Recommended Practice RP4 - Rotorcraft VFR Weather Minimums Revised May 3, 2006   The AMSAC strongly recommends that all VFR flight operations be conducted under no less than Part 135 standards, as defined by Operations Specifications AO21. AMSAC also recommends that Part 135 Operators and Air Medical Programs adapt their local VFR weather minimums and local flying areas to any unique terrain, weather reporting, regional phenomenon and ambient light conditions appropriate to each base, pilot, and aircraft capability. The following factors should be considered when establishing a local flying area and weather minimums.   Local Flying area:This area should be well defined by geographic or man-made features and limited to those areas in which flights have adequate ambient light at night, minimal terrain variation, and limited or easily visualized obstacles or hazards. This area is one in which the pilots and crews are very familiar and navigation and hazard avoidance are uncomplicated. Safe forced or precautionary landing areas should be readily available. Cross country flights are those outside of the local flying area.   Ceiling and visibility minimums: We recommend that the baseline for ceiling and weather minimums are those currently published as CAMTS standards.   Ceiling: Flights over mountainous or hazardous terrain (as defined below) should have higher ceiling requirements unless they are within a well defined local flying area. Recommended ceilings for a route through mountainous terrain should be at least 1000 feet (Day) and 2000 feet (night) over the highest terrain within three nautical miles of the route of flight centerline.   Visibility: Flights over mountainous terrain should have higher visibility minimums than flights over flat terrain. Recommended visibility for a route through mountainous terrain should be at least three miles (day) and five miles (night) and be flown over the highest terrain within three nautical miles of the route of flight centerline.   Mountainous or hazardous terrain: Mountainous terrain (as defined for this RP) is terrain over which a route (or within three miles of the route) varies in elevation more than 1000 feet. Hazardous terrain is defined as terrain which has significant obstacles, antennas, power lines and such within three miles of the route or has minimal visual surface reference or subtle elevation changes.   Any consideration of minimums should assess the following factors when determining local base minimums: IFR-VFR-night capability (aircraft, NVG, avionics, training, pilot, currency, and facilities), availability and dependability of weather forecasting and observations (enroute and terminal), local weather variability (micro-climates), and/or terrain. Pilots’ minimums should be increased if not locally familiar, in new or different aircraft, or not comfortable or current per local policy. It is recommended that regional aviation safety councils work to standardize local area minimums to avoid like programs using minimums based on competition rather than criteria suggested above.   Minimums are never to be considered as mandatory launch criteria and the final authority for any flight is always the pilot-in-command. Any crewmember who is uncomfortable with launching on or continued flight into conditions perceived as hazardous has the absolute right to request that the pilot return to safer conditions immediately.     Recommended Practices are published under the direction of the Air Medical Safety Advisory Council (AMSAC). RPs are a medium for discussion of aviation and medical operational safety pertinent to the Air Medical Community. RPs are not intended to replace corporate judgment, Federal Aviation Regulations, Company Operations Manuals, or Organizational SOPs. Suggestions for subject matter are cordially invited. Change 1 is underlined material 05/03/2006 back