An approach slope is the path that an airplane follows on its final approach to land on a runway. It takes its name from the fact that this path is ideally a gentle downward slope. A commonly used approach slope is 3° from the horizontal. However, certain airports have steeper approach paths based on topography, buildings, or other considerations. E.g., London City Airport has a 5.5° approach, and only aircraft that can maintain such an approach are permitted to use the airport.[4]
The term glide slope is often applied to mean approach slope although to be correct glide slope applies to the vertical guidance element of the Instrument Landing System.[2]