One nearly empty passenger jet “climbed like a rocket,” prompting the pilots to exceed their assigned altitude. Others have scraped their tails on takeoff, gone off course, or strayed close enough to other aircraft to prompt mid-air collision alerts.

The common thread: the massive disruptions to the U.S. airline industry caused by the COVID-19 pandemic.

While the plunge in travel has in many ways eased pressure on roads and the aviation system, it has at times had the opposite effect on safety. The rate of highway deaths has risen as motorists speed on empty roads. And the drop in airline passengers has triggered an unusual spate of incidents that are challenging flight safety, according to publicly available reports as well as government, industry, and union officials.

Moreover, the slow rise in air traffic is creating its own demands as parked aircraft are restored to service, and pilots who may have missed training sessions are recalled.

The Commercial Aviation Safety Team, comprised of the U.S. Federal Aviation Administration, unions, and airline officials, last month issued more than 50 warnings to carriers on the unusual factors they need to monitor more closely during the recent industry disruptions, according to documents reviewed by Bloomberg News.

They include tracking safety data related to unusually light aircraft, the stresses from employees fearing they could become infected by COVID-19, and possible fuel contamination on planes that were parked.

“These dynamic changes are creating stress points on our systems and processes,” the group said.

Details of incidents have begun to trickle out through NASA’s Aviation Safety Reporting System, which posts anonymous field reports after validating their authenticity.

They include pilots reporting that unusually light airliners behaved unexpectedly, such as climbing so fast that they exceeded assigned altitudes or couldn't maintain cabin air pressure. Others said the boarding process went so fast they forgot to finish safety paperwork.

Thousands of airliners are parked, some on runways at major airports. Normal flight routines are being disrupted. Training is being postponed. And airline crews face the looming threat of infection and a loss of job security.

“There is certainly a concern that all of these things could be a distraction to crews and could result in an undesirable situation,” said Hassan Shahidi, president of the nonprofit Flight Safety Foundation.

There have been no significant incidents, said Shahidi and others familiar with data collected by airlines.

The FAA said in a statement: “We are closely monitoring the data we receive from voluntary reporting systems and have increased the number of information-sharing meetings we’re holding with operators.”

Indeed, the reason that concerns are being raised at the agency and the safety team is that the industry’s early warning system — which tracks flight data, thousands of reports from individual employees, and internal airline audits — has been adept at spotting issues before they become serious, say FAA and industry officials.

Ali Bahrami, the FAA’s associate administrator for aviation safety, said during a recent online panel that the agency has increased its interactions and oversight of airlines as a result of data it has seen.

Among the incidents raising concern, Bahrami said, were “tail strikes,” in which a jet on takeoff or landing hits its tail on the runway. These impacts, which may be associated with a lighter-than-usual aircraft, can severely damage a plane and lead to costly repairs.

The air-traffic control system has faced similar stresses, said Teri Bristol, the chief of FAA’s Air Traffic Organization, speaking at another webinar. Scores of controllers, who operate in close quarters and can’t work from home, have tested positive for the virus. That has prompted the temporary closing of facilities and the rerouting of flights.

With so many aircraft parked — airlines took more than half of their fleets out of service before beginning to return some planes in recent weeks — the FAA has been paying close attention to safety incidents on the ground, such as the threat of collisions on runways.

“We are seeing surface issues where we just wouldn’t expect to see them,” Bristol said.

NASA’s repository of reports from pilots, air-traffic controllers, and others reflect what Bahrami and Bristol have said. Reports of incidents in March have only just become public:

  • An airline captain landing at Pittsburgh International Airport complained that planes were “parked all over” one of the runways, but it had not been marked as closed with lighted signs.
  • A captain reported that an automated warning system ordered them to “climb” to avoid colliding with another plane. The pilot blamed it on another jet that was climbing faster than usual with a lightly loaded plane.
  • An airline crew said they got a warning that the cabin wasn’t properly pressurized. They had been climbing so quickly with an unusually light load at high altitudes that the plane’s pressurization system couldn’t keep up, they said.
  • Confusion over a missed radio call allowed two planes to fly too close to each other. A controller said that a nearby sector had been shut after another employee tested positive for the virus. “We were working abnormally complex traffic at a very high volume,” the controller said.
  • After aborting a landing due to gusty winds, an airliner at takeoff power climbed so quickly that it exceeded its maximum assigned altitude. “To say I was rattled would be an understatement,” a pilot on the plane said. “I am concerned that we are flying these aircraft too light.”