Plain English Meaning
A version of an aircraft that normally carries only one pilot but has been built with a second seat so an instructor can fly along and teach a student how to operate that aircraft.
Full Definition
Variants of a single-seat military aircraft that have been modified to include a second seat, typically used for pilot instruction, conversion training, or check rides on that specific aircraft type.
Context Anchor
Seen in discussions of training aircraft, simulators, and electronic learning tools that let an instructor guide or monitor a learner.
Why Pilots Care
Some aircraft — particularly fighters and certain warbirds — exist only as single-seat designs in their operational form. Without a two-seat training version (or a high-fidelity simulator), there is no practical way for an instructor to fly with a student during initial conversion onto the type.
Intuition Check
Do not read this as any airplane or device that simply has two seats. In this context, it means a version intended for training, with room or controls arranged so an instructor and learner can work together.
Example Sentence 1
Because the F-16 is a single-seat fighter, new pilots transition onto the type using two-seat training versions before flying solo.
Example Sentence 2
E-learning scenarios often model procedures from two-seat training versions to show how an instructor would intervene during a student’s first solo practice.