On Monday June 8, at exactly 9:23 PM, a Dornier aircraft belonging to the Indian Coast Guard suddenly dropped off the radar and crashed into the sea off the coast of Chidambaram in Tami Nadu. The aircraft was commissioned just about a year ago, and was carrying three men on a routine surveillance sortie. A week later, the Coast Guard has still not been able to find the debris, or the whereabouts of the three men - pilot Deputy Commandant Vidyasagar, navigator Deputy Commandant MK Soni and co-pilot Deputy Commandant Subash Suresh.The search operations are being spearheaded by the Easter Region HQ of the Coast Guard, commanded by Inspector General SP Sharma.The last known position of the aircraft was 16 nautical miles off the Chidambaram coast, at an altitude of 9000 feet. So far, at least 12 ships from the Navy and Coast guard, one submarine, two aircrafts and several helicopters have been delegated to search for the missing aircraft and the men. On June 15, an unmanned under-sea vessel, Sagar Nidhi, belonging to the National Institute of Ocean Technology was brought in to gather more information about the seabed and the location of the aircraft. The NIOT probe vessel has the capability to profile the seabed. A ship belonging to Reliance Industries Limited in Kakinada, which has the capability to lift the aircraft from sea, has been kept on standby.In spite of this, families of the officers and common citizens have aired their concerns on the delay in finding the aircraft, and have also openly showed their impatience. So what's taking so much time?There are several challenges which the Coast Guard is facing.The aircraft plunged 5000ft in a little more than just two minutes, going off the radar all of a sudden. After it started losing altitude, it swerved west, then south and then east before vanishing. There were no mayday calls, emergency alerts or SOS signals from the flight. There were no clues.Most importantly, the Emergency Locator Beacon, or the ELB, of the aircraft did not get activated and did not send any distress signal.This made it difficult for the CG to localize the aircraft. They were working on just one fact: its last know position at an altitude of 9000 feet. They had to make several assumptions to try and locate the aircraft. There was no sign of debris either. So the process of localization took time. Even as search operations began, the CG was waiting for the radar data from Trichy, Meenambakam and Porur. This process at least took them 24 hours, even as a long range maritime surveillance aircraft from INS Rajali was called in early morning on June 9th. Since the ELB did not work, the Coast Guard had to bring in a ship with SONAR capabilities from the Navy. The nearest ship was 400 miles away from the probable site of the crash, at Vishakapatnam, and it could arrive only 36 hours after the incident. The submarine which is conducting the search now too was called in from Vishakapatnam.Further, the depth of the ocean in these parts ranges from 800mts to 1000mts from surface level, making it even more difficult for search operations.Experts say that such sea-based search operations with few clues available can be very difficult. “It is quite literally searching for a needle in a haystack,” says Commodore Shekhar, a retired Naval officer who was a submariner.Officers in the Coast Guard say that the NIOT probe is expected to pin-point the location of aircraft, and that will enable them to operate the equipment of the RIL vessel to locate the aircraft to bring it to the surface and salvage the aircraft. The submarine has picked up signals from the aircraft at least 20 times. This has enabled the search operations to be focused on a localized area of around 1.5 miles around the last known location of the aircraft. Sources in the Coast guard are confident of finding the missing aircraft soon.So what could have happened to the aircraft, how did it crash?Experts say that it is too early to know for sure. “We cannot say anything about this particular case. In general I can say that there are only two broad possibilities – either there was material failure or a human error. This could happen if over a period of time as complacency sets in over training and maintenance,” says Commodore Shekar, “but in this case, it was a relatively new aircraft and between the three they had about 2000 hours of flying.”