Originally Posted by
Intruder
Once those guidelines make it into the airline operating manual, though, they become limitations, even if they are the same numbers as Boeing's "guidelines."
The Aircraft Flight Manual (AFM) will contain a figure qualified as a “Maximum Demonstrated Crosswind”, it will appear in the “operational limitations” section only if it is actually considered limiting for either take-of or landing, or for some other reason, such as autoland operation. In the latter case a descriptive clause will accompany the figure. However, the maximum demonstrated crosswind may not appear in the limitations section, leaving one to ponder what is the actual limit?
How this situation arises can be seen by examining the certification process. JAR 25.237 states that – A 90°cross component of wind velocity, demonstrated to be safe for take-off and landing, must be established for dry runways and must be at least 20 knots or a fifth of reference stall speed in the landing configuration (VSR0), whichever is greater, except that it need not exceed 25 knots.
In reality, during the certification test flight process, the manufacturer searches for locations and conditions that not only meet the regulatory requirements but also demonstrate the operational capabilities of their aircraft – that after all is economic sense. A test pilot who flies multiple crosswind approaches, developing technique to near perfection, will obviously be able to handle greater winds than most operational pilots in a variety of situations. Therefore, when a demonstrated crosswind is high, there needs to be some factoring applied to cater for everyday situations. A manufacturer may therefore publish crosswind landing guidelines in various manuals available to the operator.