The International Air Transport Association (IATA) will hold a meeting with Boeing 737 Max operators, aviation regulators and the US planemaker in five to seven weeks to discuss conditions of the grounded jet's return to service. The airline industry body expects it could take until August before the jet resumes service, but the final decision on the timeline is up to regulators, Alexandre de Juniac, IATA's director-general, told reporters on Wednesday. The summit will aim to "make an assessment on the situation and prepare re-entry conditions in a transparent and collaborative manner, to have alignment with everyone and to do it in the safest way", Mr de Juniac said in a press briefing from South Korea's capital Seoul. Boeing's most profitable aircraft was grounded by global regulators in March after the model was involved in two deadly crashes in Ethiopia and Indonesia in the space of five months. European regulators are evaluating Boeing's proposed changes to the Max and its flight-control system before they agree to lift the ban, while US aviation regulator, the Federal Aviation Authority, said it will not rush into a decision. Mr de Juniac urged aviation regulators to co-ordinate the same timeline across the globe to return the jet into service to avoid disruptions. "We urge regulators to have the most comprehensive, consistent, collaborative approach and the same timeline if possible," he said. "The comprise is to find an appropriate time that's not too short to threaten safety or too long for negative consequences for traffic." The global grounding of the Max is taking a toll on airline operators, according to the association that represents about 290 carriers. "The operational and financial consequences for our members is significant," Mr de Juniac said. "For passengers it has led to some cancellations of flights because of a shortage in jets." IATA does not have a dollar figure yet for the cost to airlines from the cancelled flights and higher costs. Mr de Juniac said the aviation industry needs to restore confidence in both the 737 Max and the process of certifying planes. He called for a single re-certification process that can be implemented globally. The US Federal Aviation Administration met last week with international regulators in Fort Worth, Texas, to discuss the process returning the Max into commercial flights. On the same day, IATA organised a meeting in Montreal with Max operators on the same issue. Mr de Juniac said it was unfortunate that the FAA did not set a timeline for returning the Max into service and hoped regulators could find a "reasonable time-frame" for the jet's safe return to the skies. Boeing has been working on an upgrade to the Max software, which has been identified as a common factor in both plane crashes, but has yet to formally submit the fix to the FAA and has not set a date to do so. Airlines will gather next week in Seoul for the 75th annual general meeting against a backdrop of escalating trade tension between the US and China rising costs as oil prices rebound that are eating into airlines' profits and hurting travel demand.