An airline travelled on by thousands of Americans every day exhibits "consistent evidence showing potential lack of airmanship" as well as unsafe and poor piloting skills, according to Federal Aviation Administration (FAA) documents obtained by CNN.
Many travellers would be unaware that they have even flown on Envoy Air. The airline is owned by American Airlines and operates its regional services, using American's name and branding on its aircraft.
It operates 185 aircraft on approximately 1000 daily flights to over 150 destinations in the US, Canada and Mexico.
In one incident in March 2020, an Envoy Air flight was moments away from landing on the wrong runway at an airport in Illinois. With just seconds to spare, the pilots realised their mistake, which if unnoticed could have claimed the lives of dozens of passengers.
The information was included in a letter from an FAA inspector to Envoy Air CEO Pedro Fábregas.
"Collectively, these narratives point to issues that are deeper than what spot training or counselling have been able to resolve," the letter said.
It also detailed one incident where a pilot who had failed their proficiency test was said to have "truly lacked knowledge concerning what is acceptable".
An administrator for the FAA, Steve Dickson, said the report was "based on data that we have been able to glean by working with the operator to identify where there might be areas of emerging risk that they need to focus on".
Envoy Air said in a statement it has been working "transparently and collaboratively to examine the root cause of each potential issue and take any necessary corrective actions if needed".
"Nothing is more important than the safety of our customers and employees," Envoy spokeswoman Minnette Vélez-Conty said in a statement. "If issues are raised - either internally by our team or by the FAA - we work to address them immediately."
The United States Air Line Pilots Association (USALPA) said the US aviation industry has very high standards of safety and these have "proven an effective safeguard to detect any circumstances that could affect safety".
"The airline piloting profession in North America is one of the most highly scrutinised careers, and airline pilots' professionalism has contributed to making air transportation the safest form of transport for passengers and air cargo shippers," USALPA said in a statement.
