Definition
A small initial hole drilled into a workpiece to guide a larger drill bit, fastener, or cutting tool to its intended location. The pilot hole keeps the final hole accurately positioned and prevents the larger tool from wandering across the surface.
Plain English
A small starter hole drilled first so that a bigger drill or screw goes in exactly where you want it.
Context Anchor
Seen in aircraft maintenance when drilling sheet metal, fitting parts, or preparing a location for a screw or rivet.
Derivation
From the word 'pilot,' meaning one who guides. The hole 'pilots' or guides the larger tool to the right spot, just as a pilot guides a ship into harbour.
Why Pilots Care
An accurately placed pilot hole is the difference between a clean, properly aligned fastener and a misdrilled hole that may weaken the structure or require a costly repair.
Intuition Check
Pilot here does not mean the person flying the aircraft. It means a guide made first so the next hole or piece of hardware goes where it should.
Example Sentence 1
Before driving the rivet, the technician drilled a pilot hole to make sure the final hole would line up with the underlying structure.
Example Sentence 2
Pilot holes were marked along the spar so the final fastener pattern would line up correctly.