Definition
A coloring agent added to aviation fuel so that each grade can be identified visually by its distinct color. Common examples include blue for 100LL avgas, green for 100/130 avgas, and clear or straw-colored for Jet A.
Plain English
A dye mixed into aviation fuel to give each type its own color, so a pilot can tell at a glance which fuel is in the tank.
Context Anchor
Seen during preflight fuel checks, especially when draining a small fuel sample and checking its color, clarity, and smell.
Why Pilots Care
Correct dye color confirms the right fuel grade; visible staining reveals leaks before flight.
Intuition Check
Do not assume fuel dye is just for appearance. In aviation, the color is used as an identification clue, but color alone should not be the only fuel check.
Example Sentence 1
During preflight, the pilot drained a fuel sample and confirmed the blue color of 100LL before continuing.
Example Sentence 2
Before fueling, the pilot checked that the truck dispensed fuel with the correct dye color for the aircraft.