American Airlines announced on Sunday that it would extend the grounding of its fleet of Boeing 737 Max jets through Labor Day. The airline had previously grounded the aircraft, used in 115 of its scheduled flights, through August 19. The grounding adds to the considerable cost to Boeing, which is in negotiations about how to compensate the airlines that own its jets. “American Airlines remains confident that impending software updates to the Boeing 737 MAX, along with the new training elements Boeing is developing in co-ordination with our union partners, will lead to re-certification of the aircraft soon,” the airline said in a statement published by Reuters. American Airlines says it needs about 45 days to get the 737 Max back in the air once the Boeing fix is in place.