What happened
The F-28 had undergone deicing twice prior to departing from the gate. However, a duration of 35 minutes passed between the second deicing application and takeoff. During this interval, ice accumulated on the wing surfaces.
During the takeoff roll, the first officer called for rotation speed (Vr) 11 knots early, and the captain rotated the aircraft approximately 5 knots early. Following liftoff, the airplane experienced a stall and came to rest in a bay, where it was partially inverted and submerged.
Findings
The investigation determined that the elapsed time between deicing and takeoff exceeded the safe holdover time for Type I deicing fluid, which is 11 minutes. Additionally, at the time of the accident, the operator did not mandate a specific exterior inspection for ice contamination on F-28 aircraft during periods involving freezing precipitation.
Data regarding accident history indicates that non-slatted, turbojet, transport-category aircraft have been involved in a disproportionate number of takeoff accidents where undetected upper wing ice contamination has been identified as a cause or contributing factor.