Definition
A ground-based radio transmitter, part of an Instrument Landing System (ILS), that radiates a directional signal in the ultra-high frequency band (329.15--335.0 MHz) to define the correct vertical descent path to a runway. The aircraft's glideslope receiver interprets this signal and displays whether the aircraft is on, above, or below the prescribed descent angle, typically about 3 degrees.
Plain English
A radio transmitter beside the runway that sends out a beam telling the aircraft whether it is descending at the right angle to land. The cockpit instrument shows the pilot if they are too high, too low, or right on the slope.
Context Anchor
Seen in instrument landing system diagrams, approach discussions, and equipment status notices for ILS approaches.
Derivation
UHF stands for Ultra High Frequency, the radio band the transmitter uses (300 MHz to 3 GHz). 'Glideslope' combines 'glide' (a controlled descent) with 'slope' (an inclined path), describing the angled descent line the signal defines.
Why Pilots Care
It supplies the vertical guidance signal required for safe precision approaches in low visibility.
Intuition Check
Do not think of the UHF Glideslope Transmitter as giving all ILS guidance by itself. It gives the vertical path; left-right runway alignment comes from the localizer signal.
Example Sentence 1
As the aircraft intercepted the final approach course, the glideslope needle came alive, indicating the UHF glideslope transmitter signal had been acquired.
Example Sentence 2
Maintenance confirmed the UHF glideslope transmitter signal was within tolerance for Category I minima.