It's an oftenly word used in the drawception website, and are the initials of the word "Pass it on"
- "draw your favourite character PIO"
-"something cool PIO"
Used in the game drawception as: pass it on, when you don't want the theme to derail the next person hass to use that exact sentence in the next drawing/explainment.
Favorite spongebob scene, PIO
Favorite song, PIO
Pilot Induced Oscillation. New pilots are often too abrupt on the controls causing an overshoot of the desired altitude or airspeed followed by hasty over correction trying to maintain a desired state. This results in a porpoise like undulation.
Avoid a PIO by applying small control inputs slowly over time. Don't "saw" the controls.