flexible control cable (aircraft control system component). A steel cable used to connect the cockpit
controls to the control surfaces. Flexible cable is made up of seven strands of wire, with each stand being made up of seven individual wires. This is called 7 x 7 cable.
Extra-flexible cable has seven strands, with each strand made of 19 wires, and nonflexible cable is made of either seven or 19 solid wires wound into a cable.

“Flight check” (air traffic control). A call-sign prefix used by FAA aircraft engaged in flight inspection/certification of navigational aids and flight procedures.
flight controller (automatic pilot component). The command unit of an automatic pilot. The human pilot is able to control the flight of the aircraft when the automatic pilot is engaged by using the controls on the flight controller.
flightcrew member. 14 CFR Part 1: “A pilot, flight engineer, or flight navigator assigned to duty in an aircraft during flight time.”
flight deck (aircraft compartment). The compartment in a large aircraft in which all the flight, engine, communications, and navigation controls are located.