Don't agree with the grounding by the US but understand the rational.
The black box will tell the story.
Regarding training
Flight 235 was the second fatal accident involving a TransAsia Airways ATR aircraft within seven months: Flight 222 had crashed on 23 July 2014, killing 48 of the 58 on board.
Shortly after take-off, a fault in the auto-feather unit of the number 2 engine caused the automatic take-off power control system to auto-feather that engine.[4][a] The flight crew misdiagnosed the problem, and shut down the still-functioning number 1 engine.[4] The aircraft reached an altitude of 1,630 feet (500 m) and then began descending until it crashed.[6][7] The last pilot communication to air traffic control was: "Mayday, mayday, engine flameout."[8][9] At 10:55,[10] the aircraft crashed into the Keelung River, on the border of Nangang District of Taipei and Xizhi District of New Taipei.
It was later found that the pilot did the right procedure but to the wrong engine.
The ASC issued an interim report on 2 July. Without assigning responsibility for the crash, the report confirmed that a still-functional engine number one was incorrectly shut down by the pilot following the failure of engine number two.[1][2] The report also stated that the pilot in command had failed to pass a simulator test in May 2014,
The loss of power from both engines was not detected and corrected by the crew in time and the aircraft stalled during the attempted restart at an altitude from which they could not recover. Ineffective flight crew coordination, communication, and threat and error management compromised the safety of the flight. The crew failed to obtain relevant data from each other regarding the status of both engines. The pilot flying did not appropriately respond to input from the pilot monitoring
https://en.wikipedia.org/wiki/TransAsia ... Flight_235