Southwest Airlines continues to resort to an "operational emergency" after an unusually high number of aircraft have been taken out of service.
The Dallas-based airline has been forced to cancel hundreds of flights since late last week due to mechanical problems with the fleet. Despite an "all-hands on-deck" staffing policy for its mechanics, the company has failed to solve its problems.
In a statement on Tuesday, Southwest said there was no common theme on the problems facing the 750 planes and it was expanding a staffing protocol introduced last week to "maximize the availability" of the mechanics.
"We require all hands on deck to address maintenance items so that we can immediately return aircraft to service and take care of our customers," it said.
On Tuesday, more than 40 aircraft had maintenance problems – more than twice the average on a typical day. It creates a domino effect that disrupts Southwest aircraft across the country.
According to FlightAware, Southwest Airlines canceled 186 flights on Tuesday – about 4% of its business. Another 730 aircraft was delayed.
The airline's maintenance problems come as the US Federal Aviation Administration examines how the Southwest tracks the weight of checked bags on its flights.
FAA started its probe in February 2018, the FAA told CNN Business on Monday.
The Wall Street Journal, which first reported the story, said the FAA officials and agency documents indicated that the airline's employees made mistakes that led pilots to calculate aircraft failure weights at start.
The errors were described as "systemic and significant", which often results in reported starting weights being 1,000 pounds lower than the actual weight of the aircraft.
Southwest said in a statement to CNN Business that there is a "continuous effort to track and voluntarily report operational data to the FAA so that we can reduce and eliminate any operational risks."
But the airline added that it already has Put into use controls and procedures to deal with haze and balance issues. Southwest said it has shared these measures with the FAA.