OPS 1.475
General
(a) An operator shall ensure that the mass of the aeroplane:
(1) at the start of the take-off; or, in the event of in-flight replanning
(2) at the point from which the revised operational flight plan applies, is not greater than the mass at which the requirements of the appropriate subpart can be complied with for the flight to be undertaken, allowing for expected reductions in mass as the flight proceeds, and for such fuel jettisoning as is provided for in the particular requirement.
(b) An operator shall ensure that the approved performance data contained in the aeroplane flight manual is used to determine compliance with the requirements of the appropriate subpart, supplemented as necessary with other data acceptable to the Authority as prescribed in the relevant subpart. When applying the factors prescribed in the appropriate subpart, account may be taken of any operational factors already incorporated in the aeroplane flight manual performance data to avoid double application of factors. ...
OPS 1.515
Landing — dry runways
(a) An operator shall ensure that the landing mass of the aeroplane determined in accordance with OPS 1.475(a) for the estimated time of landing at the destination aerodrome and at any alternate aerodrome allows a full stop landing from 50 ft above the threshold:
(1) for turbo-jet powered aeroplanes, within 60 % of the landing distance available; or
(2) for turbo-propeller powered aeroplanes, within 70 % of the landing distance available; ...
OPS 1.520
Landing — wet and contaminated runways
(a) An operator shall ensure that when the appropriate weather reports or forecasts, or a combination thereof, indicate that the runway at the estimated time of arrival may be wet, the landing distance available is at least 115 % of the required landing distance, determined in accordance with OPS 1.515. ...