When should landing distance be considered in relation to the use of LDG flaps?

Considering landing distance in relation to the use of LDG flaps is important as it directly affects the aircraft's performance during approach and landing. When the landing distance is close to 80% of the actual field length, it indicates that the aircraft is operating within a critical performance margin. At this point, using landing flaps becomes advantageous because they enhance the aircraft's lift and control characteristics during approach, allowing for a more stable and slower descent.

Using LDG flaps helps in achieving a steeper approach angle while maintaining a manageable landing speed, which can be crucial when the remaining landing distance is limited. If the landing distance approaches or exceeds 80% of the actual runway length, pilots must carefully manage the landing configuration to ensure a safe touchdown and rollout, thereby enhancing safety and operational efficiency.

In contrast, the other choices providing thresholds that are too high or too low do not align with the critical performance considerations when near the limits of safe landing distance.