The operator shall select at least two destination alternate aerodromes for each IFR flight and specify them in the OFP when-
(a) the appropriate weather reports or forecasts for the destination aerodrome, or any combination thereof, indicate that during a period commencing one hour before and ending one hour after the estimated time of arrival, the weather conditions will be below the applicable planning minima; or
(b) meteorological information is not available at the destination aerodrome.