Hi, does anyone understands the logic of why you could dispatch to a runway that is contaminated as long as you have 2 alternates planned. But you are not allowed to apply this logic to a runway that is dry/wet.
(both under most favorable, no wind conditions)
Flight prep instructionsLanding
The maximum landing weight of the aeroplane for the destination, destination alternate, fuel ERA and re-dispatch or re-clearance aerodrome(s) must be limited as follows: 1. Maximum weight for the elevation and temperature at the ETA resulting from approach climb, landing climb or maximum weight for operations with Decision Height (DH) below 200 ft. Possible resulting limitations are published in OM Part B and OM Part C3. 2. Maximum weight for the elevation, forecasted wind and expected runway condition at the Estimated Time of Arrival (wet, dry or contaminated), the aeroplane shall: a. Firstly, land on the most favourable runway (normally the longest) in still air. Regardless of the wind conditions, the maximum landing mass for an aerodrome/aeroplane configuration at a particular aerodrome cannot be exceeded; b. Secondly, land on the runway most likely to be assigned considering the probable wind speed and direction and the ground handling characteristics of the aeroplane and considering other aids such as landing aids and terrain. The expected wind, ATC and noise abatement procedures, may indicate the use of a different runway. These factors may result in a lower landing mass than permitted under (a) in which case dispatch should be based on this lesser mass.
3. If unable to comply with point (2)(a) above for the destination aerodrome where the appropriate weather reports or forecasts indicate that the runway at the Estimated Time of Arrival may be dry or wet and where a landing depends upon a specific wind component, the aeroplane shall not be dispatched.
4. If unable to comply with point (2)(a) above for the destination aerodrome where the appropriate weather reports or forecasts indicate that the runway at the Estimated Time of Arrival may be contaminated and where a landing depends upon a specific wind component, the aeroplane shall only be dispatched if two alternate aerodromes are selected which permits full compliance with all landing requirements above.
5. When the appropriate weather reports or forecasts indicate that the runway at the estimated time of arrival may be contaminated, the LDA shall be at least the landing distance determined in accordance with OM Part B (FCOM) Performance sections for wet runways, or at least 115 % of the landing distance determined in accordance with approved contaminated landing distance data in OM Part B (FCOM), whichever is greater.
6. If unable to comply with (2)(b) above for the destination aerodrome, the aeroplane may be dispatched if one destination alternate aerodrome is selected which permits full compliance with all landing requirements above and the dispatch landing performance requirements specified in the FCOM. the FCOM. Points 2 to 6 are summarized in the runway suitability check table below:
Runway At time of dispatch, check for ETA
Most favorable, no wind | and | Most likely, probably wind
If unable to comply:
Dry No dispatch | 1 Alternate
Wet No dispatch | 1 Alternate
Contaminated 2 Alternates | 1 Alternate