Do you fly constant MACH on the NAT Tracks?
04-14-2014, 04:38 AM
#1
Gets Weekends Off
Thread Starter
Joined APC: Sep 2010
Position: EWR 777 Captain
Posts: 1,715
Do you fly constant MACH on the NAT Tracks?
So as part of merging 2 legacy carriers the inevitable issues arise regarding procedures that differ. I have involved myself in a debate regarding a procedure that came from the "other" side of the 767 fleet. In particular we are now instructed by our flight manual to fly the tracks using FMC ECON mode and altering the Cost Index as we go to maintain a constant mach. Paragraph 7.3.4 of the North Atlantic Operations and Airspace Manual strictly forbids this practice, but the company response is that our FAA Primary Operations Inspector (POI) approved this procedure and therefore it is legal. I have written to ALPA and the company complaining that unless we have a written waiver from the NAT TRACK authorities then the POI does not have the authority to supersede paragraph 7.3.4. Previous policy on my fleet was simple: Fly the tracks with a hard coded mach as required. The other sides theory is that using Cost Index saves fuel because the throttle response and recommended altitudes are better when the FMC uses ECON mode as compared to when the FMC is hard coded with a speed.
Question: Do other companies fly the tracks using ECON Mode and then adjust Cost Index to try and maintain a constant mach?
Question: Do other companies fly the tracks using ECON Mode and then adjust Cost Index to try and maintain a constant mach?
7.3.4 In the application of Mach Number Technique, pilots must adhere strictly to their assigned True Mach Numbers unless a specific re-clearance is obtained from the appropriate ATC unit. However, as the aircraft weight reduces it may be more fuel efficient to adjust the Mach Number. Since the in-trail and crossing track separations between individual aircraft are established on the basis of ETAs passed to, or calculated by, ATC, it is essential that ATC approval is requested prior to effecting any change in cruise Mach Number. Such approval will be given if traffic conditions permit. Pilots must recognise that adherence to the assigned Mach Number is essential. No tolerance is provided for. Pilots must not utilise Long Range Cruise or ECON FMC modes when transiting NAT MNPS airspace. If an immediate temporary change in the Mach Number is essential, e.g. due to turbulence, ATC must be notified as soon as possible. Pilots with experience of flying in oceanic airspaces other than the North Atlantic, may be familiar with a procedure in those areas which permits pilots to unilaterally elect to change their cruising mach number by up to 0.02M, without prior ATC approval. This is not the case in the North Atlantic MNPS airspace.
04-14-2014, 04:45 AM
#2
Can't abide NAI
Joined APC: Jun 2007
Position: Douglas Aerospace post production Flight Test & Work Around Engineering bulletin dissembler
Posts: 11,989
You are supposed to ask for a re-clearance when you need to adjust for weight, winds, etc ... but many don't.
I see the operator's idea, but planning so close to max efficiency isn't particularly realistic. What's .005 of a Mach when you're 3,000 feet below optimum altitude?
I see the operator's idea, but planning so close to max efficiency isn't particularly realistic. What's .005 of a Mach when you're 3,000 feet below optimum altitude?
Last edited by Bucking Bar; 04-14-2014 at 04:56 AM.
04-14-2014, 04:59 AM
#4
Can't abide NAI
Joined APC: Jun 2007
Position: Douglas Aerospace post production Flight Test & Work Around Engineering bulletin dissembler
Posts: 11,989
Maddox max is obviously right. Some play with the CI, most just over write it.
On an MD88, my guess is you would have to turn off the autothrottles and autopilot to fly a constant anything.
On an MD88, my guess is you would have to turn off the autothrottles and autopilot to fly a constant anything.
04-14-2014, 05:07 AM
#5
Gets Weekends Off
Thread Starter
Joined APC: Sep 2010
Position: EWR 777 Captain
Posts: 1,715
Originally Posted by maddogmax
You fly your assigned Mach number. It doesn't matter how you do it as long as you do it.
I'm afraid I disagree. Did you read the above regulation? "Pilots must not use Long Range Cruise or ECON modes" "NO tolerance is provided for".
.815 is not the same as .810 and the regulations specifically tell the pilot that use of ECON mode is prohibited even if they are maintaining a constant mach. I'm not sure how much more obvious the regulation can be.
04-14-2014, 05:14 AM
#6
Can't abide NAI
Joined APC: Jun 2007
Position: Douglas Aerospace post production Flight Test & Work Around Engineering bulletin dissembler
Posts: 11,989
Originally Posted by Sunvox
I'm afraid I disagree. Did you read the above regulation? "Pilots must not use Long Range Cruise or ECON modes" "NO tolerance is provided for".
Our Lasagne tends to be soggy. The chicken and steak are great though!
04-14-2014, 05:21 AM
#7
Gets Weekends Off
Joined APC: Feb 2006
Posts: 1,242
Originally Posted by Sunvox
I'm afraid I disagree. Did you read the above regulation? "Pilots must not use Long Range Cruise or ECON modes" "NO tolerance is provided for".
.815 is not the same as .810 and the regulations specifically tell the pilot that use of ECON mode is prohibited even if they are maintaining a constant mach. I'm not sure how much more obvious the regulation can be.
.815 is not the same as .810 and the regulations specifically tell the pilot that use of ECON mode is prohibited even if they are maintaining a constant mach. I'm not sure how much more obvious the regulation can be.
04-14-2014, 06:14 AM
#9
Gets Weekends Off
Joined APC: Feb 2006
Posts: 1,242
To be more specific, there are different ways to fly a constant Mach. I would think staying in ECON or LRC and playing with the CI would be a pain and not very accurate. At NWA/DAL we ALWAYS hard tune the assigned Mach number in the FMC while on the tracks. Hope that answers your question.
04-14-2014, 06:19 AM
#10
Gets Weekends Off
Joined APC: Jun 2008
Position: 737 CAPT
Posts: 1,882
Originally Posted by Sunvox
So as part of merging 2 legacy carriers the inevitable issues arise regarding procedures that differ. I have involved myself in a debate regarding a procedure that came from the "other" side of the 767 fleet. In particular we are now instructed by our flight manual to fly the tracks using FMC ECON mode and altering the Cost Index as we go to maintain a constant mach. Paragraph 7.3.4 of the North Atlantic Operations and Airspace Manual strictly forbids this practice, but the company response is that our FAA Primary Operations Inspector (POI) approved this procedure and therefore it is legal. I have written to ALPA and the company complaining that unless we have a written waiver from the NAT TRACK authorities then the POI does not have the authority to supersede paragraph 7.3.4. Previous policy on my fleet was simple: Fly the tracks with a hard coded mach as required. The other sides theory is that using Cost Index saves fuel because the throttle response and recommended altitudes are better when the FMC uses ECON mode as compared to when the FMC is hard coded with a speed.
Question: Do other companies fly the tracks using ECON Mode and then adjust Cost Index to try and maintain a constant mach?
Question: Do other companies fly the tracks using ECON Mode and then adjust Cost Index to try and maintain a constant mach?
Thread
Thread Starter
Forum
Replies
Last Post
captain_drew
Flight Schools and Training
38
12-05-2012 08:29 AM
