About FC135.ai

FC135.ai answers two kinds of question about US federal aviation regulations: what a rule requires and whether it applies to you, and whether your manual is current against it.

How an answer is produced

  1. Your question is classified. Anything outside those two kinds is refused.
  2. Relevant sections are retrieved from the regulation text we hold.
  3. A language model answers from those sections only.
  4. Every quotation is checked character-for-character against the source. Anything that doesn't match is deleted — and if that leaves the answer without support, the whole answer is replaced with an honest "we can't source this."

What we hold

Verbatim regulation text, fetched from the eCFR Versioner API and refreshed daily:

Regulation 14 CFR — 14 parts
Regulation 49 CFR — 3 parts
FAA guidance 4774 documents — guidance on how to comply, not the rule itself

Current as of 2 Aug 2026.

What we don't hold

FAA guidance — Advisory Circulars, Orders including 8900.1, legal interpretations, SAFOs and InFOs — is not yet collected. Answers cite regulation text only. We would rather say so than let a model fill the gap from memory.

What this is not

Not legal advice. We cite what a regulation says. We do not opine on enforcement, liability, penalties, or what you should do about an incident. These are US federal rules; nothing here speaks to any other jurisdiction.