American Airlines planes sit on the tarmac at Phoenix Sky Harbor International Airport on Saturday.

At least 70 American Airlines ground crew workers at Phoenix Sky Harbor International Airport have tested positive for COVID-19 as of April 27, including four that required hospitalization, according to union officials.

The numbers are expected to climb as individuals from the 1,000-member “below the wing” crews continue getting tested.

The first case at Sky Harbor was reported to the airline on April 8; within 10 days, that number was up to 20, according to Donald Carbonneau, president of Sky Harbor Lodge 2559, the local chapter of the International Association of Machinists & Aerospace Workers (IAM) union that represents portions of American Airlines’ fleet services employees and other airlines at Sky Harbor.

The total number of confirmed COVID-19 cases at Sky Harbor airport are unknown.

AZCIR (Arizona Center for Investigative Journalism) interviewed nearly a dozen American Airlines employees and union representatives, obtained internal company memos and emails, and reviewed hundreds of posts and comments on a private employee Facebook page detailing concerns among employees about the airline’s response to COVID-19 at Sky Harbor. Employees other than those representing their colleagues in unions declined to be identified because it violated company policy and they feared retribution for discussing company business.

AZCIR also contacted American Airlines managers based at Sky Harbor, but they either declined to comment because they were not authorized to speak on behalf of the corporation or did not return messages left by AZCIR reporters.

The known American Airlines COVID-19 cases in Phoenix are among crews who load and unload passenger luggage and cargo on jetways and at baggage claims. They also include maintenance workers and those responsible for directing aircraft at terminal gates.

The airline workers are part of a limited group that federal and state governments have deemed essential employees, working on-location during a pandemic with a patchwork of guidance from local, state and federal officials.

As the limited supply of personal protective equipment (PPE) hampers critical service staff in sectors from healthcare to first responders, other essential workers are facing similar shortages – and rising infection rates. Questions about whether essential workers can stay safe on the job come amid the federal government’s multi-billion dollar bailout of the airline industry and calls to begin reopening business across the United States. In Arizona, Gov. Doug Ducey has yet to make a decision on whether he’ll lift business restrictions set to expire on April 30.

Arizona AFL-CIO Executive Director Fred Yamashita asked Ducey and the state Legislature to provide PPE and COVID-19 testing for all essential workers in a letter dated April 23.

“We need these tests to be available to our workforce as soon as possible, regardless of symptom status,” Yamashita wrote. “It is critical for Arizona to take the lead on ensuring its residents and essential workers safety.”

The letter also highlighted concerns regarding limited information about confirmed COVID-19 cases among American Airlines staff at Sky Harbor, citing the company’s reluctance to share infection data as “the reason that this workforce’s infection rate has spiked.”

Union officials told AZCIR that American Airlines’ refusal to release data is not unique in the industry. Other airlines, officials claim, have been less transparent.

American Airlines ramp employees and their unions claim the surge in Coronavirus infections at the company’s Sky Harbor ground terminals is the result of a delayed response by the airline to distribute PPE such as personal hand sanitizer and masks. They also cited delays by the company – and staff – to enforce social distancing in break rooms where up to 50 employees waited in between flights.

American Airlines did not fill the hand sanitizer stations in break rooms at its Sky Harbor facilities to “conserve the supply of sanitizer,” posting signs as early as April 4 that employees should instead focus on washing their hands, documents show. Employees also claimed the airline is delaying notifications to staff who may have come into contact with a colleague who tested positive for the virus – in some cases more than a week after potential exposure.

“I wouldn’t be shocked to hear tomorrow, or have a conversation with somebody to hear it’s 75 or 80 [COVID-19 infections] just on how it’s gone over the last couple of days,” said Pat Rezler, an American Airline fleet services employee on leave to represent employees for District Lodge 141, another local chapter of the IAM. “I’m afraid that seeing how it took off the way it did, I am afraid that it may have been a little too little too late.”

Before CDC guidelines changed on April 3 to recommend face masks, unions had to push the airlines to allow workers to use their own masks and gloves, said Gary Peterson, the international vice president of the Transport Workers Union, which also represents American Airlines ramp workers at Sky Harbor.

American Airlines spokesperson Kelsey Gion said the airline received personal hand sanitizer bottles for employees on April 10 and distributed them to Phoenix staff immediately. The airline received masks on April 13 and distributed them to employees the following day.

“The safety of our team members remains our highest priority,” Gion wrote in a statement to AZCIR. “In addition to following all (U.S.) Centers for Disease Control and Prevention guidance, we continue to coordinate closely with public health officials to adopt and explore new expanded health and safety measures at PHX including face masks and temperature tests, as well as other proactive efforts.”

The company is not releasing publicly the number of COVID-19 infections among its employees at Sky Harbor or among its more than 130,000 employees worldwide, Gion said.