Emergency offsetting in the NAT tracks
 

Years ago when I few the north atlantic, I believe the emergency procedure to descend withing the track structure was to acquire a distance of 30 nm offset. Now if I understand correctly, it has changed to 15 nm. Seeing as the tracks are still 60 miles apart, can anyone come up with the reason for making the distance 15 nm vice 30 nm?

Or, am I out to lunch on this?

Yes, here's one reason - old system, westbound tracks: Aircraft on track B has a problem and crew decide to offset 30 left, meanwhile another aircraft on track C has a problem and crew decide to offset 30 right....and..........:ooh:

( Sounds unlikely but AFAIK the change came out in the wash up of events on the NATS during 9/11)

thanks wiggy. that makes a lot of sense for weather diversions, and for that reason aircraft are to climb/descend 300 feet depending on track, and thus avoiding other aircraft doing the same. After all, if weather affects one aircraft, it's likely to affect others.

An engine failure seems to be a totally different animal. Not a short term diversion, but perhaps an hour or two of flying where posssibly another aircraft is within 15 miles (plus or minus) plus 500 feet altitude difference. I'm just surprised it isn't 30 miles for an engine failure, that's all.

30 miles seemed to work before....

Or is it in preparation to later set the tracks 30 miles apart ... ?

Do we know how many aircrafts about turned back to Europe on that day ?
Must have been a real nightmare on Shanwick HF ...

Did any turn back or were they all routed and landed in Canada if they were already in the air?

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Probably when it was obvious that the US access was not possible anymore, many who were in a position to go back to the departure airport did. Shanwick Oceanic should be able to tell.

Wiggy is right, can't see the complication here. If the separation between tracks became 30nm, 15nm would cause the same issue with multiple offset a/c.

OAP