B.4 Standard En Route Alternate Weather Minima

The following are established for flight planning and dispatch purposes in ETOPS operations:

A particular airport may be considered a suitable airport for flight planning and dispatch purposes for ETOPS operations if it meets the criteria of paragraphB.3 of this Appendix and has one of the following combinations of instrument approach capabilities and en route alternate airport weather minima at the time of the particular operation.

FACILITIES AVAILABLE AT SUITABLE ALTERNATE CEILING VISIBILITY
2 or more useable precision approaches each providing straight-in minima to separate suitable runways. (Two separate landing surfaces) 400feet, or 200feet above the lowest useable HAT, whichever is higher. 1s.m., or ½s.m. more than the lowest useable visibility limit, whichever is greater.
1useable precision approach. 600feet, or 300feet above the lowest authorized HAT/HAA, whichever is higher. 2s.m., or 1s.m more than the lowest published landing visibility, whichever is greater.
1useable non-precision approach. 800feet, or 300feet above the lowest authorized HAT/HAA, whichever is higher. 2s.m., or 1s.m more than the lowest published landing visibility, whichever is greater.

See A.I.P. Canada, GEN section for conversion factors/tables.

Note: Weather forecasts that contain the term BECMG, TEMPO or PROB may be used to determine the weather suitability of an aerodrome as an alternate provided that:

  1. where the conditions are forecast to improve, the forecast BECMG condition shall be considered to be applicable as of the end of the BECMG time period, and these conditions shall not be below the published alternate minima requirements for that aerodrome; and,
  2. where the conditions are forecast to deteriorate, the forecast BECMG condition shall be considered to be applicable as of the start of the BECMG time period, and these conditions shall not be below the published alternate minima requirements for that aerodrome; and,
  3. the forecast TEMPO condition shall not be below the published alternate minima requirements for that aerodrome; and,
  4. the forecast PROB condition shall not be below the appropriate landing minima for that aerodrome. Where a condition is forecast as "PROB", provided the probability per cent factor is less than 40per cent, it is not limiting. However the Pilot-In-Command will exercise good aviation judgment in assessing the overall "PROB" conditions.
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