Definition
An unequal amount of lift produced by the two wings of an airplane at the same moment, causing one wing to rise while the other stays down or drops. In a crosswind landing, a lift differential occurs when the upwind wing generates more lift than the downwind wing, tending to roll the airplane away from the wind.
Plain English
One wing is making more lift than the other, so the airplane wants to roll toward the side making less lift. It is the difference in lift between the two wings, not the total lift.
Context Anchor
Seen in landing discussions, especially during crosswind landings or any touchdown where one wing rises after the wheels contact the runway.
Derivation
Differential' comes from the Latin 'differentia,' meaning a difference between things. In aviation it is used whenever two related values are unequal — here, the lift on the left wing versus the right wing.
Why Pilots Care
An uncorrected lift differential after touchdown can cause a wing to rise, leading to loss of directional control or a ground loop.
Grounding Statement
Picture the airplane rolling along the runway while one wing is still being lifted more strongly than the other; that lifted side wants to rise.
Intuition Check
Do not read “lift differential” as simply “the airplane has lift.” The key idea is uneven lift: one side is producing more lift than the other.
Example Sentence 1
As the crosswind gust hit during rollout, a lift differential developed and the upwind wing began to rise, so the pilot added aileron into the wind to level the airplane.
Example Sentence 2
The pilot held aileron into the wind to prevent a lift differential from raising the wing during rollout.