CHICAGO (Reuters) - The head of the International Air Transport Association (IATA) warned on Tuesday that any discrepancy among global regulators over reapproving Boeing Co's BA.N 737 MAX for commercial flight could set a worrying precedent for future aircraft programs.

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The 737 MAX, Boeing’s newest single-aisle aircraft, was grounded worldwide in March after two deadly crashes in Indonesia and Ethiopia within five months. Boeing is updating flight control software at the center of both crashes that must be approved by regulators before the planes can fly commercially again.

The U.S. Federal Aviation Administration (FAA) has traditionally taken the lead on certifying Boeing aircraft, leaving other regulators globally to follow suit. That process has been supported by IATA, a trade association of the world’s airlines.

But international regulators have indicated they will pursue their own analysis of the 737 MAX and Boeing’s proposed updates, after the FAA suffered a dent to its credibility following 737 MAX crashes.

“With the 737 MAX we are a bit worried ... because we don’t see the normal unanimity among international regulators that should be the case,” Alexandre de Juniac, IATA director general, told reporters ahead of a summit in Chicago.

“We see a discrepancy that’s detrimental to the industry,” he added, urging regulators to make any changes to the single certification process “collectively.”

In an emailed statement, the FAA said it has a “transparent and collaborative relationship” with other civil aviation authorities, but “each government will make its own decision to return the aircraft to service based on a thorough safety assessment.”

In a presentation to the European Parliament transport committee on Tuesday, European Union Aviation Safety Agency (EASA) Executive Director Patrick Ky said the regional regulator has around 20 experts, including test pilots and engineers, examining the 737 MAX design to ensure there were no weaknesses in safety critical areas.

Presentation slides posted on the European Parliament website showed that of the latest solutions presented by Boeing, EASA was satisfied with changes to the flight control computer architecture and believed improved crew procedures and training were a work in progress. However, it noted there was still no appropriate response to issues with the integrity of the angle of attack system.

In both of the 737 MAX crashes, erroneous data to one of the angle of attack sensors led to the activation of an automated system that repeatedly pushed down the plane’s nose.

U.S. airlines are drawing up flight schedules without the 737 MAX into December or early next year, taking a financial hit while the jets remain grounded.

Boeing is targeting regulatory approval for the fixes and new pilot training in October, though the FAA reiterated on Tuesday it does not have a firm timeline to put the jets back in the air.

“Our first priority is safety, and we have set no timeframe for when the work will be completed,” it said.