a device that requires skill for proper use

a navigational instrument based on a gyroscope; it artificially provides a simulated horizon for the pilot

navigational instrument for finding directions

navigational instrument used to measure the depth of a body of water (as by ultrasound or radar)

an instrument showing the angle that an aircraft makes with the horizon

a measuring instrument that sends out an acoustic pulse in water and measures distances in terms of the time for the echo of the pulse to return