The world's largest aircraft took off over the Mojave Desert in California on Saturday, the first flight for the carbon-composite plane built by Stratolaunch Systems Corp, started by late Microsoft co-founder Paul Allen, as the company enters the lucrative private space market.
Mr Thomas said there were "a few little things that were off-nominal but really for a first flight it was spot on".
Importantly, Saturday's flight was just a test - no rockets were launched from the giant plane as it soared at 17,000 feet.
"We finally did it", said Stratolaunch Systems CEO Jean Floyd at a news conference from the hangar at Mojave Air & Space Port.
The massive, twin-fuselage Stratolaunch jet created to air-launch rockets into orbit lifted off from Mojave Air and Space Port early Saturday.
The aircraft is created to release rockets attached to the center of its enormous wing, which stretches 385 feet (117 meters) from tip to tip - a longer wingspan than any other aircraft.
The advantages of such air-launch systems include being able to use airports and avoid the limitations of fixed launch sites which can be affected by weather, air traffic and ship traffic on ocean ranges.
Stratolaunch recently dropped plans to develop its own line of rockets and will focus on launching Northrop Grumman's Pegasus XL.
The aircraft taking off from Mojave, California. Its twin fuselages - sort of the airplane equivalent of a catamaran - are 238 feet (72.5 meters) long. Surviving in an aviation museum, it has an approximately 320-foot wingspan but is just under 219 feet long.
Though Stratolaunch is the largest plane by wingspan, another craft, the helium-filled Airlander 10, takes the title of the longest aircraft now flying with a length of 302 feet (92 m). The plane has two fuselages each with its own cockpit-though only one is needed to fly-6 Pratt & Whitney engines, usually found on Boeing 747s, and 28 wheels for its landing gear.