NEW DELHI (Reuters) - Indian rescuers have failed to pick up any emergency transmitter signals from an air force plane that went missing last week with 29 people on board, an official said on Monday, in the latest setback to a search operation in the Bay of Bengal.
Sixteen ships, a submarine and six aircraft have been deployed to search for the Russian-made AN-32 that disappeared on a routine re-supply flight to remote islands in the Bay of Bengal on Friday.
Rajan Bargotra, a senior coastguard official, said the absence of signals from an emergency locator transmitter (ELT ) made the operation very difficult.
"It is important to know why ELT has not worked as it could have helped narrow down the location of the plane," Bargotra told reporters in New Delhi.
The ELT device is meant to start transmitting the plane's location the moment it touches water or in the event of a crash.
There were 21 military personnel on board the plane including six crew. The other people on board were civilians, and some family members of soldiers deployed on the islands.
Scientists at the Indian Space and Research Organisation were using satellites in the search, while the navy scoured an area of about 14,400 square nautical miles.
Difficulties have been compounded by stormy monsoon weather in the Bay of Bengal.
(Reporting by Rupam Jain; Editing by Robert Birsel)