North Atlantic Contingency Manoeuvre

[pilothouse]

Hello.

I'm sure I've read somewhere that the North Atlantic Contingency Manoeuvre is changing wef 16th February 2006, with the parallel track moving from 30nm to a 15nm offset from the planned track.

Can anyone shed any light on this, please?

[mr ripley]

All details are at http://www.nat-pco.org/
Regards

[pilothouse]

Thank you Nr Ripley, I now recognise it as where I read it.

But how come there seems to be nothing else - nothing on NATS, CAA, etc?

Have longhaul aircrew been alerted to this?

[srjumbo]

Yes, longhaul crew have.

[PPRuNe Radar]

Q)EGGX/QAOXX/IV/NBO/E/000/999/5216N01949W639
FROM 06/02/16 00:01 TO PERM G0021/06

E)IN FLT CONTINGENCY PROC FOR NORTH ALTANTIC REGION CHANGE. CONTINGENCY OFFSET DIST CHANGED TO 15NM AND CONTINGENCY OFFSET ALT CHANGED TO CLIMB OR DECEND 500FT FOR ALL FLT LVL.

FULL DETAILS CONTAINED IN REGIONAL SUPPLEMENTARY PROC (ICAO DOC 7030) AND AMDT TO ENR 2-2-4-12/13 TO BE PUBLISHED AT AIRAC 4/2006.

Canada have published the AIC for the NAT Region, ICAO is publishing the full procedure in DOC 7030, and anyone keeping their UK AIP up to date should pick this up with the amendment covering AIRAC cycle 4 in April :ok:

[Bird On]

Thanks for the heads up on this.
Haven't come across any advance info from my company as yet.
Cheers.

[Captain Airclues]

Do the people who write these procedures ever try them out on a simulator?
The nat-pco site says that it might be necessary to overshoot the new track when establishing a reciprocal track. However, it still insists that we turn through ninety degrees while establishing a parallel track in the same direction. A 180 degree turn actually causes less of an offset than two 90 degree turns, due to the time taken to reverse the turn. In the simulator a few nights ago we did a 90 degree turn to establish on an offset in the same direction at FL350 and Mach .85. The aircraft deviated 28.4 miles from the original track.
The 90 degree turn technique worked perfectly when we were trying to achieve a 30nm offset, but not with a 15nm offset. I suggest that the procedure should be change to either;
1. If requiring to establish an offset on a reciprocal track then turn through 180 degrees and then continue the turn to achieve the 15nm offset as soon as possible.
2. If requiring to establish an offset on a track in the same direction then turn through 60 degrees and then reverse the turn so as to achieve a 15nm offset.
The 60 degree method gets the aircraft to 7.5nm from the original track (half way between the tracks) in exactly the same time as the 90 degree method, but avoids overshooting the required track. Obviously with the 180 degree turn there is no alternative to slightly overshootong the new track (by about 7nm) but why write a technique that guarantees a large overshoot when there is a much easier alternative?
Airclues

[stilton]

We have been wondering the same thing.

Anyone know why the change to 15 miles?

[CONF iture]

... next step could be 30NM separation between the tracks ...

[stilton]

That seems logical and quite likely an attempt to improve capacity within the current dimensions of the Track structure I suppose.

Does not seem like a good idea though, with dubious separation during contingency manoeuvres.

[NorskAir]

I heard the reason it changed to 15nm FROM 30nm is 9/11, on 9/11 several aircraft diverted using an offset, some of these aircraft came dangerously close in the middle. 15NM will give a buffer between the tracks.

[You Gimboid]

CONF_iture sounds more likely to me - first RVSM, then 8 NAT tracks each way by next summer, you mark my words..!

[NG_Kaptain]

Does anyone have info on its effectivity when flying random track routes vs NAT tracks?

[18Holes]

Do the people who write these procedures ever try them out on a simulator?
The nat-pco site says that it might be necessary to overshoot the new track when establishing a reciprocal track. However, it still insists that we turn through ninety degrees while establishing a parallel track in the same direction. A 180 degree turn actually causes less of an offset than two 90 degree turns, due to the time taken to reverse the turn. In the simulator a few nights ago we did a 90 degree turn to establish on an offset in the same direction at FL350 and Mach .85. The aircraft deviated 28.4 miles from the original track.
The 90 degree turn technique worked perfectly when we were trying to achieve a 30nm offset, but not with a 15nm offset. I suggest that the procedure should be change to either;
1. If requiring to establish an offset on a reciprocal track then turn through 180 degrees and then continue the turn to achieve the 15nm offset as soon as possible.
2. If requiring to establish an offset on a track in the same direction then turn through 60 degrees and then reverse the turn so as to achieve a 15nm offset.
The 60 degree method gets the aircraft to 7.5nm from the original track (half way between the tracks) in exactly the same time as the 90 degree method, but avoids overshooting the required track. Obviously with the 180 degree turn there is no alternative to slightly overshootong the new track (by about 7nm) but why write a technique that guarantees a large overshoot when there is a much easier alternative?
Airclues

Your alternate might not be behind at all times. Sometimes it might be necessary to turn 90° let's say left, and then 90° right, asssuming your alternate is off at your 10 'o clock.

[CONF iture]

Does anyone have info on its effectivity when flying random track routes vs NAT tracks?
According to http://www.nat-pco.org/nat/MNPSA/MNPSA_2005.pdf, it's valid for the all NAT MNPS Airspace.


Your alternate might not be behind at all times. Sometimes it might be necessary to turn 90° let's say left, and then 90° right, asssuming your alternate is off at your 10 'o clock.
You did quote Mr Airclues but you didn't read it with attention, and what he said makes a lot of sence.

[18Holes]

According to http://www.nat-pco.org/nat/MNPSA/MNPSA_2005.pdf, it's valid for the all NAT MNPS Airspace.



You did quote Mr Airclues but you didn't read it with attention, and what he said makes a lot of sence.

Sorry for not having read carefully, but still, even though I agree with him on the principle, what if you caught cargo fire and your alternate is not behind? Still mind of making a perfect 15 nm offset? As I said, I agree on the principle, but at that stage my goal is to bring her down ASAP, so, paying the due attention, I personally agree with the procedure now in effect.

[Captain Airclues]

18Holes

We are not talking about an emergency diversion to an alternate, we are talking about the North Atlantic Contingency Manoeuvre, where the aim is to establish on a track offset by 15 miles. If you intend to establish on a reciprocal track then you have no alternative but to overshoot the track. However if you intend to establish on a parallel track in the same direction, then why overshoot it when it is not necessary. A turn though 60 degrees followed by 60 degrees the other way rolls out exactly on the 15 mile offset (I've tried it on the sim). Why insist on a 90 degree turn which overshoots the offset by some 13 miles?

Airclues

[18Holes]

18Holes

We are not talking about an emergency diversion to an alternate, we are talking about the North Atlantic Contingency Manoeuvre, where the aim is to establish on a track offset by 15 miles. If you intend to establish on a reciprocal track then you have no alternative but to overshoot the track. However if you intend to establish on a parallel track in the same direction, then why overshoot it when it is not necessary. A turn though 60 degrees followed by 60 degrees the other way rolls out exactly on the 15 mile offset (I've tried it on the sim). Why insist on a 90 degree turn which overshoots the offset by some 13 miles?

Airclues

I completely agree with you. My comment was on what is written in the procedure (90°)