New Delhi, Jul 14 (PTI) It was human error that led to the fuel switches being cut off before Air India's Boeing 787-8 plane crashed in Ahmedabad last month, and there also should have been more transparency in the AAIB's preliminary report on the accident, aviation expert Captain Mohan Ranganathan said on Monday.

His comments come at a time when the pilots' associations have flagged concerns about speculations of possible pilot error for the AI 171 flight crash that killed 260 people on June 12. On Sunday, the Indian Commercial Pilots' Association (ICPA) said the crew of the flight acted in line with their training and responsibilities under challenging conditions, and the pilots should not be vilified based on conjecture.

Citing the Aircraft Accident Investigation Bureau's (AAIB) preliminary report, Ranganathan, also a former airline instructor pilot, said the first fuel switch failed, and one second later, the second fuel switch failed before the plane crashed.

"The switches do not move back because of an electric power failure. The switch does not slide back and one has to pull it out of the slot, then move it to run or cutoff position...it is not something which automatically happens, it must be manually done," he said.

"It is a human error," Ranganathan claimed.

AAIB, in its preliminary report on the Boeing 787-8 crash released on Saturday, said the fuel supply to both engines of the plane was cut off within a gap of one second, causing confusion in the cockpit soon after takeoff.

"In the cockpit voice recording, one of the pilots is heard asking the other why did he cut off. The other pilot responded that he did not do so," the report said.

On whether it is not too premature to make a conclusion, Ranganathan noted that AAIB did not give basic data from the cockpit voice recorder and when someone says "it is too premature, you know that the engine fuel switches do not move automatically. They have to be selected manually.

On the possibility of mechanical or software issues in the aircraft, Ranganathan said representatives of US NTSB (National Transportation Safety Board), Boeing, GE and others were involved in the investigation. If there were mechanical issues or a software issue, an emergency alert would have been issued, and nothing has come up; it is very clear that there is no mechanical or software issue.

While mentioning that there should have been more transparency in the report, he claimed that the AAIB has left it open for different kinds of interpretations.

"We don't even know what is the rest of the conversation in the cockpit when the engines failed, when the fuel switch (was cut off)..., the crucial part of take off, engine failure, what action they (pilots) took, what were the conversations and alarms, these are very important (but) that is not there at all," Ranganathan said.

ICPA, which represents narrow-body pilots of Air India, on Sunday said it was deeply disturbed by speculative narratives emerging in sections of the media and public discourse, particularly the reckless and unfounded insinuation of pilot suicide.

"There is absolutely no basis for such a claim at this stage, and invoking such a serious allegation based on incomplete or preliminary information is not only irresponsible -- it is deeply insensitive to the individuals and families involved," it had said in a statement.

Civil Aviation Minister K Rammohan Naidu, on Saturday, said one should not jump to any conclusions on the role of pilots in the Air India plane crash, and there are multiple things that need to be looked into before preparing the final investigation report.