Regulation Text
(a) Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).
(b) Unless otherwise authorized or required by ATC, no person may operate an aircraft at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of a Class C or Class D airspace area at an indicated airspeed of more than 200 knots (230 mph.). This paragraph (b) does not apply to any operations within a Class B airspace area. Such operations shall comply with paragraph (a) of this section.
(c) No person may operate an aircraft in the airspace underlying a Class B airspace area designated for an airport or in a VFR corridor designated through such a Class B airspace area, at an indicated airspeed of more than 200 knots (230 mph).
(d) If the minimum safe airspeed for any particular operation is greater than the maximum speed prescribed in this section, the aircraft may be operated at that minimum speed.
[Docket 18334, 54 FR 34292, Aug. 18, 1989, as amended by Amdt. 91-219, 55 FR 34708, Aug. 24, 1990; Amdt. 91-227, 56 FR 65657, Dec. 17, 1991; Amdt. 91-233, 58 FR 43554, Aug. 17, 1993]
Research Notes
Section 91.117 imposes maximum airspeed limits in specific airspace and altitude bands. These are hard numbers that every pilot must know because exceeding them is a clean rule violation regardless of intent.
The 250-knot rule (paragraph a): Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 mph). This is the universal speed limit for the lower atmosphere. Above 10,000 MSL there is no Part 91 airspeed limit (subject to aircraft and route-of-flight limitations).
The 200-knot rule for Class B underlying — paragraph (c): Below 2,500 feet AGL within 4 nautical miles of the primary airport of a Class B airspace area, the speed limit is 200 KIAS — INSIDE Class B too if specifically designated by the Administrator. The full Class B speed rule reads: 200 KIAS in airspace UNDERLYING Class B and in VFR corridors through Class B.
The 200-knot rule for Class C/D — paragraph (b): Below 2,500 feet AGL within 4 NM of the primary airport of a Class C or Class D airspace area, the speed limit is 200 KIAS. This catches the typical traffic pattern environment at most towered airports.
The aircraft-can't-comply exception (paragraph d): If the minimum safe airspeed for the aircraft (e.g., a fighter on approach, an experimental, a high-performance turbine) is GREATER than the 250 or 200 KIAS limit, the aircraft may be operated at that minimum safe airspeed. This is not a 'go faster because I want to' clause — it requires that the aircraft cannot be safely operated below the stated limit.
ATC speed assignments: ATC may assign speeds. When ATC assigns a speed greater than 250 KIAS below 10,000 MSL, the PIC must comply with the assigned speed — § 91.117 is overridden by the ATC instruction (per § 91.117(a)'s 'otherwise authorized' clause and the principle of ATC authority within controlled airspace).
Common enforcement scenarios: Departing a Class C or B airport at high indicated airspeed in the climb, descending into a Class B underlying area at jet-cruise speeds, low-altitude high-speed overflight of Class D airports. The 200 KIAS limit catches a lot of business jet pilots who descend through 2,500 AGL near a Class D and don't slow down in time.
Reference: AIM 3-2 on Controlled Airspace speed limits. FAA-H-8083-25 (PHAK) Chapter 15 on airspace.
Amendment History
Amendment History Coming Soon
Every time this regulation changes, we'll record it here — the date, what was amended, and a plain-English summary of what shifted.