vertical сontrol operator

vertical control operator

vortex сontrol

visual сontrol signal

amphibious сontrol vessel

security сontrol officer

close-сontrol bombing

damage-сontrol bill

damage-сontrol officer

instantaneous vertical speed indicator / instantaneous vertical-speed indicator (IVSI)

air traffic control operator

control tower operator

early warning system (EWS) operator

identification operator

operator control unit (OCU)

operator maintenance

operator’s pack

operator's permit

ship operator

telephone operator

radio telephone operator (RTO)

aiming rule operator

azimuth (deflection) display board operator

control post operator

fire-control operator

navigator-radio operator

air operator certificate

aircraft operator

airport operator

flight operator

flight radio operator

flight systems operator

operator  D / Dt