The Lockheed L-188 Electra is an American turboprop airliner built by Lockheed. First flown in 1957, it was the first large turboprop airliner built in the United States. Initial sales were good, but after two fatal crashes that led to expensive modifications to fix a design defect, no more were ordered. With its unique high power-to-weight ratio, huge propellers and very short wings, large Fowler flaps which significantly increased effective wing area when extended, and four-engined design, the airplane had airfield performance capabilities unmatched by many jet transport aircraft even today—particularly on short runways and high field elevations. Jet airliners soon supplanted turboprops for many purposes, and many Electras were modified as freighters. Some Electras are still being used in various roles into the 21st century. The airframe was also used as the basis for the much more successful Lockheed P-3 Orion maritime patrol aircraft.