAXIMUM CLIMB % N1 page in the QRH (As the PMCs are using engine inlet temp & pressure data, and being conservative, a significant performance degradation occurs in the climb thrust if you leave the autothrottle engaged without climb performance data from the FMC.)
- standard cruise speed from QRH (LRC in our company, but fixed Mach for others)
- Approaching cruise level extract target N1 from QRH FLIGHT WITH UNRELIABLE AIRSPEED/TURBULENT AIR PENETRATION (CRUISE) chart and bug this on PFs N1
- Extract limit N1 from MAXIMUM CLIMB % N1 QRH page and bug on PNFs N1
- Autothrottle may be used to maintain cruise.
- Inform ATC not RNP compliant.
- Approaching descent, calculate top of descent point QRH 0.74/250 DESCENT SPEED (ALL ENGINES) chart
- Prior to descent, set the Vref speed using the QRH VREF Chart
- Once the ATIS is received, set the N1 bugs to cover a missed approach from the QRH GO AROUND % N1 chart.
- Standard descent schedule (0.74/280/250)
- Auto-throttle can be used for descent & approach
- In the event of a missed approach, pushing TOGA will cause the auto-throttle to disengage. Manually set thrust, The flight director will display correct TOGA commands.
Experience shows that most FMC failures are of short duration, so it's worth checking it periodically by selecting INIT/REF or similar to confirm its status.