1956 KANO, NIGERIA. When taking off from Kano, the B.O.A.C. aircraft, en route from Kano, Nigeria to Tripoli, Libya and then London hit a tree, crashed, caught fire and exploded. Of the 38 passengers and seven crew members, 19 were saved. A small part of the mail was recovered and a cachet applied. This air letter from Enugu to London has a superb example of the three line violet cachet.