Definition
A method of transmitting weather charts and other graphical aviation products in digital form, allowing them to be received, stored, and displayed electronically rather than printed on traditional fax paper. DFAX products include surface analysis charts, prognostic charts, and other graphical weather information distributed by the National Weather Service for aviation use.
Plain English
A digital version of a fax — a way of sending weather charts and similar pictures electronically so pilots and briefers can view them on a screen.
Context Anchor
Seen in FAA acronym lists and older aviation weather or information-system references, especially where charts or written notices are transmitted electronically.
Derivation
‘Facsimile’ comes from the Latin ‘fac simile,’ meaning ‘make alike’ — that is, an exact copy. ‘Digital’ simply means the copy is sent as electronic data instead of as a printed image, so the chart arrives on a screen rather than on paper.
Why Pilots Care
Gives pilots access to detailed graphical weather information during preflight planning without requiring physical delivery.
Analogy
It is like sending a scanned page to someone so they can view or print the same page at another location.
Intuition Check
Do not read DFAX as a flight procedure, navigation fix, or clearance term. It refers to a method of copying and sending information electronically.
Example Sentence 1
The surface analysis chart in the briefing package was distributed as a DFAX product from the National Weather Service.
Example Sentence 2
DFAX delivered the updated radar summary directly to the flight planning station.