The investigation noted a number of other factors and suggested changes. They reconfirmed that the pilots should have followed existing procedures and aborted the takeoff when they found that their airspeed indicators were already in significant disagreement as the plane accelerated down the runway. Results from a number of simulations with experienced pilots found that the combination of the overspeed warning horn and underspeed stick shaker while in flight was an overly confusing contradictory set of messages for many pilots; the FAA issued a directive that pilot training would now include a blocked pitot tube scenario. The FAA research had also revealed that the situation also led to multiple other contradictory warning sounds and warning lights that increased the demands on the pilot to fly the plane. The FAA asked Boeing to change some of those warnings, as well as add a new warning to tell both pilots that their instruments disagree, add the ability for the pilots to silence troublesome alarms, and to modify the system so that the pilots can choose which pitot tube the autopilot uses for airspeed readings.