Definition
The highest crosswind velocity, measured at 90 degrees to the runway, in which an aircraft was successfully flown and landed during certification testing by the manufacturer's test pilots. It is published in the Pilot's Operating Handbook (POH) or Airplane Flight Manual (AFM) as a reference value, not as a regulatory or structural limit on the aircraft.
Plain English
The strongest sideways wind that test pilots actually proved the airplane could handle during the testing required to get it approved. It is shown in the airplane's handbook so pilots have a benchmark, but it is not a hard maximum the airplane is forbidden to exceed.
Context Anchor
You will see this when using a crosswind/headwind component chart, checking aircraft performance information, or deciding whether the wind is suitable for takeoff or landing.
Derivation
Demonstrated' is the key word here. It comes from the Latin 'demonstrare,' meaning 'to show.' The value was shown to be achievable during testing — it was not calculated as a structural ceiling. That is why it is a reference number rather than a legal limit.
Why Pilots Care
It sets the published limit beyond which loss of directional control becomes likely during ground operations.
Grounding Statement
If the runway is straight ahead and the wind is partly from the side, this value is about how strong that sideways part of the wind was when the airplane was tested.
Intuition Check
Do not read “maximum” as “the absolute legal limit” in every airplane. Here, “maximum demonstrated” means the highest crosswind that was shown during testing; whether it is a required limit depends on the aircraft’s approved limitations.
Example Sentence 1
The Cessna 172's maximum demonstrated crosswind component is 15 knots, so when the tower reported a 20-knot direct crosswind, the student elected to divert to a runway better aligned with the wind.
Example Sentence 2
With a 14-knot crosswind and a published maximum demonstrated crosswind component of 12 knots, the pilot elected to wait for calmer conditions.