- Water leaked from plane bathrooms meant Delta pilots lost their autopilot systems, the NTSB found.
- Flooding from two bathrooms caused ice to form around the plane controls, the investigation found.
Water leaking from the bathrooms of a Delta Air Lines plane knocked out its autopilot system and left pilots with limited control of the aircraft, an official investigation into the 2022 incident found.
No one was injured on the flight from Prague, Czech Republic, to New York's John F. Kennedy International Airport on July 7, 2022. But the crew had to declare an emergency and descend to a lower altitude, the National Transportation Safety Board said.
In a report published last week, investigators said that wastewater leaking from the bathrooms that then froze was likely to blame.
Crew members discovered during the flight that there was flooding from bathrooms on the plane, the NTSB said.
The toilet was leaking in one bathroom, and the filter under the sink was leaking in another, the NTSB said. Crew members restricted bathroom use and tried to clean up as much water from the floor as they could, it said.
But the crew then found that the plane's autopilot systems had disconnected, and they were not able to reconnect them, the NTSB said.
Pilots also experienced issues with the plane's roll control, which meant the plane was gradually drifting to the right.
They were unable to fix the drift, the NTSB said.
After talking with dispatch and maintenance control, the pilots were given permission to descend to 9,000 feet, where the ice could melt back into water.
The flight ultimately landed at JFK, after pilots were able to operate the control wheel again at 12,000 feet.
233 people were onboard the Boeing 767-300.
The NTSB said the incident was likely due to human error, with workers not closing the drain mast heater circuit breakers during maintenance before the flight.
The water likely flowed to the plane's controls in the main landing gear wheel well, where it froze, they said.
The plane was taken for repairs after it landed.