Air traffic controllers in towers primarily use ______ to track and control aircraft. A: VORTAC B: NDB C: Sight D: VOR

A VORTAC is a facility consisting of two components, VOR/DME and TACAN. VOR signals can be used by ______ receivers and TACAN for ______ aircraft. A: civilian, civilian B: military, military C: civilian, military D: military, civilian