Hi everyone,

 

Currently doing flights high up in the north of Canada, where one of the approach plates shows to reference true north.

I know that the 747 has a switch to change from magnetic to true heading but I can't find such one on the 737.

I have searched the FCOM vol 1 and 2 which only states how the diiference between TRUE and MAGNETIC are represented on the different displays.

 

I looked here in the forum but got only 1 outdated topic which didn't cover my question.

Also looked around the cockpit but have no clue where to find this switch

 

So, does anyone knows how to switch from MAGNETIC to a TRUE heading with the 737 ?

(have not checked FMS yet)

 

Thanks for helping out.

 

Dieter

how to switch from MAGNETIC to a TRUE heading with the 737 ?

 

I think it automatically switches.

Hi Dieter and Kenny,

I think that simply your B737 cannot operate at that latitude: from page 53 1st volume of b737 manual (limitations):

"Maximum flight operating latitude – 82° North and 82° South, except for the region between 80° West and 130 ° West longitude, the maximum flight operating latitude is 70° North, and the region between 120° East and 160° East longitude, the maximum flight operating latitude is 60° South."

So (apart maybe some specifically equpped version) this bird is not built to operate in those regions...

 

Anyway remember first rule: studying the manuals ia paramount

Ciao

Andrea Buono

I think that simply your B737 cannot operate at that latitude

 

It can with polar navigation option. Ryan told that this wouldn't be included in the NGX.

 

Where this switch can be - http://forum.avsim.net/topic/346400-northernpolar-operations/page__st__25#entry2111968.

 

Meese shoot.

 

Tnx for all replies.

Learned something new.

NUTS!! Man, this can impact on my operations (very good question by the way). Anyone (RW or virtual) operating in northern Canada, Norway, Iceland, Greenland, Russia, would be routinely operating higher than 70* N. In case anyone thinks that very rarely happens, I saw 5 737's operating north of 60* at one time in a "snapshot" on Flight Aware this afternoon. It's not at all uncommon, and when I lived in the north, would see 737's and 727's all the time up there. We'll have to look at this and possibly make alternate plans for our routing. Thanks to the OP for this.

Andrea was right though... "Our" 737 (as in, the NGX) would not be legally allowed to operate up North. PMDG decided not to model this, probably because of the extra work involved to get it right, and the small user-group interested in it.

Yeah, and in reality, given that isogonic lines wander all over the place and the whole reason for using True North is because the variation changes so rapidly over a short distance, it would probably be a nightmare to code, if it's even possible.

I've done Barrow and many times. Not a big deal without the special gear.

 

I've done Barrow and many times. Not a big deal without the special gear.

On second thought, I've never been to a field where they had True runways. Maybe it does get goofier.

Yeah, where they use magnetic headings, you use magnetic. The thing is when you get far enough north, the variation is so far off true north, and varies greatly over such a short distance, that trying to use magnetic headings becomes a bit of a crap shoot. I've flown in areas where variation runs from 30 degrees to 60 degrees off in a very short distance. I did not have a T/N switch obviously on the 185, so at some point you just line yourself up with something that's reasonably straight and set your gyro compass to what you figure the true heading is and go with that. Obviously that's a LOT riskier if you are trying to do an NDB approach to 500 & 1 on a gravel strip in the far north where your variation might change 1 or 2 degrees while on final. There's a reason they call it the "area of compass unreliability" :smile:. The other thing too is that your magnetic compass is at a pretty fair tilt even in level flight because north is no longer way beyond the horizon. It's as much below you as in front of you. So that tends to pull the compass down which also makes it harder to read as it bounces around. I never noticed that being a problem and it's likely not an issue with a fully slaved system as you get on the airliners though.