Hi all from northern germany,

yesterday i take my old polar crossing chart and simulate a polar flight with the

wounderfull PMDG777 from ENVA to PANC. Thanks Team from PMDG!!!

the route was: PANC GISOX N70E007 N76W000 N82W020 N85W060 N84W090 N80W130 N74W141

N70W146 TKA Panc.and no winds clear skys.

the flight endet with no FScrash.

when passing GISOX i change to the TRUE heading.

after N70EW007 the GRID sign comes to the ND.

the flight was on LNAV and VNAV and FL380.

the 777 shows the TRUE and GRID heading.

but at the waypoints N82W020 N85W060 N84W090 around 10 miles before we passing

the points the 777 lost the correct heading and fly 2,5 miles left then right of

the route. then the plane courve back to the flightpath.

My Question: what i doing wrong with this great plane on my polar flight??

sorry for my bad english!

greetings Kalle near EDDW

Per FCOM do not change to TRUE if using LNAV for roll control. Leave it in MAG and it will do just fine.

When entering the Polar region, automatic switching to true North will happen at various latitudes, and it will be announciated by a flashing white box around the word TRU on your ND.

When you exit the Polar region, you'll notice a green box around the word MAG, again on ND.

Look carefully for alternates in that area, there's nothing much around )

FCOM has more detail but from FCTM pg 4.17: "The primary roll mode for polar operations should be LNAV, which may be used with the heading reference switch in the NORM position. HDG SEL/HOLD and TRK SEL/HOLD are functional but require the manual selection of TRUE heading reference." As I said, use LNAV and don't select TRUE heading/track unless you want to deviate from course.

Hi all,

thanks for the answers, now i know the roules.

 

greetings Kalle near EDDW