waiting to take off] and taxi all the way back to the parking area and meet up with a deicing truck again. That would have put him very, very late, and it may have even caused the cancellation of the flight." The NTSB carried out tests to discover why the first officer was unable to see the ice buildup on the wing of the jet. When the sliding window of the cockpit was fully open, the first officer would have been able to see the outer 80% of the wing, including the black strip used to contrast the white surface of the wing so the flight crew can search for a build up of ice. When the sliding window was shut, as it was in the accident, making out any details of the wing would be difficult, and the black strip would have been distorted by the glass. They also found that the ice light made little difference in how much the first officer would have been able to see. The investigators also requested that Fokker conduct a study of the effects of ice contamination and pilot technique on the F28 aircraft. The NTSB evaluated the data from the tests, and found that the pilot initiated the rotation earlier at instead of the proper rotation speed of . The data from Fokker were correlated with the cockpit voice recording and confirmed that the first officer called a rotation speed of , but the captain did not rotate until 119 knots. Why the rotation was called and initiated earlier than was standard was never established. Deicing procedures at LaGuardia Investigators also focused on deicing practices at LaGuardia. They found that the airport was using only type I deicing fluid, not type II. Type I fluids are used for the actual deicing of the jet, while type II fluids are used for preventing buildup of ice. At the time of the accident, LaGuardia had prohibited the use of type II deicing fluid because tests suggested that if it fell onto runways, it reduced friction. Investigators noted the change had been made because of LaGuardia's shorter runways and because if an aircraft left the vicinity of the runway, it would come to rest in the cold water surrounding Runway 13. The accident report, however, criticized the fact that the majority of the airplane operators in the United States relied only upon type I