Which NAVAID generates directional information and transmits it to the aircraft?

The correct answer is TACAN. TACAN, or Tactical Air Navigation, is a navigational aid that provides both distance information and directional information to aircraft. It operates on UHF frequencies and gives pilots precise bearing information, which is essential for navigation and approach procedures. The system transmits a signal from the ground station that allows an aircraft's onboard equipment to calculate the aircraft's position relative to the TACAN station, offering a combination of range and bearing data.

While other options like VOR and NDB also provide directional information, they operate using different principles and frequencies. VOR (VHF Omnidirectional Range) provides azimuth information using VHF signals but does not include distance measurement. NDB (Non-Directional Beacon) transmits signals in all directions but lacks the ability to provide precise directional fixing that TACAN offers, as it requires the use of the aircraft's ADF (Automatic Direction Finder) system. DME (Distance Measuring Equipment), on the other hand, only provides distance information and does not give directional data.

Thus, TACAN stands out as the comprehensive NAVAID that uniquely delivers both distance and directional information to aircraft, making it a critical tool in their navigation arsenal.