For the U.S. commercial aviation industry last week, the ceiling looked unlimited. Pan American World Airways announced a $110 million order with Douglas Aircraft for 40 of its speedy (365 m.p.h.) piston-engined DC-7s, the biggest order ever placed by an airline with a single manufacturer. Two days later, Northwest Airlines ordered another 14 Douglas planes costing $28 million. Together, the two boosted Douglas' backlog to 156 planes, worth more than $500 million, the highest figure in its history. At rival Lockheed, orders were on hand for $225 million worth of Constellations.
The big Douglas and Lockheed orders meant that U.S. airlines...