New Delhi, August 1

The missing AN-32 aircraft, which had flown multiple times over the Bay of Bengal carrying military personnel and equipment, did not have an underwater locator system, making it difficult for the rescuers to pinpoint the position of the plane that went down over the sea with 29 persons on board on July 22. In fact, none of the upgraded AN32 aircraft, the main workhorse of the military, has an underwater locator, unlike the modern transport planes such as C130J or C17.This means the search and rescue team has no idea where the plane is. The search, which entered the 11th day today, is being carried taking into account the last contact point of the aircraft before it disappeared. “We are using sonars of submarine, ships and other naval assets to locate the aircraft. There is no signal available to track the missing aircraft,” a defence source said, adding the search would continue.The missing aircraft came with two Emergency Locator Transmitter (ELT)—a stationary ARTEX C406-1 ELT manufactured by ACR Electronics/Artex Products, the US, and a French-made portable KANNAD 406AS ELT manufactured by Orolia. In emergency, the pilot has to activate the ELT beacon manually. The integrated ELT gets activated when the impact is about 2.3 G or 4.5 feet per second.However, ELT would not get activated automatically since radio waves are not transmitted in water. “There is no signal from ELT under water for this reason,” IAF sources said.Trials were already on to procure underwater ELTs for the aircraft and, as an emergency measure, effort is to have some kind of an underwater ELT on any aircraft that flies over water.Also, the AN-32 aircraft does not have the Automatic Dependent Surveillance – Broadcast. This system relies on navigational satellites to automatically transmit an aircraft’s journey in real time and it can be switched on and off based on operational needs.Defence Minister Manohar Parrikar had said as per the standard operating procedures started at 1230 hours, one hour after the scheduled arrival at Port Blair and nearly three-and-a-half hours after the plane went out of ground radar cover area. It was only at 1225 hours that Maritime Rescue and Coordination Centre, Chennai, reported that an IAF AN-32 (AF-330) was not in contact. The weather at the time when the plane went missing was overcast with multi-layered clouds and embedded convection. — PTI