The Grob 109 or Vigilant as we know it, differs from other air Cadet Gliders in that it has an engine and propeller, so it can launch itself.

The Vigilant can taxi, take off and climb under its own power to a height selected by the instructor. It can be flown as a glider by allowing the engine to idle or, for some advanced exercises with the engine off all together. It can soar in thermals given reasonable thermic conditions. The engine is not powerful enough for rapid climbing, taking some 5 minutes or so to reach 2,000 feet. However the ground handling time is reduced and manpower requirements are less than the Viking.

The Vigilant is used for GIC, GS and AGT training and, unlike the Viking where you may experience a number 5-7 minute flights in order to achieve training objectives, Vigilant sorties typically last for about 45 minutes.

The Vigilant T MK 1 is a self launching motor glider designed and built in Germany but modified to incorporate RAF requirements.