FAR 21.700 — Lavatory Oxygen Systems
FAR 21.700 applies SFAR No. 111 lavatory oxygen system requirements (§121.1500) to Part 21 certification. What pilot students need to know.
FAR 21.700 is a short cross-reference rule. It states that the requirements of § 121.1500 — known as SFAR No. 111, Lavatory Oxygen Systems — also apply to Part 21.
In plain terms:
- Part 21 covers the certification procedures for aircraft products and parts (type certificates, production approvals, airworthiness certificates, etc.).
- SFAR 111 is a Special Federal Aviation Regulation that imposes safety requirements on chemical oxygen generators installed in aircraft lavatories, originally issued in response to security concerns about lavatory oxygen systems being used to start fires.
- By incorporating § 121.1500 into Part 21, the FAA ensures that manufacturers and certification applicants — not just air carriers operating under Part 121 — must comply with the lavatory oxygen system requirements during the design, production, and certification process.
Why it matters operationally: While line pilots rarely interact with this rule directly, it explains why many transport-category aircraft have disabled or modified lavatory oxygen systems. As a pilot, you should know the lavatories may not have functional supplemental oxygen, and brief passengers and cabin crew accordingly.
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?