In a letter to staff dated April 4, seen by Reuters, Wizz said its Head of Flight Operations Darwin Triggs was stepping down from his role after an investigation into "how the COVID-19 related redundancies were determined and carried out" last year.

The Budapest-based airline announced plans to cut 1,000 jobs, or 20% of its workforce, in April 2020, weeks after a travel shutdown in Europe caused by the COVID-19 pandemic.

In the letter, the airline said an independent review of its handling of the redundancies found no indication it had acted unlawfully but "some factors may have been taken into account that were inconsistent with Wizz Air's culture of open and honest communication and its focus on employee opportunity."

The letter came after an audio recording circulated among pilots purportedly of a virtual meeting in April 2020 at which a Wizz manager told his staff to draw up target lists as the airline pursued 250 redundancies among pilots and trainees.

"We start off with the bad apples, so anyone who has caused you grief on a routine basis," the manager is heard saying in the recording, before suggesting "excessive sickness" or declining to work on days off among reasons for termination.

Asked to comment on the letter and the recording, a Wizz spokesman said in an emailed statement to Reuters: "It's clear that some language was used on an internal call that did not reflect the process being undertaken nor the values of the business and that is a matter of regret."

The spokesman declined to comment on whether it was Triggs' voice on the recording or whether he was still with the company. Reuters was unable to reach Triggs for comment or to determine whether he was speaking in the recording.

Despite intense pressure to slash costs and conserve cash, airlines need to keep enough planes and staff ready for a post-pandemic recovery and future demand growth.

Three months after the purported meeting, Wizz announced a "Cabin Crew to Captain" programme to retrain flight attendants as pilots.

While traditional airlines have received state support throughout the COVID-19 travel crisis, budget carriers' cost-cutting agility has positioned them to gain ground in a recovery likely to be led by short-haul leisure travel.

In the recording, the manager also suggests that pilots employed via a Dutch outsourcing firm should be left largely untouched.

"They're easy to manage because we can let them go at any time. They only have 24 days of (leave) and they're incredibly cheap," the manager says, before concluding: "Sharpen your pencils and let's see what you can come up with."

(Reporting by Laurence Frost; Editing by Nick Tattersall)

By Laurence Frost