NAT pos'n reprorts. Mag or true winds?
 

Our FMCs (767 Pegasus) give magnetic winds on the position reoport page but it got me wondering what you use in an oceanic position report since there is such a large variation in...well...variation up near the Canadian coast. Reporting it in the wrong format would screw the plotting charts!
According to the NAT/Oceanic rules, do you report the magnetic or true wind? I couldn't find the answer in any company books or in our copy of the NAT FAA manual.

Thanks.

FMC displays Magnetic whilst the map displays True wind, so it isn't that hard to move your eyes a few inches to read off the wind from somewhere else.

Would Boeing specify magnetic wind on the FMC for any specific reason? Not much use for plotting on a chart and the variation may well be adrift if the database of variation hasn't been changed (according to our engineering dept). I draw a TRUE wind arrow on the plotting chart at each waypoint since it makes the drift appear more sensible, if you see what I mean.

So, regardless of what is usually done, what is the correct method that should be used?

Sorry, I inadvertently misled you. One reads off the map display the wind vector which is right in front of you, not off the actual CDU. I assume the meteorologists make an automatic correction.

OK. It makes sense to call out the true wind so that it can be used for plotting. The next question is "why does the FMC not give the true wind on the POSN RPT page"?

Also, is there any ref that I can quote for this?

Thanks.

Can't help you there with modern FMC,'s however...the 'ole Hamilton Sunstrand FMC on the Lockheed tri-motor would give you mag or true winds, with just a push of one switchlight, IE: displayed either way you desire.

Older is better...:}

On the B747-400 the 'True/Magnetic' reference switch determines how all systems display the wind. So, with the switch in 'True', the PFD, ND, RDMI and FMC all report wind in degrees True.

The means that the Pos Report page gives the ATC data in the required format and you just have to read it out to them. The one thing it doesn't do is store the mid point data though.

Wifey reports a phonecall from "NUTS" (a soft-porn mag in the UK) asking her to tell me they want a report in TRUE WIND. I'm assuming it was NATS, not NUTS.

Mind you, it might have been NUTS.:O

Problem solved, then. Report Oceanic winds in degrees TRUE.

Our UNS-1K displays xxxT/xx, so it's True winds.
As far as I know, the only Mag wind data is at aerodromes.

Our UNS-1M does likewise.
And, our Honeywell HT9100...and the Hamilton Sundstrand FMS (original fit, circa 1977).
Get a grip, folks...winds aloft are TRUE, at the airport, magnetic (normally).
Rocket sceince it ain't...despite what some 'new' pilots think.:rolleyes::rolleyes:

Pegasus FMC Position Rpt Page Wind is True
 

I fly the 767 with a Pegasus FMS.

The Boeing Volume II states the wind on the position report page is in true:

4 Temperature and Wind (TEMP WIND)
TEMP displays the OAT in degrees C.
WIND displays the wind direction and speed. Wind direction is shown in degrees true.

Our Pegasus FMCs display mag on the position report, hence the original post. It might have been an error in pin selection? The engineers have now been informed.

777 position report page in °T, ND in °M. ICAO Position Rep should be in °T, hence the use of True oj the positin rep page.

The MD11 wind display is always TRUE regardless from the true/mag setting of the Navigation display. So all reports are done with true wind values.