15.3 Grid Navigation
In the event of any major failure of the FMS the crew could use the last airplane position to plot a track to the desired destination, measure the track and distance and navigate by Mental DR till suitable Navigation Aids are available. At any point on track the true heading/track could be measured while aligning the protractor along the meridian at the place. The True heading/track would change by an amount equal to the meridian convergence at any other place. The crew could also use the formula to calculate the true track/heading at any point .
GRID TRACK= TRUE TRACK + LONG WEST
-LONG EAST

Since the ND displays GRID headings beyond 70° N latitude these could be used to maintain single heading to the destination.
Issue I 28.08.2007 Rev.0

POLAR OPERATIONS MANUAL 極地運行手冊

 CONTENTS PAGE 0-1
CONTENTS

 Contents  0-1 to 0-2 
Revision  0-3 
List of Controlled Copy Holders  0-4 
References  0-5 
Policy/Purpose/Approval  0-6 
1. Polar, Russia & Far East  1-1 
2. Preflight Planning  2-1 
3. Non Polar Dispatch  3-1 to 3-2 
4. Outside Air Temperature (Oat), Fuel Temperature, Fuel Freeze Values  4-1 
5. Flight Deck Preparation  5-1 
6. Polar Exposure Suits  6-1 to 6-2 
7. Enroute Communications  7-1 to 7-4 
8. Company Communications  8-1 to 8-2 
9. Route Specifics  9-1 to 9-5 
10. Irregular Operations  10-1 to 10-2 
11. Russian Procedures  11-1 to 11-8 
12. Polar Alternate/Diversion Airports  12-1 to 12-5 
13. Inflight Radiation Exposure  13-1 to 13-2 
14. Training Requirements  14-1 
15. Grid Navigation and Plotting  15-1 
16. Minimum Equipment List  16-1