To fly by the seat of your pants is to navigate a situation using instinct, improvisation, and physical feel rather than preparation, expertise, or tools. It implies managing without the structures and instruments that normally guide such a task. A new manager flying by the seat of their pants is making decisions without established knowledge or procedures to fall back on.
The phrase emerged from the early days of powered flight. In the 1920s and 1930s, aircraft instruments were rudimentary by modern standards, and many smaller aircraft had minimal cockpit instrumentation. Pilots, especially in poor visibility, had to rely on physical sensation to judge the aircraft's attitude — whether they were climbing, banking, or in a spin. The feel of the seat pressing differently on different parts of their body helped them sense the aircraft's orientation. Flying 'by the seat of the pants' was genuine technique.
The phrase appears in American aviation journalism from the 1930s and became more widespread during World War II when vast numbers of pilots were trained on simplified instruments and forced to rely on feel. By the 1950s the phrase had moved from aviation jargon into general usage, applied to any improvised, instinct-led action.
In aviation, relying on physical sensation rather than instruments is genuinely dangerous — spatial disorientation (where your body deceives you about the aircraft's actual attitude) is a leading cause of pilot error. Modern pilots are trained to trust instruments over instinct. In everyday use, flying by the seat of your pants describes improvisation that may be exciting but carries the same risk of going wrong without feedback systems.
'Wing it' is the closest aviation equivalent — also derived from early flying. 'Making it up as you go along,' 'shooting from the hip,' and 'thinking on your feet' describe the same quality of improvised, unplanned action.