In older commercial airplanes, the design of the control panel allows any changes in flight controls made by one member of the flight crew to be immediately viewed by the other crew members  In recently manufactured aircraft, however, a crew member' s flight control changes are harder to observe, thereby eliminating a routine means for performing valuable cross-checks
As a result, the flight crews operating recently manufactured airplanes must inform each other verbally about flight control changes much more frequently
How frequently an airplane's flight crew members will inform each other verbally about flight control changes depends in large part on how long it takes to perform those changes.