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What "heading" modern jet use?

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What "heading" modern jet use?

Old 2nd Sep 2015, 04:05
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What "heading" modern jet use?

I mean what does the heading refer to on the primary flight display on modern jets?

Magnetic heading?

And what "heading" pilots will come across as regard to the whole flight?

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Old 2nd Sep 2015, 04:09
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The answer to your question is yes.
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Old 2nd Sep 2015, 04:25
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Display: Magnetic (except in Polar/AMU areas).

Source: TRUE heading from IRS, +/- MagVar based on GPS/IRS position.
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Old 2nd Sep 2015, 08:24
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What "heading" modern jet use?

Edited; it's indeed of course magnetic track up on the ND as customer option, tnx 737Aviator.

Last edited by JeroenC; 8th Sep 2015 at 21:50.
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Old 2nd Sep 2015, 08:57
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on the Navigation Display of the 737NG it's a customer option, True hdg in our case.
Magnetic Track you mean? Even with the track up ND option, the heading on the MCP, bottom of the PFD, etc is all Magnetic. Imagine ATC asking you to fly a heading and you start flying true headings!
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Old 3rd Sep 2015, 06:03
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Let say we fly from HK to JFK, how do we make use of magnetic heading? Does the magnetic heading thing will or have to adjust itself from time to time in different location?
I'm a bit confused
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Old 3rd Sep 2015, 06:46
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I'm a bit confused
TBH it sounds to me a little bit like you're "trying to run before you can walk"....but I'll give I'll it go.


Use Tokyo NRT (RJAA) to JFK (KJFK) as an example (rather than HK, simply avoid the north pole..) if you want to fly the shortest route, a great circle track, you'll probably start off heading north east, as you progress the heading will become east, then in the later stages of the flight south easterly, so yes, the required heading is changing throughout the flight.

Great Circle Mapper


I hesitate to go into specialist navigator territory but I think in the "old" days of plotting charts and plotting routes by hand the way you would fly this is by breaking the very long route down on your chart into a series of shorter sections (e.g every crossing of intervals of 1 or 2 or 5 degrees of longitude) measuring the initial heading for each section of the chart, (true heading) and then derive the magnetic heading (from the chart/tables) and writing it down so that you knew what heading to fly on your magnetic compass.... If you then went off and actually flew the whole thing, steering the aircraft using the heading selector you would indeed have to adjust your heading as you progressed along the route - every time you'd established you'd flown another of your 1/2/5 degrees of longitude defined sections as used in planning you'd have to tweak the heading knob to required number you'd written down.

Nowadays we generally don't do that.....an aircraft flying a route "coupled" to GPS and/or Inertial navigation should in theory follow the great circle route between two consecutive loaded waypoints (e.g RJAA to KJFK) as if on rails, without any pilot steering inputs from the flight deck. What we do do is monitor the heading changes en-route to ensure correct navigation, rather than inputting the heading change ourselves. Whether we are looking at a magnetic or true heading depends mainly on pilot selection, though it's usually True heading at High latitudes.

I hasten to add in the real world we'd probably not be flying a 5000 mile plus direct great circle route, due to airspace restriction, weather, etc....


Hope that makes sense...to someone....anyone

Edit to add for the purists: Given the context I'm invoking the KISS principle, ignoring wind, assuming heading=track)

Last edited by wiggy; 3rd Sep 2015 at 10:56.
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Old 3rd Sep 2015, 21:20
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Let say we fly from HK to JFK, how do we make use of magnetic heading? Does the magnetic heading thing will or have to adjust itself from time to time in different location?
As long as the IRS and FMS are operating properly, the magnetic variation will be input into the system and the display adjusted continuously and automatically.
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Old 7th Sep 2015, 07:34
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My pleasure, you're welcome
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