By David Shepardson
WASHINGTON (Reuters) - Southwest Airlines (N:LUV) on Thursday extended its cancellation of 737 MAX flights through early August as the grounding of the Boeing Co (N:BA) jet continued and threatened to impact nearly all of the busy U.S. summer travel season.
Southwest, the largest operator of 737 MAX airplanes worldwide, said it would now keep the aircraft off its flight schedule until Aug. 10, instead of through June 6.
The revision will remove roughly 371 weekday flights from its total peak-day schedule of more than 4,000 daily flights, which is about 10% higher than the 330 weekly flights it said were being cut through June 6.
American Airlines Group Inc (O:AAL) and United Airlines Co (O:UAL) have both canceled flights into June.
Boeing did not immediately comment, but said last Thursday it was standing by its "present mid-2020 estimate for return to service" of the best-selling MAX, which has been grounded worldwide since March after two fatal crashes killed 346 people.
The Federal Aviation Administration declined to comment.
One unresolved issue remains over whether Boeing will need to adopt design changes to address two bundles of wiring that may be too close together, which potentially could lead to a short circuit and a crash if pilots do not respond appropriately.
The issue has been under discussion by the FAA and Boeing for more than a month and it is not clear when it will be resolved.
Last week, Boeing said it was continuing to "perform the appropriate analysis including lab testing, fleet data assessment and third party reviews." It said it was "premature to speculate as to whether this analysis will lead to any design changes."