Two days after being notified by the Vietnamese authorities that 11 survivors had been found and 25 fishermen were missing from the Fung Ching Fuk, Hong Kong officials despatched two Government Flying Service (GFS) aircraft to the area.
The crew of the first search and rescue plane spent just over an hour combing part of the zone in the late afternoon.
The amount of time that could be spent searching the area was limited because the aircraft ran low on fuel. Most of the fuel was used on the two-hour flight to and from the remote islands.
Another GFS aircraft was sent out from Hong Kong the next day and conducted two further searches.
After a 90-minute scan of the zone, the aircraft refuelled in Manila before spending another two hours searching the waters.
A source familiar with the search for the missing crew of the Hong Kong vessel said procedures for refuelling GFS search and rescue aircraft in another country were tied up in red tape. Delays were inevitable because to gain approval, consulates first had to be approached in Hong Kong.