As the search for the missing AN-32 continued for the 11th day on Monday, the absence of an underwater locator beacon in the missing aircraft is proving an obstruction for search operations.

India is not only using its own satellites, but has also contacted the US for any information their satellites may have captured on the missing plane.

According to available information, none of the upgraded AN-32s have underwater locators. The aircraft had two Emergency Locator Transmitters (ELT), one at the tailfin, and another in the cockpit.

Defence Minister Manohar Parrikar said in the Rajya Sabha that the ELT would get activated only if the aircraft hit water with a force of 20 G. The ELT, however, depends on a battery, the life of which is around 72 hours.

According to sources, the AN-32, however, did not have a Underwater Transmitter Locator Beacon. This locator gets activated when it comes in contact with water and emits signals for around a month. Sources also said that the Indian Air Force was in process of procuring underwater locators.

The AN-32, with 29 people on board, went missing on July 22 when it was on a routine sortie from Chennai to Port Blair.