Dual fmc failure
Joined: Apr 2008
Posts: 1
Likes: 2
From: nowhere
Gee, I wonder if I would be asking for a reference/link if I knew where it was.
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.
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.
Joined: Aug 2005
Posts: 257
Likes: 4
From: ME
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.
Cessna-320.
Joined: Jan 2014
Posts: 720
Likes: 1
From: N5109.2W10.5
Of course ATC had no idea.
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."
Joined: Apr 2010
Posts: 1,319
Likes: 100
From: IRS NAV ONLY
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.
Joined: Mar 2007
Posts: 502
Likes: 0
From: Up North….
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.
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
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.
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.
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
Joined: May 2000
Posts: 3,203
Likes: 2
From: Seattle
For the 744 (from our FCOM):
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:
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.
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.
requirements as the sole means of navigation for flights up to 18 hours duration.
HOWEVER, such [lack of] limitations are operator-specific, per OpSpec B039:
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.
(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.
Last edited by Intruder; 11th July 2016 at 19:23.
Joined: Apr 2008
Posts: 1
Likes: 2
From: nowhere
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.
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.
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.
Joined: Jun 1999
Posts: 408
Likes: 0
From: Queensland
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.
