Definition
A digital radio transmission, in the 108.025–117.950 MHz VHF band, used by a Ground-Based Augmentation System (GBAS) ground station to send GPS correction data, integrity information, and approach path definitions to aircraft. The broadcast allows a properly equipped aircraft to compute precision approach guidance to a GBAS-served runway.
Plain English
It's the radio signal a ground station uses to send GPS correction data and approach path information up to the aircraft, so the aircraft can fly a precise GPS-based approach to the runway.
Context Anchor
Seen in GBAS approach discussions, where the aircraft must receive the airport’s GBAS broadcast before it can use GBAS guidance.
Derivation
VHF stands for Very High Frequency, the radio band (30–300 MHz) already used for voice communications and VOR navigation. 'Data broadcast' simply means the signal carries digital data rather than voice. So VDB is a digital data signal sent on the same general band of radio used for everyday cockpit communications.
Why Pilots Care
Enables GBAS approaches that provide precision guidance similar to ILS but with greater flexibility in runway ends served.
Intuition Check
Do not think of VDB as a two-way radio conversation. In this context, the GBAS station broadcasts information out, and the aircraft receives it.
Example Sentence 1
The GBAS ground station transmits correction data to arriving aircraft over the VHF data broadcast.
Example Sentence 2
VDB broadcasts from the ground station ensure the integrity of the satellite data used for the final approach segment.