This discussion jogged a faint memory so I went looking and found this which is an extract from here,
"2004 Flight Operations Symposium Questions May 9 – 12, 2004, Bell Harbor Convention Center"
20. Are the published crosswind guidelines piloted simulations?
<Answer>. The 737 classic, the 757, the 767 and the 777 takeoff crosswind guidelines are based on piloted cab simulations assuming an engine out refused takeoff maneuver at an adverse loading condition using normal piloting techniques. The published crosswinds were selected to provide adequate airplane control. The 737NG and 747 takeoff crosswind guidelines are based on engineering analysis and simulation studies assuming the same
engine out refused takeoff maneuver.
The 737 classic, 737NG, 747-400, 757, 767, and 777 landing crosswind guidelines are based on piloted cab simulations at an adverse loading condition using normal piloting techniques. Both all engines operating and engine out landings were considered. As above, the published crosswinds were selected to provide adequate airplane control.
21. What is the difference between the crosswind guidelines and the demonstrated crosswind data in the airplane flight manual?
<Answer>. The AFM "demonstrated" value is simply the highest crosswind conditions that were encountered during the airplane flight test program.
The recommended crosswind limits were determined by analysis and piloted simulator evaluation, not by flight test.
An interesting comment, the last sentence.
Regards,
BH