High speed VSTOL aircraft that can cruise between 300 and 400 knots are becoming technically and economically feasible. As civil transports, they could help relieve congestion at major airports around the world.Demonstrator vehicles have proven that tilt wing and tilt rotor aircraft can meet performance expectations. Advances in propulsion, materials, flight controls and avionics places aviation on the threshold of truly practical and cost effective high speed VSTOL aircraft.The Bell XV-15 tilt rotor and the Canadair CL-84 tilt wing aircraft were successful demonstrators. They are nearly identical in size, weight and available power; thus, there is a good opportunity to make realistic capability comparisons.Future markets for tilt wing and tilt rotor aircraft range from small unmanned aerial vehicles (UAV'S) to large 40-passenger transports. Above this size it becomes more practical to use a tilt wing STOL design.A nine-passenger (11 seats) tilt wing vehicle about the size of the XV-15 and CL-84 1s considered the most logical first generation high speed VSTOL aircraft for civil roles and search and rescue (SAR) missions.Design issues and factors relating to the tilt wing and tilt rotor are reviewed. There are many differences, but perhaps most visible are the small diameter propellers on tilt wing aircraft and large diameter rotors on tilt rotor aircraft.There is a real need to do something in a hurry to relieve the congestion existing at major airports. Certain key assumptions are made and the challenge is to put these assumptions in place.