DALLAS (AP) — Hundreds of uniformed Southwest Airlines pilots stood in perfect lines in the scorching Texas sun at Dallas Love Field on Tuesday, holding signs that blamed Southwest management for delays and cancellations that have upset passengers.

Every once in a while, a motorist would honk or yell encouragement. Most passengers made a beeline for the security checkpoint inside the terminal.

The protest, which the union said drew up to 1,300 pilots, was the latest example of airline workers trying to put pressure on companies by taking their demands for higher pay directly to the flying public.

Federal law makes it nearly impossible for airline unions to conduct legal strikes. Contract negotiations tend to drag out — often for years. Southwest’s flight attendants have been working under an old contract since 2018.

That slow pace causes unions to look for creative ways to put pressure on management. Sometimes they vote to authorize a strike — Alaska Airlines pilots did that last month — even though there is little chance that they will walk off the job.

Last week, the Air Line Pilots Association, or ALPA, posted an open letter to Delta Air Lines customers, saying its members empathized with travelers whose flights were delayed or canceled, and blaming Delta management. The union said Delta has scheduled more flights than it has pilots to fly, and pilots were working record overtime hours.

Earlier this month, American Airlines pilots picketed near the New York Stock Exchange, and before that, at major airports. Some held signs such as, “Frustrated with AA? So are we.”

Airline unions are hoping to take advantage of strong demand for travel this summer to win increases in wages and benefits.

United Airlines reached agreement with ALPA last month. Terms have not been disclosed, but they likely included higher pay — United’s CEO called it an industry-leading proposal. The deal still needs to be ratified by pilots.

Two regional subsidiaries of American will give pilots a wage premium of 50% through August 2024 in addition to longer-term increase. So-called regional carriers, which operate American Eagle, Delta Connection and United Express flights, are being hit hardest by a shortage of pilots.

On Tuesday at Love Field, which is next to Southwest headquarters, pilots in crisp white short-sleeved shirts with epaulets on their shoulders stood at attention, holding signs that read “Southwest’s operation: From first to worse,” and “Our passengers and pilots deserve better.”

Casey Murray, president of the Southwest Airlines Pilots Association, the union for the airline’s 9,000 pilots, said work has turned into a “flightmare” for pilots because of over-scheduling.

“It’s a struggle every day out there. Our fatigue rates reflect that,” he said. In the first five months of this year, Southwest pilots reported feeling fatigued at more than triple the rate of a year ago, according to figures from the union, which says this raises safety concerns.

Southwest said in a brief statement that it respects the right of employees to express their opinions, “and we do not anticipate any disruption in service as a result of this single demonstration.” The airline declined to comment on the union’s concerns.

Neither the union nor the company would discuss wages or other bargaining topics.

Dallas-based Southwest has been hiring pilots since last year to replace those who took buyouts that the airline offered in 2020, when the pandemic caused air travel to plummet. The union says pilots are not being fairly compensated for handling extra flights, and that Southwest uses outdated crew-scheduling technology that makes it hard for the airline to recover from even minor hiccups.

Southwest, the nation’s fourth-biggest airline, suffered through high cancellation rates last summer and again in early October, when weather-related cancellations in Florida cascaded into a dayslong, nationwide meltdown. It has performed better more recently, including over the Memorial Day weekend.

It is hard if not impossible to know whether picketing at airports helps unions at the bargaining table.

Pilots enjoy particular respect from travelers, and when they picket in full uniform, “they create a powerful image” that travelers remember, said Henry Harteveldt, a travel analyst with Atmosphere Research Group.

Harteveldt said pilots currently have leverage in negotiations because of a pilot shortage and widespread flight delays and cancellations.

“But timing is everything in these negotiations,” he said. “If the economy has a significant slowdown and airlines see business fall off and scale back their flying, then the leverage pilots have today may be gone.”

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