PPRuNe Forums - Dual fmc failure

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Quote:

Originally Posted by Intruder (Post 9429241)

You made the statement, so maybe you can provide the link...

Gee, I wonder if I would be asking for a reference/link if I knew where it was.

Quote:

Originally Posted by Intruder (Post 9429241)

How long does it take to get overflight approval and an entry window for a Russian route?

I guess you will find out when it happens. But may very well be worth the effort and if it doesn't work, at least you can say you tried if questioned about it.

Talked to a pilot who was a crew member on a flight (his previous company) that was deliberately flown from the company base to destination and returned back with both FMGCSs inop. A320. 2 hours flight in radar and VOR enviroment. No AP, FD, A/THR, reference speeds, picture on ND, anything that comes from any part of FMGCS. First company flight to a new destination. TV reporters on departure and arrival. Of course ATC had no idea. In fact nobody had except the cockpit crew, maintenence and Fight Operations managment.
Cessna-320.

Quote:

Of course ATC had no idea.

What did they file on the ATC flight plan under RNAV capability?
https://www.ippc.no/ippc/help_fpl.jsp

"Other reasons for special handling by ATS shall be denoted under the designator RMK/. PBN/ Indication of RNAV and/or RNP capabilities."

That was my question, too, Goldenrivett. At the very least, ATC SHOULD have been aware. Then again, if this was a conversation over a PBR at the hotel bar, I'd discount over 91% of it.

Quote:

Flying below MMEL for a publicity stunt. Sadly by far not the only company in this world that would do such things.

NEWYEAR quoted this a while back

Quote:

Yes you can be RNP-10. In the following cases:

6.2 hours after placing IRU in navigation mode (pure inertial), or
5.9 hours after the last automatic DME/DME position update, or
5.7 hours after the last automatic VOR/DME position update.

The FMS continuosly monitors input from the available naviagtion sensors (radios, IRUs, and GNS) to compute a position and actual navigation performance "ANP" value in units of nautical miles. The FMS RNP function is used as a integrrity monitor for airplane position.

If the plane is certificated to fly in RNP-10 airspace then, you can fly without GPS for a flight time not to exceed:
6.2 hrs.
5.9 hrs.
5.7 hrs.

What aircraft is this for, and if not aircraft specific where do you find these details? Never seem them in the 777 FCOM or other documents.

I'm happy enough that on a 777 the loss of both FMC really isn't that big a deal since the CDUs have the current route and any arrival already programmed in their memory, plus ALT NAV lets you program via LAT/LONG. Positional info now just via ADIRU, and slowly degrades over time when out of nav beacon range.

777 just could basically continue (specific airspace dependent), still RVSM, inform ATC (No Mayday probably not even a PAN), and request radar vectors at the far end. Performance from the QRH plus the trusty 3x table.NATS/Oceanic and Polar however are another issue :)

For the 744 (from our FCOM):

Quote:

Two IRUs in conjunction with one FMC and two FMS-CDUs meet the
requirements as the sole means of navigation for flights up to 18 hours duration.

There are no time limits in OpSpec B036 or B039, as long as GPS or DME/DME updating is operational upon entering airspace requiring LRNS (Long Range navigation System), and dispatch requirements were met.

HOWEVER, such [lack of] limitations are operator-specific, per OpSpec B039:

Quote:

c. Minimum Navigation Performance Capability Required. The certificate holder shall not conduct any operation in NAT/MNPS Airspace unless the certificate holder has satisfactorily demonstrated that the navigation equipment is installed and operational on any airplane used in NAT/MNPS operations. The procedures for use of this equipment must meet the following NAT/MNPS requirements on a continuing basis:
(1) The standard deviation (one sigma) of the lateral tracking error is less than 6.3 nautical miles (NM).
(2) The proportion of the total flight time in NAT/MNPS Airspace spent by aircraft 30 NM or more off the exact centerline of the assigned track is less than 5.3 x 10E-4 (less than one hour in 1,887 flight hours).
(3) The proportion of the total flight time in NAT/MNPS Airspace spent by aircraft between 50 and 70 NM offtrack is less than 1.3 x 10E-4 (less than one hour in 7,693 flight hours).
(4) Suitable displays must be available at each pilot's station to permit continuous monitoring of the long-range navigation systems cross-track and along-track information.

The 744 DDG simply refers to the FCOM Limitations section for Dispatch and entry requirements. Again, no specific time limitations for degraded systems AFTER entry.

Quote:

Originally Posted by felixthecat (Post 9435282)

NEWYEAR quoted this a while back

What aircraft is this for, and if not aircraft specific where do you find these details? Never seem them in the 777 FCOM or other documents.

I'm happy enough that on a 777 the loss of both FMC really isn't that big a deal since the CDUs have the current route and any arrival already programmed in their memory, plus ALT NAV lets you program via LAT/LONG. Positional info now just via ADIRU, and slowly degrades over time when out of nav beacon range.

Check your 777 MEL under FMC and you might find the same or similar numbers to what is posted above. Also, any plans ahead of time for flap maneuver speeds, go-around N1, etc. How about all those gaps that may be visible between some of the waypoints in the STAR? Any plans ahead of time if ATC gives a different STAR? There are a few things to plan for ahead of time.

Any other considerations to think of? And thoughts?

Other than:
1) Vref Speeds
2) Flaps Man speed
3) Fuel situation
4) When to descend?

A lot depends on when/where the double FMGS failure occurs on a small bus. Flying diagonally across the corner of a Jepp charts, outside radar coverage in a busy area with a frequency change was interesting. Immediate hand flying meant other pilot had hands full looking for onward chart corner, then manually tuning navaids. After that I got extra charts that they could be pre-folded at such diagonal chart corner crossings.