A Transair Beoing 737 cargo jet sits on the tarmac of the Transair Cargo Facility at Dainel K. Inouye International Airport on July 2, 2021 in Honolulu, Hawaii.

Eugene Tanner | AFP | Getty Images

National Transportation Safety Board investigators plan to use sonar imaging on Monday to try to locate a Boeing 737-200 cargo jet that crashed off the coast of Hawaii last week.

Transair flight 810 made an emergency landing in the sea off the coast of Oahu at around 1:30 a.m. local time on Friday. The pilots of the cargo plane reported engine problems shortly after leaving Honolulu. Both pilots were saved.

The NTSB said it must first find the exact location of the 46-year-old aircraft before the cockpit voice and data recorders can be restored.

“Investigators plan to use side-scan sonar on Monday to examine the debris field, the condition of the aircraft and its location, including the depth of the aircraft below the surface,” it said in a statement. “This information is used to determine how and when the recorders can be recovered and how and if the aircraft will be recovered.”

The NTSB said it is also planning interviews with the two pilots, air traffic controllers and maintenance staff at the cargo airline Transair.

The agency said a small amount of floating debris was recovered and examined by NTSB. It can take months to determine the exact cause or causes of the crash.

The carrier did not respond to a request for comment.

One of the pilots told an air traffic controller that the plane had lost one engine and that there was a possibility of losing the other, according to audio posted on LiveATC.net.

The pilot warned them that their altitude was too low, but another pilot replied that they could not climb.

The NTSB said it met with parties to the investigation on Saturday – the Federal Aviation Administration, the National Air Traffic Controllers Association, Boeing, Pratt & Whitney, who manufactured the aircraft’s engines, and Rhodes Aviation – the aircraft’s operator.