What happened
While supporting a United States Navy training mission, the flight crew elected to terminate their flight early because of icing conditions. During the approach, the crew determined a landing reference speed of 140 knots and a required landing distance of 4,200 feet for a wet runway, utilizing a 20-degree flap setting due to limitations from underwing external storage. The aircraft touched down at the reported 140 knots.
Although the runway length was 8,001 feet, an arresting cable positioned 1,701 feet from the threshold reduced the available landing distance to approximately 6,300 feet. Following touchdown, the pilot-in-command deployed the brakes and spoilers, but the second in command noted that the aircraft failed to decelerate. The pilot reported that the anti-skid system was active and that the aircraft appeared to be hydroplaning. Despite attempts to cycle the brakes, the aircraft continued to accelerate past the runway end, breached an ocean sea wall, and settled in a nose-down position on a sandbar.
Recent weather data indicated significant precipitation prior to the event, with 0.31 inches of rain recorded in the four hours preceding the accident. The aircraft remained submerged in saltwater overnight before recovery, preventing functional testing of the braking system.
Findings
An investigation involving landing performance modeling and ADS-B data analysis concluded that the most probable scenario involved the aircraft touching down at a ground speed significantly higher than the reported 140 knots. The study determined that the aircraft encountered full hydroplaning at speeds exceeding 104 knots. While various factors such as tailwinds or brake failures were modeled, the evidence did not support their presence. The investigation concluded that the combination of excessive touchdown speed and hydroplaning caused by recent heavy rainfall led to the overrun.