Mag vs True on NATs

[767-300ER]

Would PPrune members be willing to tell me their company and fleet type and whether or not they use Mag or True on the North Atlantic, please?

Thanks very much....


767-300ER

[ETOPS]

On all our fleets, 767/777/747, it's standard procedure to use true. This is because the North Atlantic is "scheduled" airspace and thus it's a requirement. Check in your flight guide (Aerad or similar) for the other "scheduled areas" - might come as a suprise.......

[GlueBall]

We don't fly the crossing in Heading mode. We fly the assigned TRACK coupled via INS or GPS and for that matter it's inconsequential whether your HSI "compass card" is selected to MAG or TRUE.

[Semaphore Sam]

On plotting chart, there is a section which, for every 10 degrees east-west of passage, you can plug in the north or south coordinates (ie, 54N to 52N), and get a distance and initial course. This allows for checking accuracy of programmed waypoints; gross errors become obvious (I've found some potential gross errors this way, due to finger blips, and one actual data base mistake). This course data uses True; thus, to access this info, True info must be used (changeable mag variation is thus not a factor). Also, True course plots are much easier to see on the chart. My company, upon entering Oceanic Areas, changes to True, as policy...a good one, in my opinion. As for fleet, I was 747 classic & 400, just graduated to Falcon 900, and use this aid regardless of fleet.

[None]

ETOPS wrote: "This is because the North Atlantic is "scheduled" airspace and thus it's a requirement."


Can you expand on this please?

[Intruder]

742 and 744: Magnetic.

The NAT system is well south of the AMU (Area of Magnetic Unreliability).

However, when going Europe - ANC, True tracks are used in northern Canada airspace.

[no sig]

http://www.nat-pco.org/mnpsa.htm

on the iCAO website has the manuals if you need them.

[GlueBall]

Semaphore Sam says: "...On plotting chart, there is a section which, for every 10 degrees east-west of passage, you can plug in the north or south coordinates (ie, 54N to 52N), and get a distance and initial course. This allows for checking accuracy of programmed waypoints; gross errors become obvious..."

Are you an old Navigator who brings along one historic CR6 whiz-wheel and plotter and actually dabbles with True course, drift and distance between wayponts?

When we fly an assigned Track we keep it simple: We don't make a mountain out of a molehill. We only connect the waypoints on a plotting chart with a pen or pencil. Then we periodically double check our position by pushing "Hold" on the individual INS or GPS units...which normally are triple-mixed into the FMS...which is coupled to one of the Auto Pilots. We are only concerned with our actual position relative to our assigned Track. We don't get creative about Variation and about comparing TRUE versus MAG values. And during a crossing I actually spend more time reading popular magazines. Yawn.

[411A]

Have to agree with Glueball here, it really makes no difference, true or mag, using INS/IRS equipment.
Now, on the other hand, if we were doing pressure pattern or grid navigation in the rather far north....

[Semaphore Sam]

Glueball & 411A;
I understand what you're saying...but, one more crosscheck of serial waypoints using course & distance might just find a programming error. This technique is useful before entering the NATS, and ESPECIALLY when a change of waypoints is assigned enroute; not to crosscheck position, but to find programming errors. To check 4 or 5 waypoints takes less than 3 minutes. Maybe a certain Delta flight might have found this useful...

Now, back to my enroute Playboy (except with distaff F/O).