1. Maintain VMC!
2. Choose somewhere visually significant from which to divert.
3. Fly to this ‘divert point’.
4. The back of the checklist (ours are laminated and have a blank back with a 50 mile half-mill scale on one edge!), a chinagraph and the CAA half-mill chart are the only planning tools needed:
5. Use the edge of the checklist as a ruler between divert point and diversion and draw the track line on the chart. Then lookout.
6. Measure the length of the line, write it on the checklist – then lookout again
7. Make sure the divert point is still in sight!
8. Find a suitable VOR rose on the chart, use the checklist edge as a parallel rule and draw a line through the VOR rose parallel to the diversion track. Then lookout.
9. Read off the track angle – which, of course, is conveniently in degrees magnetic – write it on the checklist. Lookout again.
10. The 2 most important values, track and distance, are now known. Apply MDR to track (the pre-calculated max drift value is on the chart, of course!) and estimate the heading.
11. Note the head or tailwind component and work out groundspeed to the nearest ¼ mile per minute. Then use it as a fraction (e.g. 5/4 miles per min rather than 75 knots) – the error over the short distance involved is unlikely to be significant.
12. The hardest sum next! Time = Distance / Speed! Either mentally or on the back of the checklist. Write it down, then lookout.
13. Pre-HAAT check, overfly the divert point, post-HAAT check.
14. Fly heading and time diligently. Lookout and look down for visually significant points to confirm track maintenance.
15. At this point, I would certainly allow a student, who had demonstrated the ability to cope using 1-14 above, to use radio navigation or GPS to confirm his/her work.