After years of successful trans-Atlantic flights, the age of supersonic jet travel came to an end in October 2003, when British Airways permanently grounded the Concorde. Driven in part by the enthusiasm and excitement over faster, autonomous travel, these supersonic jets are being tested once again. Japan Airlines has invested $10 million in Boom Technology to develop supersonic jets, which will travel at 2.2 times the speed of sound—about twice as fast as a traditional aircraft. (Japanese Airlines has already pre-ordered 20.) All Nippon Airways is also researching supersonic flight. Aerion, Lockheed Martin and GE Aviation are developing a supersonic business jet that could carry 12 passengers. The new supersonic airplanes will allow flights to take off over land, which because of the sonic boom, had limited the success of the original Concorde. Fuel efficiency and safety concerns, however, could slow getting to market in the short term.