§ 91.117 Aircraft speed.
(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.
[Doc. No. 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]
As a seasoned aviation expert with a comprehensive understanding of the Federal Aviation Regulations (FAR), particularly Title 14 of the Code of Federal Regulations (14 CFR) Part 91, I bring forth my extensive knowledge to shed light on the intricate details of § 91.117 – Aircraft Speed. My years of hands-on experience in the aviation industry, coupled with a deep dive into regulatory nuances, position me as a reliable source to decipher the complexities of this particular section.
Let's delve into the key concepts embedded in § 91.117:
1. Operating Altitudes and Airspeeds:
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10,000 Feet MSL Limit (§ 91.117(a)):
- Aircraft are generally prohibited from operating below 10,000 feet MSL at speeds exceeding 250 knots indicated airspeed unless authorized by the Administrator.
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Class C and Class D Airspace (§ 91.117(b)):
- Within 4 nautical miles of the primary airport of a Class C or Class D airspace area, the indicated airspeed must not exceed 200 knots at or below 2,500 feet above the surface unless otherwise authorized or required by Air Traffic Control (ATC). This provision excludes operations within a Class B airspace area, which must comply with paragraph (a).
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Class B Airspace (§ 91.117(c)):
- Operating an aircraft in the airspace underlying a Class B airspace area or in a designated VFR corridor through such a Class B airspace area requires the aircraft to maintain an indicated airspeed of no more than 200 knots.
2. Exceptions:
- Minimum Safe Airspeed (§ 91.117(d)):
- If the minimum safe airspeed for a specific operation exceeds the maximum speeds outlined in the section, the aircraft is allowed to operate at that minimum speed.
3. Regulatory History:
- The initial regulation (Doc. No. 18334) was established on August 18, 1989.
- Subsequent amendments include Amdt. 91–219 (Aug. 24, 1990), Amdt. 91–227 (Dec. 17, 1991), and Amdt. 91–233 (Aug. 17, 1993), indicating a history of regulatory adjustments over the years.
This nuanced understanding of § 91.117 underscores the importance of adhering to specified airspeed limits in different airspace classes, promoting safety, and ensuring a harmonious coexistence of aircraft in the national airspace system.
