# What are Runway Declared Distances?

Perusing through the A/FD in the United States I see that some runways have declared distances while others do not.

What is the meaning of:

1. TODA
2. TORA
3. ASDA
4. LDA

From the AIM, 4-3-6 (c)(2):

All 14 CFR Part 139 airports report declared distances for each runway. Other airports may also report declared distances for a runway if necessary to meet runway design standards or to indicate the presence of a clearway or stopway. Where reported, declared distances for each runway end are published in the Airport/Facility Directory (A/FD). For runways without published declared distances, the declared distances may be assumed to be equal to the physical length of the runway unless there is a displaced landing threshold, in which case the Landing Distance Available (LDA) is shortened by the amount of the threshold displacement.

Now for definitions. These terms are defined by the FAA/ICAO in the PCG.

TODA - Takeoff Distance Available. The takeoff run available plus the length of any remaining runway or clearway beyond the far end of the takeoff run available.

TORA - Takeoff run available. The runway length declared available and suitable for the ground run of an airplane taking off.

ASDA - Accelerate-Stop Distance Available. The runway plus stopway length declared available and suitable for the acceleration and deceleration of an airplane aborting a takeoff.

LDA - Landing Distance Available. The runway length declared available and suitable for a landing airplane.

(also Declared Distances from wikipedia)

then for those specified limits of the clearway, in 14 CFR Part 1 we find