SAE ARP 5119:2013-01-15

The recommendations of this document apply to such aircraft as are able to perform both normal angle and steep IMC approaches, the latter being defined as those approaches having a final approach segment angle greater than 4°. Such aircraft can include both conventional and STOL fixed-wing aircraft, commercial air transport and/or utility and normal category helicopters, compound helicopters and powered lift vehicles (tiltrotors, tiltfans, tiltwings, etc.).