CAT.POL.A.205 Take-off

LOSS OF RUNWAY LENGTH DUE TO ALIGNMENT

(a)The length of the runway that is declared for the calculation of take-off distance available (TODA), accelerate-stop distance available (ASDA) and take-off run available (TORA) does not account for line-up of the aeroplane in the direction of take-off on the runway in use. This alignment distance depends on the aeroplane geometry and access possibility to the runway in use. Accountability is usually required for a 90°-taxiway entry to the runway and 180°-turnaround on the runway. There are two distances to be considered:

(1)the minimum distance of the main wheels from the start of the runway for determining TODA and TORA,’L’; and

(2)the minimum distance of the most forward wheel(s) from the start of the runway for determining ASDA,’N’.

Figure 1 Line-up of the aeroplane in the direction of take-off — L and N [Figure or form omitted from this preview — available in the Avioverse workspace library.] Where the aeroplane manufacturer does not provide the appropriate data, the calculation method given in (b) should be used to determine the alignment distance.

(b)Alignment distance calculation [Figure or form omitted from this preview — available in the Avioverse workspace library.] The distances mentioned in (a)(1) and (a)(2) are:

where: RN = A + WN = WB/cos(90°-α) + WN RM = B + WM = WB tan(90°-α) + WM X = safety distance of outer main wheel during turn to the edge of the runway Y = safety distance of outer nose wheel during turn to the edge of the runway Note: Minimum edge safety distances for X and Y are specified in FAA AC 150/5300-13 and ICAO Annex 14, 3.8.3 RN = radius of turn of outer nose wheel RM = radius of turn of outer main wheel WN = distance from aeroplane centre-line to outer nose wheel WM = distance from aeroplane centre-line to outer main wheel WB = wheel base α = steering angle.

RUNWAY SURFACE CONDITION

(a)Operation on runways contaminated with water, slush, snow or ice implies uncertainties with regard to runway friction and contaminant drag and, therefore, to the achievable performance and control of the aeroplane during take-off, since the actual conditions may not completely match the assumptions on which the performance information is based. In the case of a contaminated runway, the first option for the commander is to wait until the runway is cleared. If this is impracticable, he/she may consider a take-off, provided that he/she has applied the applicable performance adjustments, and any further safety measures he/she considers justified under the prevailing conditions.

(b)An adequate overall level of safety will only be maintained if operations in accordance with AMC 25.1591 or equivalent are limited to rare occasions. Where the frequency of such operations on contaminated runways is not limited to rare occasions, the operator should provide additional measures ensuring an equivalent level of safety. Such measures could include special crew training, additional distance factoring and more restrictive wind limitations.