Definition
Facsimile equipment is a device that scans a printed page and transmits an exact copy of it electronically to a receiving machine, which prints a duplicate at the other end. In aviation, fax machines have historically been used at flight service stations, dispatch offices, and FBOs to send and receive weather charts, NOTAMs, flight plans, and other paperwork between facilities.
Plain English
A machine that sends a copy of a paper document over a phone line to another machine, which prints out the same document on the other end.
Context Anchor
Seen in FAA acronym, abbreviation, and NOTAM contraction lists, especially in references to older or backup ways of sending aviation information.
Derivation
From the Latin 'fac simile,' meaning 'make alike' or 'make similar.' That is exactly what the machine does — it makes a similar copy of the original page at a distant location.
Why Pilots Care
If FAX appears in an aviation notice or reference, it is pointing to the equipment or system used to send or receive copied documents, not to a flight maneuver or aircraft system.
Intuition Check
Do not read FAX here as just the document being sent. In this FAA listing, FAX means the equipment or system used to send or receive the copy.
Example Sentence 1
The flight school received the student's medical paperwork by FAX from the AME's office.
Example Sentence 2
When the electronic system failed, the crew used FAX to receive the revised flight release.