Decision Altitude (DA):

As per the definition of Decision Altitude (DA), a missed approach must be initiated immediately upon reaching the DA if the required visual reference is not established.

Key points:

1. No Straight and Level Flight:
   • At DA, there should be no continuation of flight at a level altitude waiting for visual cues. The DA already accounts for the potential “dip down” during the missed approach maneuver.
2. Vertical Guidance:
   • Since DA is associated with precision approaches, vertical guidance is available (e.g., from ILS or LPV approaches), ensuring the aircraft remains on a controlled descent path until the missed approach is executed.
3. Immediate Missed Approach:
   • If visual references are not available upon reaching DA, an immediate missed approach is required to ensure safety and compliance with procedure.

The design of DA ensures that all necessary margins for terrain clearance and aircraft performance are accounted for, emphasizing the importance of decisive action at this critical point.