Final answer:
The glide slope is the part of the Instrument Landing System that transmits a beam at an angle to provide vertical guidance for aircraft during approach.
Step-by-step explanation:
The part of the Instrument Landing System (ILS) that transmits a beam to the plane at right angles to the localizer beam and at the ideal approach-path angle is known as the glide slope. The glide slope provides vertical guidance to aircraft by transmitting a beam upwards from the runway at a consistent angle, typically between 2.5 to 3 degrees. Along with the localizer, which provides horizontal guidance, the glide slope ensures that the aircraft is on the correct approach path to the runway for a safe landing.