The ability to fly without apparent means of propulsion or lift.
No observable wings, tail, or engines which could account for propulsion through the air.
The ability for a craft to reach a high rate of speed in a short amount of time
A craft’s Ability to reach speeds of 3,700 miles per hour (5x the Speed of Sound). Without emitting a “sonic boom.”
A craft’s ability to conceal itself from any kind of radar. Or become difficult to observe due to some kind of cloaking.
A craft’s ability to move seamlessly between space, air and water.