Southwest Airlines is now lashing out at the union representing its mechanics, suggesting that they may be grounding planes to gain leverage in stalled contract negotiations. This comes on the heels of an FAA investigation into faulty baggage weight estimates at the airline and a financial hit from the government shutdown.

Union talks

On the labor front, Southwest is fighting the Aircraft Mechanics Fraternal Association, which represents nearly 2,400 Southwest mechanics.

Chief Operating Officer Mike Van de Ven said Southwest saw an increase in aircraft being declared out of service on Feb. 12, "just days after our last negotiations session with AMFA." The surge, concentrated at a few bases, occurred even though there were no changes in the maintenance programs, he said.

The airline issued an emergency order last Friday that requires mechanics to get a doctor's note if they call in sick and gives Southwest the power to impose mandatory overtime. Mechanics who don't comply could be fired.

The memo went initially to mechanics in Phoenix, Las Vegas, Houston and Orlando, Florida, and this week to those in Dallas. Still, delays and cancellations have persisted.

@SouthwestAir breaking my heart. First flight cancelled. Second flight we sat on the runway for two hours. Missed connecting flight. Now we can’t get off the plane and have to go to a new gate. They rebooked us, but damn we’re missing everything we had planned today. — Sarah Davis (@smallpanic) February 20, 2019

Southwest canceled about 440 flights — 11 percent of its schedule — by mid-afternoon Wednesday, according to FlightAware. A spokeswoman said the majority were due to bad weather — a storm disrupted air travel in the East — but there were still "a high number" of aircraft sidelined for mechanical issues. Southwest canceled about 200 flights Tuesday, when weather was not a major factor.

Van de Ven said "AMFA has a history of work disruptions" — Southwest has two pending lawsuits against the union — and the airline will investigate the latest incident. He said Southwest was giving as much work as possible to third-party maintenance providers so Southwest mechanics can focus on issues that they have identified.

The union countered that Southwest is "scapegoating" mechanics, and it warned that the conflict "does not bode well" for safety at one of the nation's biggest airlines.

"For Southwest's leadership to connect the airline's self-declared 'operational emergency' to collective bargaining negotiations is simply an attempt to divert attention away from the airline's safety issues," the union said in an unsigned statement.

AMFA accuses Southwest of pressuring mechanics to approve planes for service too quickly because planes that are grounded do not make money for the airline.

"That should be alarming to everybody, including management," Bret Oestreich, the union's national director, told The Associated Press recently.

Southwest and AMFA have been in contract negotiations for more than six years. Mechanics rejected a tentative agreement last fall, and union officials say the two sides remain far apart on pay and Southwest's desire to keep performing some maintenance work in El Salvador. The union says Southwest has fewer mechanics per plane than other airlines, so its workers deserve to be paid more.

While Southwest spars with the mechanics' union, it is also contending with a yearlong investigation by the Federal Aviation Administration into how crews calculate the weight of checked bags and make sure loads are properly balanced in the cargo hold. Southwest said it reported the problem voluntarily and has made improvements.

Financial woes

Separately, Southwest said Wednesday that the partial shutdown of the federal government will cost it $60 million in lost revenue during the first quarter — far more than the airline's previous estimate of a $10 million to $15 million.

Southwest said it has continued to see softer bookings that it blames on the shutdown, which ended officially on Jan. 25. The earlier estimate covered the period through Jan. 23.

Baggage weight investigation

Southwest's troubles with the union is happening at the same time the airline is facing another separate issue — an FAA investigation into how it estimates baggage weight.

Federal officials have told Southwest Airlines to fix the way it calculates the weight of luggage loaded on flights after finding frequent mistakes during a yearlong investigation.

Southwest said Tuesday that it has made improvements in its methods for calculating the weight and balance of loads, and that it isn't facing enforcement action.

The airline said that it voluntarily reported the issue to the Federal Aviation Administration last year.

The FAA investigation was first reported by The Wall Street Journal.

The newspaper said internal FAA documents showed that the airline made frequent mistakes in calculations and luggage-loading practices that could cause errors when pilots compute their plane's takeoff weight.

Maybe @SouthwestAir should just take a cue from other airlines and overweigh everything. My 7.5 lb pooch is 12 lbs according to @americanair scales. Personally, I’m ok with erring on the side of caution. https://t.co/1AmKhmr1Qh — Mary Landesman (@marylande) February 19, 2019

Southwest told The Associated Press that ground workers manually count and record how many bags go on each plane. The airline uses FAA-approved average weights for bags and passengers, then adds the actual weight of fuel and freight to calculate each load. Southwest said it also builds in a safety margin.

The FAA found cases in which the bag load was more than 1,000 pounds heavier than paperwork indicated, the Journal reported.

Safety experts say pilots might respond incorrectly to an engine emergency if they had inaccurate information about the distribution of weight between front and rear cargo bays.

"It can be extremely critical," Doug Moss, a retired United Airlines pilot, told the AP. "If the weight and balance is not calculated correctly, you could have a flight-control issue."

Moss said pilots calculate the thrust and wing-flap settings for takeoff based on weight and other factors, and faulty data could lead pilots to put the thrust settings too low. That could be critical if an engine fails while the plane is still climbing, he said.

An FAA spokesman told the AP that the agency opened an investigation in February 2018. Since then, he said, the FAA directed the airline to develop a comprehensive fix to the methods and processes it uses to determine baggage weight.

Southwest, based in Dallas, asked the agency to close the investigation. The FAA said the agency won't do so until regulators are satisfied that Southwest's corrections are being applied consistently.

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Southwest sought to downplay the investigation, saying that a so-called open letter of investigation is a common way for the FAA to discuss safety issues with an airline.

Since the investigation started, the airline's publicity department said in a statement, "Southwest has implemented controls and enhanced procedures to address our weight and balance program concerns, and we've shared those measures with the FAA."

Those changes include face-to-face verification of loading information between employees, controls on revising calculations before takeoff, new software and more training.

Southwest said it will begin scanning bags on the tarmac this year to improve accuracy. Other large U.S. airlines already use this technology. Southwest's contract with bag handlers did not include a provision for using scanners until 2016. The airline then spent time evaluating technology and testing scanners at a few airports.

Southwest said all the changes it made "have enhanced our weight and balance program and resolved the issues that we originally reported to the FAA."

Southwest, which carries more passengers within the United States than any airline, disputed an estimate cited in the Wall Street Journal article that one-third of its flights took off after faulty calculations of the weight of checked bags, but it declined to give a figure.

No passenger had died in an accident on Southwest until last April when a piece from a broken engine smashed into a window on the plane and a passenger was partially pulled through it. The accident led to stepped-up inspection of fan blades on certain engines used by Southwest and other carriers.

The airline, however, has been fined for safety violations. Notably, Southwest agreed in 2009 to pay $7.5 million to settle FAA allegations that it operated 46 planes without performing required inspections for possible cracks in the planes' aluminum skin.