14 CFR § 25.1505 - Maximum operating limit speed.

---
identifier: "/us/cfr/t14/s25.1505"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "14 CFR § 25.1505 - Maximum operating limit speed."
title_number: 14
title_name: "Aeronautics and Space"
section_number: "25.1505"
section_name: "Maximum operating limit speed."
chapter_name: "FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
subchapter_number: "C"
subchapter_name: "AIRCRAFT"
part_number: "25"
part_name: "AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 106(f), 106(g), 40113, 44701, 44702 and 44704; Pub. L. 115-254, 132 Stat 3281 (49 U.S.C. 44903 note)."
regulatory_source: "Docket No. 5066, 29 FR 18291, Dec. 24, 1964, unless otherwise noted."
cfr_part: "25"
---


# 25.1505 Maximum operating limit speed.

The maximum operating limit speed (*V*<sub>MO</sub>/*M*<sub>MO</sub> airspeed or Mach Number, whichever is critical at a particular altitude) is a speed that may not be deliberately exceeded in any regime of flight (climb, cruise, or descent), unless a higher speed is authorized for flight test or pilot training operations. *V*<sub>MO</sub>/*M*<sub>MO</sub> must be established so that it is not greater than the design cruising speed *V*<sub>C</sub> and so that it is sufficiently below *V*<sub>D</sub>/*M*<sub>D</sub> or *V*<sub>DF</sub>/*M*<sub>DF,</sub> to make it highly improbable that the latter speeds will be inadvertently exceeded in operations. The speed margin between *V*<sub>MO</sub>/*M*<sub>MO</sub> and *V*<sub>D</sub>/*M*<sub>D</sub> or *V*<sub>DF</sub>*M/*<sub>DF</sub> may not be less than that determined under § 25.335(b) or found necessary during the flight tests conducted under § 25.253.

[Amdt. 25-23, 35 FR 5680, Apr. 8, 1970]