The TODA is the distance declared available for satisfying takeoff distance requirements for airplanes where the certification and operating rules and available performance data allow for the considera-tion of a clearway in takeoff performance computa-tions.
NOTE.
The length of any available clearway will be included in the TODA published in the A/FD’s entry for that runway end.
 c) Accelerate.Stop Distance Available (ASDA) – The runway plus stopway length declared available and suitable for the acceleration and deceleration of an airplane aborting a takeoff.
The ASDA may be longer than the physical length of the runway when a stopway has been designated available by the airport operator, or it may be shorter than the physical length of the runway if necessary to use a portion of the runway to satisfy runway design standards; for example, where the airport operator uses a portion of the runway to achieve the runway safety area requirement. ASDA is the distance used to satisfy the airplane accelerate.stop distance performance requirements where the certification and operating rules require accelerate.stop distance computations.
NOTE.
The length of any available stopway will be included in the ASDA published in the A/FD’s entry for that runway end.
 d) Landing Distance Available (LDA) . The runway length declared available and suitable for a landing airplane.
The LDA may be less than the physical length of the runway or the length of the runway remaining beyond a displaced threshold if necessary to satisfy runway design standards;for example, where the airport operator uses a portion of the runway to achieve the runway safety area requirement.
Although some runway elements (such as stopway length and clearway length) may be available information, pilots must use the declared distances determined by the airport operator and not attempt to independently calculate declared distances by adding those elements to the reported physical length of the runway.
8.5.2.2 The airplane operating rules and/or the airplane operating limitations establish minimum distance requirements for takeoff and landing and are based on performance data supplied in the Airplane Flight Manual or Pilot’s Operating Handbook. The minimum distances required for takeoff and landing obtained either in planning prior to takeoff or in performance assessments conducted at the time of landing must fall within the applicable declared distances before the pilot can accept that runway for takeoff or landing.
8.5.2.3 Runway design standards may impose restrictions on the amount of runway available for use in takeoff and landing that are not apparent from the reported physical length of the runway or from runway markings and lighting. The runway elements of Runway Safety Area (RSA), Runway Object Free Area (ROFA), and Runway Protection Zone (RPZ) may reduce a runway’s declared distances to less than the physical length of the runway at geographically constrained airports (See FIG ENR 1.1.5). When considering the amount of runway available for use in takeoff or landing performance calculations, the declared distances published for a runway must always be used in lieu of the runway’s physical length.
REFERENCE.
AC 150/5300.13, Airport Design.
8.5.2.4 While some runway elements associated with declared distances may be identifiable through runway markings or lighting (for example, a displaced threshold or a stopway), the individual declared distance limits are not marked or otherwise identified on the runway. An aircraft is not prohibited from operating beyond a declared distance limit during the takeoff, landing, or taxi operation provided the  runway surface is appropri-ately marked as usable runway (See FIG ENR 1.1.5). The following examples clarify the intent of this paragraph.
REFERENCE.
AIM, Runway Markings, Paragraph 2.3.3..
AC 150/5340.1, Standards for Airport Markings.

EXAMPLE.
1. The declared LDA for runway 9 must be used when showing compliance with the landing distance require-ments of the applicable airplane operating rules and/or airplane operating limitations or when making a before landing performance assessment. The LDA is less than the physical runway length, not only because of the displaced threshold, but also because of the subtractions necessary to meet the RSA beyond the far end of the runway. However, during the actual landing operation, it is permissible for the airplane to roll beyond the unmarked end of the LDA.

Federal Aviation Administration Twentieth Edition
2. The declared ASDA for runway 9 must be used when necessary to achieve the full RSA requirement. However, in showing compliance with the accelerate.stop distance the event of an aborted takeoff, it is permissible for the requirements of the applicable airplane operating rules airplane to roll beyond the unmarked end of the ASDA as and/or airplane operating limitations. The ASDA is less it is brought to a full.stop on the remaining usable runway. than the physical length of the runway due to subtractions
　
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