Sir - During a recent overnight transatlantic flight, it was interesting to see a wonderful display of the Aurora Borealis northern lights.
It is perhaps not surprising that HF radio transmissions were considerably disturbed (with quite a network of relay calls between aircraft) and Shanwick and Gander each doing a grand job to pass through position reports.
Although I know little about geophysics, I believe that the period of maximum and minimum intensity of the aurora follows almost exactly that of the 11-year Sun-spot cycle.
Perhaps lucky night aviators have something to which they can look forward to for a while.
TOM COLDICOTT
Tunbridge Wells, Kent, UK
Source: Flight International
