Civil Sonic Boom

FAR 91.817 — Civil Sonic Boom

FAR 91.817 prohibits civil aircraft from exceeding Mach 1 over the U.S. without authorization. Learn the rule, exceptions, and exam tips for pilots.

In Plain English

FAR 91.817 restricts supersonic flight by civil aircraft in the United States. The core rule is simple: you cannot operate a civil aircraft at a true flight Mach number greater than 1 within the U.S. unless you have a specific authorization to exceed Mach 1 issued under FAR 91.818.

The regulation also addresses civil aircraft capable of supersonic flight (where the maximum operating limit speed (M_MO) exceeds Mach 1) operating to or from U.S. airports. For these aircraft:

The flight crew must have flight limitations information that ensures flights entering or leaving the U.S. will not cause a sonic boom to reach the surface within the United States; and
The operator must either comply with those flight limitations or operate under an authorization issued under § 91.818.

Why it matters operationally: sonic booms can damage structures, disturb people and wildlife, and create liability. The FAA controls supersonic operations tightly to prevent surface-level booms over U.S. territory.

Regulation Text

14 CFR § 91.817

§ 91.817 Civil aircraft sonic boom. (a) No person may operate a civil aircraft in the United States at a true flight Mach number greater than 1 except in compliance with conditions and limitations in an authorization to exceed Mach 1 issued to the operator in accordance with § 91.818. (b) In addition, no person may operate a civil aircraft for which the maximum operating limit speed Mexceeds a Mach number of 1, to or from an airport in the United States, unless— (1) Information available to the flight crew includes flight limitations that ensure that flights entering or leaving the United States will not cause a sonic boom to reach the surface within the United States; and (2) The operator complies with the flight limitations prescribed in paragraph (b)(1) of this section or complies with conditions and limitations in an authorization to exceed Mach 1 issued in accordance with § 91.818. [Docket 18334, 54 FR 34321, Aug. 18, 1989, as amended by Amdt. 91-362, 86 FR 3792, Jan. 15, 2021] (Approved by the Office of Management and Budget under control number 2120-0005)

Oral Exam Questions a DPE Might Ask

Q1Can a civil aircraft fly faster than the speed of sound over the United States?

Not without specific FAA authorization. Per FAR 91.817, no person may operate a civil aircraft in the U.S. at a true flight Mach number greater than 1 except under an authorization to exceed Mach 1 issued in accordance with FAR 91.818.

Q2If you're flying a supersonic-capable civil aircraft into a U.S. airport, what must be true about your operation?

Under FAR 91.817(b), the flight crew must have flight limitation information ensuring no sonic boom reaches the U.S. surface, and the operator must either comply with those limitations or operate under a Mach 1 authorization issued under FAR 91.818.

Q3What is the operational concern that FAR 91.817 is designed to prevent?

FAR 91.817 is designed to prevent sonic booms from reaching the surface within the United States during civil supersonic operations, by restricting flight above Mach 1 and requiring flight limitations or specific authorization.

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Related Sections in Part 91

§ 91.1

Part 91 Applicability