Means to discreetly notify a flightcrew

This regulation requires airlines operating passenger flights with lockable cockpit doors to have an FAA-approved system that lets flight attendants secretly alert the pilots about suspicious activity or security problems in the cabin. The key word is "discreetly"—the system must allow cabin crew to communicate a threat without other passengers noticing.

In practice, this typically means a specific interphone code, button sequence, or other covert signal that flight attendants can use to warn pilots of potential hijackers, unruly passengers, or other security concerns without tipping off the threat. This gives the flight crew advance warning to secure the cockpit, coordinate with authorities, or take other protective measures.

The requirement applies to all passenger-carrying operations that need lockable cockpit doors (essentially all Part 121 passenger flights since 9/11), but specifically excludes all-cargo operations where there are no passengers in the cabin to pose such threats.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*