CAT.POL.A.310 Take-off obstacle clearance – multi-engined aeroplanes

TAKE-OFF FLIGHT PATH — VISUAL COURSE GUIDANCE NAVIGATION

(a)In order to allow visual course guidance navigation, the weather conditions prevailing at the time of operation, including ceiling and visibility, should be such that the obstacle and/or ground reference points can be seen and identified. For VFR operations by night, the visual course guidance should be considered available when the flight visibility is 1 500 m or more.

(b)The operations manual should specify, for the aerodrome(s) concerned, the minimum weather conditions that enable the flight crew to continuously determine and maintain the correct flight path with respect to ground reference points so as to provide a safe clearance with respect to obstructions and terrain as follows:

(1)the procedure should be well defined with respect to ground reference points so that the track to be flown can be analysed for obstacle clearance requirements;

(2)the procedure should be within the capabilities of the aeroplane with respect to forward speed, bank angle and wind effects;

(3)a written and/or pictorial description of the procedure should be provided for crew use; and

(4)the limiting environmental conditions should be specified (e.g. wind, cloud, visibility, day/night, ambient lighting, obstruction lighting).

TAKE-OFF FLIGHT PATH CONSTRUCTION

(a)For demonstrating that the aeroplane clears all obstacles vertically, a flight path should be constructed consisting of an all-engines segment to the assumed engine failure height, followed by an engine-out segment. Where the AFM does not contain the appropriate data, the approximation given in (b) may be used for the all-engines segment for an assumed engine failure height of 200 ft, 300 ft, or higher.

(b)Flight path construction

(1)All-engines segment (50 ft to 300 ft) The average all-engines gradient for the all-engines flight path segment starting at an altitude of 50 ft at the end of the take-off distance ending at or passing through the 300 ft point is given by the following formula:

The factor of 0.77 as required by CAT.POL.A.310 is already included where: Y300 = average all-engines gradient from 50 ft to 300 ft; YERC = scheduled all engines en-route gross climb gradient; VERC = en-route climb speed, all engines knots true airspeed (TAS); V2 = take-off speed at 50 ft, knots TAS;

(2)All-engines segment (50 ft to 200 ft) This may be used as an alternative to (b)(1) where weather minima permit. The average all-engines gradient for the all-engines flight path segment starting at an altitude of 50 ft at the end of the take-off distance ending at or passing through the 200 ft point is given by the following formula:

The factor of 0.77 as required by CAT.POL.A.310 is already included where: Y200 = average all-engines gradient from 50 ft to 200 ft; YERC = scheduled all engines en-route gross climb gradient; VERC = en-route climb speed, all engines, knots TAS; V2 = take-off speed at 50 ft, knots TAS.

(3)All-engines segment (above 300 ft) The all-engines flight path segment continuing from an altitude of 300 ft is given by the AFM en-route gross climb gradient, multiplied by a factor of 0.77.

(4)The OEI flight path The OEI flight path is given by the OEI gradient chart contained in the AFM.

OBSTACLE CLEARANCE IN LIMITED VISIBILITY

(a)Unlike the Certification Specifications applicable for performance class A aeroplanes, those for performance class B aeroplanes do not necessarily provide for engine failure in all phases of flight. It is accepted that performance accountability for engine failure need not be considered until a height of 300 ft is reached.

(b)The weather minima given up to and including 300 ft imply that if a take-off is undertaken with minima below 300 ft, an OEI flight path should be plotted starting on the all-engines take-off flight path at the assumed engine failure height. This path should meet the vertical and lateral obstacle clearance specified in CAT.POL.A.310. Should engine failure occur below this height, the associated visibility is taken as being the minimum that would enable the pilot to make, if necessary, a forced landing broadly in the direction of the take-off. At or below 300 ft, a circle and land procedure is extremely inadvisable. The weather minima provisions specify that, if the assumed engine failure height is more than 300 ft, the visibility should be at least 1 500 m and, to allow for manoeuvring, the same minimum visibility should apply whenever the obstacle clearance criteria for a continued take-off cannot be met.

TAKE-OFF FLIGHT PATH CONSTRUCTION

(a)This GM provides examples to illustrate the method of take-off flight path construction given in AMC2 CAT.POL.A.310. The examples are based on an aeroplane for which the AFM shows, at a given mass, altitude, temperature and wind component the following performance data: factored take-off distance – 1 000 m; take-off speed, V2 – 90 kt; en-route climb speed, VERC – 120 kt; en-route all-engines climb gradient, YERC – 0.2; en-route OEI climb gradient, YERC-1 – 0.032.

(1)Assumed engine failure height 300 ft The average all-engines gradient from 50 ft to 300 ft may be read from Figure 1 or calculated with the following formula:

The factor of 0.77 as required by CAT.POL.A.310 is already included where: Y300 = average all-engines gradient from 50 ft to 300 ft; YERC = scheduled all engines en-route gross climb gradient; VERC = en-route climb speed, all engines knots TAS; and V2 = take-off speed at 50 ft, knots TAS. Figure 1 Assumed engine failure height 300 ft [Figure or form omitted from this preview — available in the Avioverse workspace library.]

(2)Assumed engine failure height 200 ft The average all-engines gradient from 50 ft to 200 ft may be read from Figure 2 or calculated with the following formula:

The factor of 0.77 as required by CAT.POL.A.310 is already included where: Y200 = average all-engines gradient from 50 ft to 200 ft; YERC = scheduled all engines en-route gross gradient; VERC = en-route climb speed, all engines, knots TAS; and V2 = take-off speed at 50 ft, knots TAS.

Figure 2 Assumed engine failure height 200 ft [Figure or form omitted from this preview — available in the Avioverse workspace library.]

(3)Assumed engine failure height less than 200 ft Construction of a take-off flight path is only possible if the AFM contains the required flight path data.

(4)Assumed engine failure height more than 300 ft The construction of a take-off flight path for an assumed engine failure height of 400 ft is illustrated below.

Figure 3 Assumed engine failure height less than 200 ft [Figure or form omitted from this preview — available in the Avioverse workspace library.]