Definition
A precision optical instrument mounted on a tripod, consisting of a telescope that can be rotated horizontally and vertically, used to measure angles and establish straight reference lines. In aircraft maintenance, it is used during airframe alignment and rigging checks to verify that structural components, control surfaces, and reference points are positioned correctly relative to one another.
Plain English
A telescope on a tripod that lets a technician sight along an exact straight line and measure angles very accurately. It is used to check that parts of the aircraft line up the way they should.
Context Anchor
Seen in airframe maintenance, especially when checking aircraft alignment, structure position, or large-part setup.
Derivation
From the Latin transitus, meaning 'a passing across.' The instrument is named for the way its telescope can be 'transited' — flipped over on its horizontal axis — to sight a line in the opposite direction without disturbing the setup. That ability to reverse the sight line is what makes it useful for checking straightness and alignment.
Why Pilots Care
Accurate use prevents misalignment of wings, stabilizers, or control surfaces that could affect flight handling and safety.
Intuition Check
A surveyor’s transit is not about transportation or moving through an airport. Here, transit means a precise sighting instrument used to measure lines and angles.
Example Sentence 1
The technician set up a surveyor's transit on the hangar floor to verify the wing's incidence angle during rigging.
Example Sentence 2
Using the surveyor’s transit, the mechanic confirmed the horizontal stabilizer was level before final torqueing.