Aviation is viewed as a growth industry with technological advances continuing well into the 21st Century. While growth constraints to air transportation such as economics, energy, and congestion are very real, technical improvements in dependability, efficiency, and speed will tend to counteract them. Certain NASA activities which impact long-haul (greater than 500 miles) and far-term air transports (1990's and beyond) are discussed. The keys to improved dependability are congestion relief and all-weather operations. Progress in all-weather 4-D navigation and wake vortex attenuation research is discussed and the concept of time-based metering of aircraft is recommended for increased emphasis. The far-term advances in aircraft efficiency are shown to be skin-friction reduction and advanced configuration types. The promise of very large aircraft - possibly all-wing aircraft - is discussed, as is an advanced concept for an aerial relay transportation system. Very significant technological developments are identified that can improve supersonic transport performance and reduce noise. The hypersonic transport is proposed as the ultimate step in air transportation in the atmosphere. Progress in the key technology areas of propulsion and structures is reviewed. Finally, the impact of alternate fuels on future air transports is considered and shown not to be a growth constraint.