RELEVANT FAR/AIM DISCUSSION:
[91.123(A), 91.155, 91.157, 91.169(D), 121.649, 135.205, AIM 5-1-15, 5-4-23, FAA-H-8083-16, OPSPEC C077]
1. You may cancel IFR with ATC at any time in VFR conditions below 18,000 feet. (An exception is when flying in a special flight rules area, such as the Washington, D.C., SFRA, which requires you to be flying on an IFR of VFR SFRA flight plan.)
2. You may cancel with ATC or FSS upon completing a flight (on the ground).
3. Do not cancel in the air while on approach to a surface-based Class E airport unless the reported weather meets the basic VFR weather requirements of 91.155: visibility — 3 sm; cloud clearance — 500 feet below, 1,000 feet above, 2,000 feet horizontally. 91.155(c): Except as provided in §91.157 [Special VFR], no…
