In 1977, US carrier Eastern Air Lines leased four A300s as an in-service trial. Frank Borman, ex-astronaut and the then CEO of the airline, was impressed that the A300 consumed 30% less fuel, even less than expected, than his fleet of L-1011s. Borman proceeded to order 23 A300s, becoming the first U.S. customer for the type. This order is often cited as the point at which Airbus came to be seen as a serious competitor to the large American aircraft-manufacturers Boeing and McDonnell Douglas. Aviation author John Bowen alleged that various concessions, such as loan guarantees from European governments and compensation payments, were a factor in the decision as well. The Eastern Air Lines breakthrough was shortly followed by an order from Pan Am. From then on, the A300 family sold well, eventually reaching a total of 561 delivered aircraft.