A US regional airline almost didn't have enough pilots to fly its planes because so many wanted to get vaccinated and travel demand has surged

• Piedmont Airlines pilots were "discouraged" from getting the COVID-19 vaccine over the weekend.
• So many pilots wanted the vaccine that the airline wouldn't have had enough to cover flights.
• Pilots receiving the vaccine cannot fly for 48 hours after the injection per Federal Aviation Administration rules.

A vaccination drive for aviation workers at Charlotte-Douglas International Airport created a major staffing issue for a major regional airline over the weekend.

Piedmont Airlines pilots were so eager to get the COVID-19 vaccine that the airline "discouraged" workers from receiving it because it wouldn't have had enough pilots to cover scheduled flights, according to CBS News. The pop-up vaccination clinic was held for airport and airline workers and would've given the pilots easy access to the in-demand inoculation.

But the airline said it wouldn't have had enough pilots available to operate its scheduled flights if too many were getting the vaccine because of "high demand" for travel during the weekend of the vaccination drive, according to an internal memo viewed by CBS News.

Piedmont told Insider that a number of pilots were given the authorization to take time off but not all requests could be accommodated.

"Due to FAA requirements of our pilots to remain out of work post-vaccine we are doing our best to offer flexibility while serving the needs of our customers," Piedmont Airlines spokesperson Crystal Byrd told Insider.

The Federal Aviation Administration currently allows airline pilots to receive the three vaccines under emergency approval from the Food and Drug Administration, including those from Pfizer-BioNTech, Moderna, and Johnson & Johnson. But pilots must wait 48 hours from the time they're injected to get back into the cockpit, posing an issue for airlines without a large number of backup pilots.

Side effects from the vaccine can mirror those from the COVID-19 virus itself and include muscle pain, headaches, and fatigue, which could hinder a pilot's ability to safely operate an aircraft. The same 48-hour interval must be observed after the second-dose as well, which is when side effects may be worsened since the body has built up some protection from the first dose.

Piedmont is a subsidiary of American Airlines and operates a fleet of more than 50 Embraer ERJ145 regional aircraft, according to Cirium data, from East Coast bases in Philadelphia and Charlotte. American relies on Piedmont to service feeder flights between its hubs and smaller cities in its network.

Daily passenger numbers in the US have been consistently rising since mid-February, according to Transportation Security Administration data, with new pandemic records being set in March. Travelers are returning to the skies in earnest on the heels of an accelerated vaccine rollout and another round of stimulus checks from the federal government.

Read more: Airline workers have lower rates of COVID-19 than the general population - and airline CEOs say it's proof that flying is safe

"Piedmont is strongly encouraging all of our team members to get vaccinated and offering an incentive to do so," Byrd said.