Definition
A landing error in which the airplane, after the round out, remains airborne longer than expected and travels down the runway at low altitude before touching down. It is typically caused by carrying excess airspeed into the round out, which leaves the wing with more lift than needed to settle the airplane onto the runway.
Plain English
The airplane has too much speed as you level off just above the runway, so instead of settling gently onto the wheels it keeps flying along a few feet up. You drift down the runway in this hovering state until the speed bleeds off enough for the airplane to land.
Context Anchor
Encountered during the last part of a landing, just before touchdown, when the pilot is reducing the descent and preparing the airplane to land.
Derivation
Round out (sometimes called the flare) is the part of the landing where the pilot smoothly raises the nose to transition from the descent to a near-level path just above the runway. 'Floating' describes the airplane's tendency to hang in the air rather than settle, because the wing is still producing more lift than the airplane's weight.
Why Pilots Care
Uncorrected floating uses extra runway and can lead to a runway overrun, especially on shorter fields or when landing with a tailwind.
Grounding Statement
If the airplane still has enough speed to keep making lift, it will keep flying even though the runway is right below it.
Intuition Check
Floating does not mean the airplane is drifting sideways or moving randomly. Here, it means the airplane remains airborne too long just above the runway during the round out.
Example Sentence 1
He carried an extra ten knots over the fence and ended up floating during round out, using more than half the runway before the wheels touched.
Example Sentence 2
Excess approach speed caused noticeable floating during round out, requiring the pilot to go around on the short runway.