Boeing 747-123, N905NA, 20 September 1974 Published on February 17, 2013 in 18 February 1977Full resolution (3000 × 2323) ← Previous Next → Boeing 747-123, N905NA, during wake vortex studies, 20 September 1974. The other aircraft are a Cessna T-37 and a Lear Jet. (NASA)