When can you descend below a descent restrictive altitude on an ILS?

Descending below a descent restrictive altitude on an Instrument Landing System (ILS) approach is permitted once visual reference is established. This is a key principle in instrument flying, as the pilot must have visual contact with the runway environment to ensure a safe landing. When a pilot transitions from flying solely on instruments to using visual references, it legitimizes further descent, aligning with the fundamental safety protocols that govern aviation operations.

The concept of visual reference is essential since it indicates that the pilot can confirm their positional awareness relative to the runway or landing environment. This is typically accomplished through visual cues such as the runway lights, the runway itself, or other landmarks.

In practice, even if a pilot is approximately on the final approach course, they still need to verify their visual contact before continuing below the restrictive altitude. Other aspects, such as passing the outer marker or following ATC instructions, may provide context to the approach but do not directly permit descent beyond the restrictions without visual confirmation. The primary focus remains on ensuring safety through visual confirmation before proceeding with the landing.