Definition
The distance between the centerlines of the two main landing gear wheels (or wheel groups) of an aircraft, measured across the airframe perpendicular to the longitudinal axis.
Plain English
How far apart the two main wheels are, side to side, when you look at the aircraft from the front or back.
Context Anchor
Seen in aircraft design and ground-handling discussions, especially when considering how stable an airplane is while taxiing, taking off, or landing.
Derivation
‘Track’ here comes from the same idea as a vehicle’s ‘track width’ — the gap between the left and right wheels. The word traces back to Old French ‘trac’ meaning a path or trail left by wheels.
Why Pilots Care
A wider track improves resistance to tipping during turns or crosswind taxiing.
Analogy
It is like the stance of a person’s feet. Feet spread farther apart give better balance; feet close together make tipping sideways easier.
Intuition Check
“Track” does not mean a course, route, or runway path here. It means the left-to-right spacing between the main landing gear contact points.
Example Sentence 1
The aircraft’s wide main landing gear track width helped keep it stable during the gusty crosswind landing.
Example Sentence 2
A narrow main landing gear track width requires extra care during sharp turns to avoid tipping.