FAR 91.821 — Supersonic Noise Limits
FAR 91.821 explains noise limits for civil supersonic airplanes operating in the U.S., including the Concorde exception and Stage 2 compliance under Part 36.
FAR 91.821 sets the noise rules for civil supersonic airplanes operating in the United States. In plain terms, if you want to fly a civil supersonic jet inside U.S. airspace, the aircraft must meet the Stage 2 noise limits of 14 CFR Part 36 as those limits stood on October 13, 1977, including any applicable trade-off provisions (which let manufacturers offset noise on one measurement point against margin on another).
There is one narrow exception:
- Concorde airplanes that already had flight time before January 1, 1980 are grandfathered and do not have to comply.
Why it matters operationally:
- It limits which supersonic designs can legally operate in U.S. airspace.
- It ties civil supersonic operations to a specific historical noise standard, which is why new supersonic designs must be engineered with these limits in mind.
- For today's pilots, it's mostly a regulatory awareness item — but expect a DPE to know it exists when discussing Subpart I (Operating Noise Limits).
Five FAA-written-style questions. Instant explanations, every answer cites its source — no account needed.
You are flying VFR in Class E airspace at 8,500 feet MSL during the day. What are your minimum visibility and cloud clearance requirements?