Definition
A clear-sided fuel sampling container, typically made of glass or clear plastic, used during preflight to draw a sample of fuel from each tank sump and drain so the pilot can visually inspect it for water, sediment, and correct fuel grade by color.
Plain English
A see-through cup or jar you use to catch a small amount of fuel from the airplane so you can look at it and check that it is clean, water-free, and the right type.
Context Anchor
Used during the preflight inspection when the pilot drains a small fuel sample from the aircraft’s fuel drains.
Derivation
Transparent comes from the Latin trans- (through) and parere (to appear) -- literally 'appearing through.' The container has to let light pass through it so the pilot can see what is actually inside the fuel sample.
Why Pilots Care
Contaminated fuel can cause engine failure; the transparent container makes contamination immediately visible so the pilot can take corrective action.
Intuition Check
Do not assume any container is good enough. In this context, transparent means clear enough to see the fuel’s color and any water or dirt in the sample.
Example Sentence 1
During preflight, the pilot drained a sample from each wing sump into a transparent container and checked it for water beads at the bottom.
Example Sentence 2
After swirling the fuel in the transparent container, no sediment or water layer appeared at the bottom.