The runway may be extended by an area called the stopway. The stopway is an area beyond the runway, which should have the following characteristics. It must be : 

. At least as wide as the runway, and centered upon the extended centerline of the runway. 

. Able to support the airplane during an abortive takeoff, without causing structural damage to the airplane. 

. Designated by the airport authorities for use in decelerating the airplane during an abortive takeoff. 

“JAR-OPS 1.480 (a)(1) Accelerate-Stop Distance Available (ASDA): The length of the takeoff run available plus the length of the stopway, if such stopway is declared available by the appropriate Authority and is capable of bearing the mass of the aeroplane under the prevailing operating conditions.” 

“JAR-OPS 1.490 (b)(1) The accelerate-stop distance must not exceed the accelerate-stop distance available.” 

ASD ≤ ASDA 

3.2.4. Loss of Runway Length due to Alignment 

Airplanes typically enter the takeoff runway from an intersecting taxiway. The airplane must be turned so that it is pointed down the runway in the direction for takeoff. FAA regulations do not explicitly require airplane operators to take into account the runway distance used to align the airplane on the runway for takeoff. On the contrary, JAA regulations require such a distance to be considered: 

“JAR-OPS 1.490 (c)(6) […] an operator must take account of the loss, if any, of runway length due to alignment of the aeroplane prior to takeoff.” 

Lineup corrections should be made when computing takeoff performance, anytime runway access does not permit positioning the airplane at the threshold. 

The takeoff distance / takeoff run (TOD / TOR) adjustment is made, based on the initial distance from the beginning of the runway to the main gear, since the screen height is measured from the main gear, as indicated by distance "A" in Figure C12. The accelerate-stop distance (ASD) adjustment is based on the initial distance from the beginning of the runway to the nose gear, as indicated by distance "B" in Figure C12. 

Runways with displaced takeoff thresholds, or ample turning aprons, should not need further adjustment. Accountability is usually required for a 90° taxiway entry to the runway and a 180° turnaround on the runway. The following tables (C2 and C3) contain the minimum lineup distance adjustments for both the accelerate-go (TOD/TOR) and accelerate-stop (ASD) cases that result from a 90° turn onto the runway and a 180° turn maneuver on the runway. For further details, refer to the Airbus Performance Program Manual (PPM). 

3.2.4.1. 90 Degree Runway Entry 

Table C2: 90° Lineup Distances 

3.2.4.2. 180 Degree Turnaround 

180 Degree Turnaround 

Required Minimum Nominal Line up Aircraft Model Minimum Line up Distance on a 60 m Runway Distance correction * 

runway width ** TODA (m) 

width 

Table C3: 180° Lineup Distances 

* Lineup distance required to turn 180 degrees at maximum effective steering angle and end aligned with the centerline of the pavement. The indicated minimum runway width is required (Figure C14, left hand side). 

** Lineup distance required to turn 180 degrees and realign the airplane on the runway centerline on a 60 m wide runway (Figure C14, right hand side). 

3.2.5. Influence of V1 on the Runway-Limited Takeoff Weight 

Considering the runway requirements (TOR≤TORA, TOD≤TODA, and ASD≤ASDA), a Maximum Takeoff Weight (MTOW) can be obtained for each runway limitation. As an example, when for a given takeoff weight the TOD is equal to the TODA, this takeoff weight is maximum regarding the Takeoff Distance limitation. 

As previously seen, for a given takeoff weight, any increase of V1 leads to shortening the TODN-1 and TORN-1, and increasing the ASD, but has no influence on TODN and TORN. 

Therefore, for a given runway (i.e. given TORA, TODA and ASDA), any increase in V1 leads to an increase in the MTOWTOD(N-1) and MTOWTOR(N-1), and to a reduction in MTOWASD, but has no influence on MTOWTOD(N) and MTOWTOR(N). 

The following graph (Figure C15) provides the runway-limited accelerate-go/stop takeoff weights as a function of V1. This graph clearly shows that a maximum takeoff weight is achieved in a particular range of V1. 

4. CLIMB AND OBSTACLE LIMITATIONS 

4.1. Takeoff Flight Path 

4.1.1. Definitions 

“JAR/FAR 25.111