A medical aircraft carrying six people is missing off the Massachusetts coast after air traffic controllers lost radio contact. Tracking data showed the plane had fallen sharply in altitude shortly before communications ended.

The flight was described as a medical transport, a category of operation used to move patients and clinical staff between facilities. Public accounts have not identified those on board, the operator, or the aircraft’s intended destination.

Tracking data showed the plane had fallen sharply in altitude shortly before communications ended.

A steep loss of altitude followed by silence on the radio is treated as an emergency in civil aviation, especially over water, where low-altitude radar coverage can be thin. Investigators typically review the last known position, weather, and recorded flight path when an aircraft disappears under those conditions.

Coastal airspace off Massachusetts is used by airliners, private pilots, and specialized medical operators. Locating a missing plane over the ocean can take hours or longer, depending on sea conditions, visibility, and how precise the final coordinates are.