Chopper flying critically low led to 2015 Bombay High crash
An inquiry by the Aircraft Accident Investigation Bureau found that the Pawan Hans helicopter was flying at a critically low height, resulting in its crash near Bombay High in 2015. The report further mentioned that the instructor, despite being aware of the low height, didn't take control of the helicopter after the trainee pilot wasn?t able to manage the situation. 
Two years after a helicopter crash near the Bombay High offshore oil field killed two pilots, an inquiry by the Air Accident Investigation Bureau (AAIB) found that the chopper was flying at a critically low height, without the pilots realising it. The Pawan Hans helicopter was on a training sortie on the evening of November 4, 2015. Aviation regulator Director General of Civil Aviation (DGCA) had asked AAIB?to conduct an inquiry. The inquiry report, which was made public on Wednesday, said that the main pilot was flying low and that the other did not realise it. After taking off, the Rontappmeyer (RYTYR) helicopter may have faced difficulties as the moon was waning, the report said. The report mentioned that the instructor, Captain E Samuel, wasn?t disoriented and was aware of the low height of the helicopter. He alerted Captain TK Guha a little late, but even after realising that Guha wasn?t able to manage the situation, Samuel did not take control of the helicopter.AAIB recommended that ONGC, which owns Bombay High along with the helicopter operators, identify helidecks from where night flying can take place. AAIB also said that Pawan Hans pilots need to rest sufficiently before flying. Guha was flying during the night after a gap of almost a year, read the report. READPawan Hans chopper crash: Both pilots on board still missingWatch: Maharashtra CM?s helicopter crash-lands, Devendra Fadnavis safe