Choppy waters and high winds are making difficult the ongoing search operation for the Indian Air Force AN-32 transport aircraft that disappeared over the Bay of Bengal on Friday morning. The round-the-clock search, which extended into its third day Sunday, is initially covering an area of 5,000 square kilometers (1,930 square miles).

The plane was flying east from the Tambaram air force base near the southern city of Chennai on the Indian mainland to Port Blair, capital of the state of Andaman and Nicobar Islands, when it experienced rapid loss of height when flying at 23,000 feet and went off radars. It had 29 people on board, of which 21 — including the six crew members — were military personnel and the remaining eight were family members of soldiers posted on the islands.

The last known location of the aircraft was about 150 nautical miles east of Chennai. Based on data provided by the Indian National Centre for Ocean Information Services, the search is currently focused on a triangular area around that spot and could be extended to 9,000 square kilometers if the current search doesn’t find any wreckage.

At least 16 ships, a submarine and six planes, including two P8i aircraft which can search in the dark, have already been deployed in the search. Several other planes, including a Dornier, another AN-32 and two C-130s equipped with infrared sensors, are on standby. The country’s air force, navy and coast guard are all involved in the search.

A spokesman for the Indian Air Force ruled out the possibility of technical snags with the missing aircraft, even though a report in a local newspaper said the plane had suffered three technical problems in July alone.

The Russian-made Antonov AN-32, or AN-32 for short, is a twin-engine turboprop plane used for military transport with a range of about 1,550 miles. India has had three other incidents involving the AN-32 previously. In the first one in 1986 the plane went missing over the Indian Ocean. In the other two, in 1990 and 2009, the aircraft crashed.