New York CNN Business  — 

Almost all employees at United Airlines have complied with the company’s vaccine mandate – and they do not want to fly with unvaccinated co-workers, according to the airline.

United (UAL) is facing a federal lawsuit brought by six of its employees who have applied for a medical or religious exemption to the vaccine mandate. The airline has said that employees with valid requests for exemptions will be placed on either medical or unpaid leave. The employees bringing the suit are challenging the airline’s decision to place them on leave.

US Court Judge Mark Pittman in Fort Worth, Texas, has ordered United to keep employees who have requested an accommodation on the payroll while the case is heard.

But United said in a court filing last week that it’s not practical to allow them to keep working, because some vaccinated pilots won’t fly with unvaccinated staff. In a separate filing, United said flight attendants have stated they would hold similar objections to flying with unvaccinated coworkers.

The company asked for permission to put unvaccinated workers on leave.

“United cannot return the unvaccinated pilots to the cockpit because — aside from the various practical problems with testing and masking — we would face serious and widespread objections from the vaccinated pilots,” said Kirk Limacher, vice president of HR at United, in a court filing. “In fact the objections among our vaccinated pilots are so strongly held that many of them would simply refuse to fly with the accommodated pilots. The distractions and dissension this would cause in the workforce represent an unacceptable safety risk.”

The airline said it is spending about $1.4 million every two weeks to continue to pay pilots who have requested to be exempt from the mandate, even though they are not flying. Last month, United said about 2,000 of its 67,000 US employees, or less than 3%, have applied for a medical or religious exemption. And only a couple hundred workers now face termination for not getting vaccinated or requesting an exemption.

Attorneys for the employees who brought the suit said United’s claim is not backed by any evidence.

“The claim is easily rebutted by showing the instances of vaccinated and unvaccinated pilots flying together throughout the past nine months,” the plaintiffs’ attorneys said in a filing. Even in the last week, the filing states, United had allowed an unvaccinated pilot to fly and there was no issue.

The plaintiffs also dispute that the unvaccinated staff who test negative for Covid-19 would pose a risk to their co-workers.

Vaccinated pilots are “safer flying with an accommodated, unvaccinated pilot who just tested negative for Covid-19 than with an untested, vaccinated pilot,” the plaintiffs’ filing states, because the vaccinated pilot could have a breakthrough case, even without showing symptoms. The plaintiffs’ filing accuses United of attempting to “ostracize those seeking accommodations.”

“Rather than sharing private medical information, United should be informing its pilots — as they do the general public — that the risk of contracting Covid-19 on a United airplane is almost zero.” United executives, and executives at other airlines, have insisted since the start of the pandemic that the exchange of fresh air in cabins during flights make the transmission of Covid-19 less likely than in stores or other places where people congregate.

But United CEO Scott Kirby has argued that it isn’t practical to allow testing instead of vaccines because positive or skipped tests could lead to sudden and unexpected staff shortages and flight cancelations.

Kirby pointed to disruptions experienced by Southwest Airlines which recently canceled 2,000 flights over the course of a weekend because the airline didn’t have enough available employees to fly the planes.

“Imagine if you have thousands of employees on one day calling in and saying, ‘For some reason, my test didn’t pass.’ I mean it is going to be a huge challenge for airlines that are not implementing vaccine requirements,” he said in a call with investors, suggesting that United’s passengers can have more faith that their flights won’t be canceled due to its vaccine mandate.

In the end, Judge Pittman decided to extend his temporary restraining order, meaning United employees who requested accommodations will stay on the payroll while he continues to hear arguments. Pittman has said in earlier rulings that his decision is not based on the merits of the case, but on his desire to maintain the status quo as the case proceeds.