The Mysterious Airman (1928)

An inventor adds new innovations to Baker Airplane Company's planes, inventions coveted by the owners of a rival company. The masked and mysterious airman, known only as Pilot X, makes plans to steal the inventions for his own purposes. The perils are fast and furious as the owner of the airplane company, aided by his aviatrix fiancee, find themselves in constant danger, both on land and in the air.