How does ASDA being shorter than TORA affect takeoff performance?

It depends on whether the aircraft uses balanced or unbalanced takeoff data:

Balanced Field Length:

• Accelerate-go and accelerate-stop distances are equal.
• The shorter ASDA becomes the limiting factor.
• You must ensure your required field length is less than or equal to ASDA.

Unbalanced Takeoff:

• Accelerate-stop must be ≤ ASDA.
• Accelerate-go may exceed ASDA, up to TORA + clearway (if applicable).
• Allows for more flexibility, but still requires careful analysis.

Many charts and FMS databases only show TORA, not ASDA. This can give the false impression that the full runway is available for both accelerate-go and accelerate-stop operations.

For example, at Teterboro (KTEB):

• Runway 01 has a TORA of 7,000 ft.
• But the ASDA is only 6,090 ft.

If using balanced data, your takeoff performance must be based on 6,090 ft, not 7,000 ft.

How common is this?

Over 250 U.S. airports have ASDA values shorter than TORA. Some notable examples include:

• KATL (Atlanta)
• KORD (Chicago O’Hare)
• KLAS (Las Vegas)
• KSFO (San Francisco)
• KTEB (Teterboro)