1. The Minimum Safe Altitude specified in 14 CFR part 91 for various aircraft operations. 2. Altitudes depicted on approach charts or departure procedure (DP) graphic charts which provide at least 1,000 feet of obstacle clearance for emergency use. Minimum Safe Altitude (MSA) provides at least 1,000 feet of obstacle clearance within a 25-mile radius of the navigation facility, waypoint, or airport reference point upon which the MSA is predicated. MSAs are for emergency use only and do not necessarily assure acceptable navigational signal coverage. Emergency Safe Altitude (ESA) provides at least 1,000 feet of obstacle clearance in nonmountainous areas and 2,000 feet in designated mountainous areas within a 100-mile radius of the navigation facility or waypoint used as the ESA center.
Source FAA Pilot/Controller Glossary · checked 2026-08-25