NAT pos'n reprorts. Mag or true winds?
Thread Starter
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.
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.
Thread Starter
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?
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?
Warning Toxic!
Disgusted of Tunbridge
Disgusted of Tunbridge
Join Date: Jan 2005
Location: Hampshire, UK
Posts: 4,011
Likes: 0
Received 0 Likes
on
0 Posts
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.
Thread Starter
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.
Also, is there any ref that I can quote for this?
Thanks.
Join Date: Mar 2000
Location: Arizona USA
Posts: 8,571
Likes: 0
Received 0 Likes
on
0 Posts
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"?
Older is better...
Join Date: Dec 2000
Location: on the golf course (Covid permitting)
Posts: 2,131
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
Thread Starter
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.
Problem solved, then. Report Oceanic winds in degrees TRUE.
Mind you, it might have been NUTS.
Problem solved, then. Report Oceanic winds in degrees TRUE.
Join Date: Mar 2000
Location: Arizona USA
Posts: 8,571
Likes: 0
Received 0 Likes
on
0 Posts
Our UNS-1K displays xxxT/xx, so it's True winds.
As far as I know, the only Mag wind data is at aerodromes.
As far as I know, the only Mag wind data is at aerodromes.
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.
Join Date: Jul 2000
Location: West
Posts: 399
Likes: 0
Received 0 Likes
on
0 Posts
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.
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.
Thread Starter
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.
