One important safety measure used during research flights is the chase aircraft. The chase pilot follows the research aircraft as it makes the research flights, watching for any problems such as fuel leaks, fire, or the landing gear not being fully retracted or extended. During the early flights of the X-1, a P-80 was used as the chase airplane.

The higher speeds of the X-1A and -B, the D-558-2s, and the X-2 required the faster F-86 to be used as chase aircraft. By the time of the X-15, both Air Force and NASA F-104s were serving as chase airplanes. By the early 1980s, NASA's remaining F-104s had been in service for 20 years or more. Parts were becoming hard to find, and the aircraft were more expensive to operate. A replacement was needed. This arrived in the form of the Navy F/A-18, of which NASA acquired many pre-production and early models.

A major technical advance of the two-seat F-18 chase plane was the ability to transmit live television images to ground controllers. Before this, a chase pilot could only offer radio descriptions. With the live television, the controlers have more information, and there is no delay for processing. Also, a photographer or videographer can sit in the back seat and provide further documentation of the research aircraft in flight.