What minimum altitude must IFR aircraft maintain in designated mountainous regions in areas 1 and 5?

In designated mountainous regions, IFR (Instrument Flight Rules) aircraft are required to adhere to specific minimum altitude criteria to ensure safety. For areas classified as mountainous, the regulation mandates that aircraft maintain a minimum altitude of 2000 feet above the highest obstacle within a horizontal distance of 5 nautical miles from the course they are flying.

This is crucial because mountainous terrain can present significant hazards to flight, making it imperative that aircraft operate at sufficient elevations to avoid obstacles such as peaks, ridges, and other elevated terrain features, especially in adverse weather conditions where visibility may be limited. Maintaining this altitude helps provide a buffer that enhances safety during instrument flight operations.

In summary, the requirement of 2000 feet at a lateral distance of 5 nautical miles is designed to promote safe separation from mountainous terrain and provide pilots with a margin of safety as they navigate through these challenging airspaces.