Definition
Movable markers placed around the rim of the airspeed indicator (or set electronically on a digital airspeed tape) that the pilot positions at specific reference speeds so those speeds can be seen at a glance during flight.
Plain English
Small pointers you set on the airspeed display to mark the speeds you want to fly at, so you can see them quickly without having to remember the exact numbers.
Context Anchor
Seen on analog airspeed indicators with movable markers and on glass cockpit displays with settable speed references.
Derivation
The term 'bug' comes from older aviation and engineering use, where a small adjustable marker on a dial was nicknamed a 'bug' because it sat on the face of the instrument like a tiny insect. The name stuck even after the markers became digital.
Why Pilots Care
They give pilots an immediate visual reference to key speeds during high-workload phases without looking away from the instruments.
Analogy
They are like putting small reminder marks on a car’s speedometer before a trip, so you can see your target speeds without rechecking a list.
Intuition Check
“Bugs” does not mean defects or computer errors here. In this context, bugs are intentional markers used to highlight important airspeeds.
Example Sentence 1
Before takeoff, the pilot set the airspeed bugs to mark rotation and initial climb speeds.
Example Sentence 2
She adjusted the bugs for the published go-around speed during the missed approach briefing.