Eligible on Demand Operators are provided certain relief from FAR 135.225. Flying an instrument approach to an airport without approved weather reporting (i.e. no altimeter setting) is permitted within certain provisions.

125.225 (b) (2) The latest weather report issued by the weather reporting facility includes a current local altimeter setting for the destination airport. If no local altimeter setting for the destination airport is available, the pilot may use the current altimeter setting provided by the facility designated on the approach chart for the destination airport.