Hello, this air mail cover was issued in 1981 to commemorate the 50th Anniversary of Francis Chichester’s solo flight across the Tasman. This was the first east west flight across the Tasman.

Some more about his flight that may interest you. Finding that he was unable to carry enough fuel to cross the Tasman Sea  directly, Chichester had his Gipsy Moth fitted with floats borrowed from the New Zealand Permanent Air Force,  and went on to make the first solo flight across the Tasman Sea from East to West (New Zealand to Australia). He was the first aviator to land an aircraft at Norfolk Island and Lowe Howe Island.  Again, the trip was delayed: after his aircraft was severely damaged at Lord Howe, he had to rebuild it himself with the help of islanders.

Though the concept of “off-course navigation” (steering to one side so you know which way the error is) is probably as old as navigation, Chichester was the first to use it in a methodical manner in an aircraft. His only method of fixing his position was to take sun sights with a sextant.  As a solo pilot, this was a difficult thing to do in a moving aircraft, as the pilot also needed to fly the aircraft at the same time. After the sun sight was taken, he then had to make calculations by long-hand. As all this could be unreliable, Chichester needed an alternative. When he reached a point at which the sun was at a pre-calculated altitude above the horizon, the pilot then made a 90-degree turn to the left (or right as pre-calculated) and then flew along this line until the destination was reached. Since he did not know in advance when he would arrive at a line of position passing through his destination, he pre-calculated a table or graph of the Sun’s altitude and azimuth at his destination for a range of times bracketing his ETA. The advantage of this method was that the effects of drift were reduced to errors in distance travelled, usually much smaller. Since Chichester arrived at Lord Howe Island in the afternoon, the Sun was to his northwest when he made his turn. Some hours before making his turn, close to local noon when the Sun was to his north, Chichester made two observations with his sextant to check his dead-reckoning course.

The general principle was, when the Sun is to the right or left of one’s course one can check one’s course but not one’s distance to the destination. When the Sun is ahead or behind one’s course one can check the distance to one’s destination but not one’s course. So he planned his final approach to follow a line of position directly to his destination. This technique allowed him to find tiny islands in the Pacific. He was awarded the inaugural Guild of Air Pilots & Air Navigators Johnston Memorial Trophy for this trip

see how interesting collecting stamps can be 🙂

best wishes .. Michael