Board index FlightGear Support Flying

Odd Behaviour

Controlling your aircraft, using the autopilot etc.

Odd Behaviour

Postby Robertfm » Fri Dec 03, 2021 1:00 pm

I am flying KJFK to KELM I am on auto pilot and according to the route manager the track is 305 Degrees. The plane is following the Phi track on the map however all the instruments in plane and on my Free Air Map are showing a track of 318. Any suggestions. I am flying my usual PA28 Warrior.

When I was lined up on the runway it showed 301 degrees which is correct. Any suggestions.
Robertfm
 
Posts: 1721
Joined: Thu Apr 25, 2019 5:56 pm
Callsign: RFM1
Version: 2020.3.11
OS: W10 v 19041.746

Re: Odd Behaviour

Postby wkitty42 » Fri Dec 03, 2021 2:25 pm

an initial eWAG: sounds like magnetic deviation difference...
"You get more air close to the ground," said Angalo. "I read that in a book. You get lots of air low down, and not much when you go up."
"Why not?" said Gurder.
"Dunno. It's frightened of heights, I guess."
User avatar
wkitty42
 
Posts: 9146
Joined: Fri Feb 20, 2015 4:46 pm
Location: central NC, USA
Callsign: wk42
Version: git next
OS: Kubuntu 20.04

Re: Odd Behaviour

Postby Robertfm » Fri Dec 03, 2021 2:47 pm

I have flown in US numerous times and never noticed it. in Canada it's 8 degrees
Robertfm
 
Posts: 1721
Joined: Thu Apr 25, 2019 5:56 pm
Callsign: RFM1
Version: 2020.3.11
OS: W10 v 19041.746

Re: Odd Behaviour

Postby MariuszXC » Fri Dec 03, 2021 5:49 pm

Robertfm wrote in Fri Dec 03, 2021 2:47 pm:I have flown in US numerous times and never noticed it. in Canada it's 8 degrees


Wkitty mentioned deviation, not variation.
They are not the same.
Variation is a property of a geographical area, experienced by everything in that area.
Deviation is unique to an aircraft (or a boat, car, etc..) and depends on magnetic fields / field distortions created by other equipment.

Try the same route in a different aircraft and compare?
INOP
MariuszXC
 
Posts: 1061
Joined: Tue May 18, 2021 5:38 pm
Location: Europe
Callsign: SP-MRM
Version: 2020.4
OS: Ubuntu 16.04

Re: Odd Behaviour

Postby Maerchenprinz » Fri Dec 03, 2021 6:17 pm

A quick internet search shows -12(W) for KELM resp. -14deg variation for KJFK; Some route managers calculate magnetic, some true headings, so you may want to check that first.
Fun fact for the weekend: Some airports way up north in Canada and elsewhere may have a magnetic variation of up to 70deg or an annual variation in variation of up to 70deg. Their runway designator will then be the true heading with an additional "T" for true.

Ciao,

Adrian
User avatar
Maerchenprinz
 
Posts: 306
Joined: Thu Mar 15, 2007 6:24 pm
Location: Bochum, it's better, much better than you think!
Callsign: Adrian

Re: Odd Behaviour

Postby I-PIC68 » Fri Dec 03, 2021 7:24 pm

Aircraft: Boeing 777-300ER, Airbus A320, Cessna 172P, DHC-6
Airport: LIPQ, LGTS
User avatar
I-PIC68
 
Posts: 97
Joined: Sun May 24, 2020 10:16 am
Location: Trieste, Italy
Callsign: I-PIC68
Version: 2020.3.19
OS: Windows 10

Re: Odd Behaviour

Postby Robertfm » Fri Dec 03, 2021 7:48 pm

Thank you for all the information. All I can say is I have never noticed these variations when previously flying in the US but have noticed flying in Canada and it does warn of this on various charts. When I switch from magnetic to true there only seems to be a 4 degree variation but as described above the variation is up to 14 degrees. I will study the information
Robertfm
 
Posts: 1721
Joined: Thu Apr 25, 2019 5:56 pm
Callsign: RFM1
Version: 2020.3.11
OS: W10 v 19041.746

Re: Odd Behaviour

Postby WoodSTokk » Sun Dec 05, 2021 8:33 pm

You can see the variation in FG by checking the property '/environment/magnetic-variation-deg'.
On KJFK i have around -12.9° and on KELM around -11.6°.
This will not match the magnetic field today, because the magnetic field information in FG is outdated.
The difference to your 15° is maybe that your horizontal gyro was drifted a bit away.
WoodSTokk
 
Posts: 1077
Joined: Tue Oct 17, 2017 3:30 pm
Location: Milky Way/Sol/Earth/Europe
Callsign: SX-W57
IRC name: WoodSTokk
Version: 2020.4.0
OS: Debian Bullseye

Re: Odd Behaviour

Postby Robertfm » Sun Dec 05, 2021 8:43 pm

Thanks. I was flying further south yesterday and getting no variations,
Robertfm
 
Posts: 1721
Joined: Thu Apr 25, 2019 5:56 pm
Callsign: RFM1
Version: 2020.3.11
OS: W10 v 19041.746


Return to Flying

Who is online

Users browsing this forum: No registered users and 8 guests