How is the 60% rule applied?
There are two valid methods to apply the 60% landing distance rule:
Method 1: Factor the Runway Length
If LDA = 5,000 ft
→ 5,000 × 0.60 = 3,000 ft
→ Your AFM landing distance must be ≤ 3,000 ft
Method 2: Factor the AFM Landing Distance
If AFM landing distance = 2,250 ft
→ 2,250 ÷ 0.60 = 3,750 ft
→ 2,250 × 1.67 = 3,757.5 ft
→ Both are < 5,000 ft LDA → Safe to land
Important: Do not compare factored landing distances to factored runway lengths. That would apply the safety margin twice, which is overly conservative.
Method 1: Factor the Runway Length
- Multiply the Landing Distance Available (LDA) by 0.60.
- Choose a landing weight that results in an unfactored landing distance (from the AFM) that is less than or equal to this value.
If LDA = 5,000 ft
→ 5,000 × 0.60 = 3,000 ft
→ Your AFM landing distance must be ≤ 3,000 ft
Method 2: Factor the AFM Landing Distance
- Take the unfactored landing distance from the AFM and divide it by 0.60, or multiply by 1.67
- Compare this result to the LDA
If AFM landing distance = 2,250 ft
→ 2,250 ÷ 0.60 = 3,750 ft
→ 2,250 × 1.67 = 3,757.5 ft
→ Both are < 5,000 ft LDA → Safe to land
Important: Do not compare factored landing distances to factored runway lengths. That would apply the safety margin twice, which is overly conservative.