ATLANTA, GEORGIA — An official investigation into a 2022 incident revealed that water leakage from the lavatories of a Delta Air Lines aircraft led to the failure of its autopilot system, leaving pilots with limited control. 

The flight from Prague to New York's JFK International Airport on July 7, 2022, experienced no injuries, but the crew declared an emergency and descended to a lower altitude, according to the National Transportation Safety Board (NTSB).

The NTSB report published recently suggests that wastewater leakage from the lavs, which subsequently froze, was the probable cause. Crew members discovered flooding from the plane's lavs during the flight, with a leaking toilet in one and a leaking sink filter in another. Despite restricting the use and attempting to clean up the water, the autopilot systems disconnected and couldn't be reconnected.

Pilots also faced difficulties with the aircraft's roll control, causing a gradual drift to the right that couldn't be corrected. After consulting with dispatch and maintenance control, the pilots received permission to descend to 9,000 feet, allowing the ice to melt. The Boeing 767-300, carrying 233 passengers, safely landed at JFK after pilots regained control at 12,000 feet.

The NTSB attributed the incident to human error, as workers had not closed the drain mast heater circuit breakers during pre-flight maintenance. This allowed water to flow to the plane's controls in the main landing gear wheel well, where it froze. Repairs were conducted on the aircraft after landing.