While investigators on Friday promised the preliminary inquiry report into the chartered plane crash in Ghatkopar would be released within 15 days, aviation experts are sceptical about it. Reason: reports of the three aviation accidents in Maharashtra in the past 18 months are yet to be released.While a Pawan Hans helicopter with seven people on board crashed off the Mumbai coast on January 13 this year, two people died as the aircraft from the National Flying Training Institute crashed into the Wainganga River of Gondia district on April 26, 2017. On December 11, 2016, a helicopter carrying a couple for a joyride over Mumbai crashed into hills in Aarey Milk Colony in Goregaon, killing the pilot and the couple.On Thursday, the aircraft that took off on a flight test from Juhu aerodrome around 12.20pm crashed in Ghatkopar at 1.11pm, killing four on-board and one pedestrian. A team from Aircraft Accident Investigation Bureau (AAIB), a division of the ministry of civil aviation, visited the site along with representatives of aircraft operator UY Aviation and Indamer Aviation Private Limited, the company repairing the aircraft. Investigators are studying the evidence at the site and the cockpit voice recorder (CVR) to check what led to the crash. According to AAIB officials, the CVR will be taken to Delhi and decoded by Tuesday. “After decoding the CVR, a preliminary report will be prepared in a week,” said the official.“Nothing will come out of the preliminary report as the accident happened on a test flight,” said aviation safety expert Captain Mohan Ranganathan, adding that C-90 aircraft don’t have a digital flight data recorder (DFDR). “The CVR records the conversation in the cockpit. If the crash is a result of a mechanical failure, it can be established only through the voice recording, as no data of the probable mechanical failure may be available.”Former Air Force pilot and aviation expert Vipul Saxena said that Directorate General of Civil Aviation (DGCA)’s record of closing accident reports has been very poor. Damaged parts are mostly sent to the aircraft manufacturer to find the cause. “It’s time for the aviation ministry to get an independent Aircraft Accident Investigation Body like Federal Aviation Administration (FAA, US aviation authority).”Investigations show that after moving north, the plane travelled only up to 57 nautical miles, and then veered towards Juhu at a height of 400 feet. Senior officials from the Airports Authority of India (AAI), which manages the aerodrome, said the plane crashed around four nautical miles away from the landing site (aerodrome), as it could not maintain the height while landing, but denied that it was flying dangerously low. “The approach path for the Mumbai airport begins at a height of 2900ft, which means the pilot starts descending from this height in the direction of the Mumbai runway and turns right to approach the landing at Juhu. A height of 400feet was not a problem as the aircraft had started descent,” said an official.This was the plane’s first flight after repairs.According to earlier reports, the Uttar Pradesh government had bought the 12-seater in 1995 and sold it to a Pune-based company after an accident. They then sold it to UY Aviation. Captain Sai Vinod, director of UY Aviation of Air Safety, was unavailable for a comment.