PLANO, Texas (Reuters) - American Airlines Group's AAL.O pilots want compensation for lost pay stemming from flights canceled as a result of the Boeing 737 MAX grounding, the head of the airline's pilot union said on Tuesday.

FILE PHOTO: An aerial photo shows Boeing 737 MAX aircraft at Boeing facilities at the Grant County International Airport in Moses Lake, Washington, September 16, 2019. REUTERS/Lindsey Wasson/File Photo

Boeing Co's BA.N 737 MAX was grounded worldwide in mid-March after two deadly crashes that together killed 346 people in a span of five months and forced MAX carriers like American to cancel more than a hundred daily flights.

“The effect has been real and calculable,” Allied Pilots Association President Captain Eric Ferguson said at a conference for independent pilot unions in Plano, Texas.

Ferguson said APA pilots are seeking a commitment from American similar to one made by Southwest Airlines LUV.N last month when Chief Executive Gary Kelly promised employees to share any reimbursement from Boeing over the MAX grounding.

“We’re looking for the same thing,” said Ferguson, noting that while some 737 MAX pilots have been scheduled on other routes, their overall flying hours have decreased as a result of the cancellations.

Negotiations between Boeing and its customers over the financial impact of the grounding, which has also halted deliveries of more than 250 jets that continue to roll off its Seattle production line, are ongoing.

Southwest is the world’s largest MAX carrier. It has 34 jets parked in the California desert awaiting approval to fly again, and 41 more that were scheduled for delivery this year. American has 24 MAX jets and 16 more due this year.

Ferguson, who became president of APA in July, is working closely with American to ensure that its MAX jets are safely returned to service once the U.S. Federal Aviation Administration approves them.

Boeing is developing a software fix and new pilot training that must be reviewed by the FAA. The manufacturer has repeatedly said it is targeting the fourth quarter for the plane to return to service.

Once the FAA gives 737 MAX approval, American will need around 30 days to prepare the jets and its pilots for commercial flight, APA representatives said.

For Southwest, with over 10,000 737 pilots, it may take between 45 to 60 days following approval before the plane resumes commercial flights, representatives from the Southwest Airlines Pilots Association said at the conference.