Senior pilots at Virgin Australia have alleged fatigue is widespread in their ranks and raised safety concerns about a roster system some claim is working them “to the limits”.

Guardian Australia has obtained correspondence from senior pilots pleading for action to address worker fatigue as Virgin Australia and the Transport Workers Union (TWU) remain in a standoff over a proposal to strip pilots of six days’ annual leave during negotiations for a new enterprise agreement.

The correspondence seen by Guardian Australia reveals:

• The system routinely schedules pilots to work maximum shift lengths – 11-12 hours and longer in the event of delays – on back-to-back days, while allowing for just the legal minimum rest period of 12 hours.

• Pilots have raised concerns with management about the roster software and claim that the private equity owners of the airline, Bain Capital, have not followed through on a promise to replace it.

• Frustration at what they claim is management’s failure to recognise these issues, or respond to staff warning of a resulting “clear, present and increasing safety risk”.

In an internal pilots’ messaging group discussing rostering and fatigue issues, one asked: “Would they like to see blood?”

“The practice of rostering to the limits, ‘because we don’t expect anything to go wrong’, is absolutely crap,” the pilot added.

Responding to questions from Guardian Australia, a Virgin Australia spokesperson said the airline “operates under a robust fatigue management system approved by the Civil Aviation Safety Authority” in “extensive consultation with pilots”, adding that “our pilots have the highest number of rostered days off in the industry at 156 per year”.

Emails between November 2023 and continuing into this year show senior pilots at Virgin Australia drawing a link between the rostering and bidding system, which allows pilots to preference shifts they want to work or swap, and their feelings of fatigue and sense of work-life balance.

The pilots claim the current rostering system, a “lite” version of the software Sabre, is not fit for purpose and that while they accepted its use during the airline’s pandemic-era struggle out of administration, it was now neglecting to bring in a functional system – something workers have called for during enterprise deals dating back to 2007 – to reduce its costs.

The airline posted a $129m net profit last financial year – the airline’s first in 11 years – and the TWU has claimed Bain has failed to address “rock-bottom pay, improve work-life balance and fix unsafe rostering”.

“The rostering / bidding system is intrinsically linked to our well being and our quality of life”, one senior pilot warned in an email in November. “Our lives are dictated by and completely dependent on it.”

In a later email, the pilot wrote: “It is clear there is a distinct lack of, and complete break down of trust in the company from our pilot group, especially in consideration of Virgin failing to meet its [enterprise agreement] obligations … Virgin has proven time again it either refuses to meet them or is incapable of doing so.”

One pilot said “the cancerous lack of morale and resentment will continue to grow unchecked” if pay concerns, conditions and work rules were not addressed.

“Morale is now so low that it’s beginning to have very clear and present safety implications. You can’t afford to pay us more? You can’t afford an accident either,” the pilot wrote, referencing a discussion with staff who conduct safety checks.

Unions split on enterprise agreement

Pilots appeared in dismay after receiving an update from the company in March that a new rostering system project was being paused, according to the correspondence.

The revelations come as the airline pushes a new enterprise agreement that has split the unions representing Virgin pilots.

While pilots represented by the Australian Federation of Air Pilots (AFAP) are understood to be open to a deal that would cut six days of annual days off, pilots represented by the TWU are opposed.

Under the current deal, which lapses at the end of June, pilots are entitled to 12 days off every 28-day roster period, of which there are 13 periods a year. Virgin Australia is proposing that for six of the 13 roster periods, days off would be cut to 11. If no agreement is reached by the end of June, workers will be able to take protected industrial action.

A poll of 180 pilots – of the roughly 1,000 who work at Virgin – conducted by the TWU, revealed 95% of respondents do not feel valued by the airline and Bain, with 93% intending to vote no to the proposed deal and 88% specifically unhappy at the planned reduction in days off.

In the survey, 85% said the rostering system had affected how they managed their fatigue, with 82% saying it had affected their family life and 55% saying it was damaging their mental health.

Should the proposal to cut pilots’ days off go ahead, 42% said they would consider leaving their job.

One pilot told the union that while pilots as a group had raised issues about fatigue, individual pilots were hesitant to alert management when they personally felt fatigued, as it could lead to them being forced to take a medical test. Failing such a test would force off a shift, affecting their pay.

Another pilot told the union that “Virgin is now just a toxic place to work”, while another added: “Poor management, poor rostering, no work-life balance, feeling of being undervalued, feeling of being not appreciated for the sacrifices we make for the company and no support when we need it.”

The TWU national assistant secretary, Emily McMillan, said the revelations should be a wake-up call for Virgin and Bain to take the fatigue and mental health of its pilots seriously.

“Instead, the airline is trying to claw back six days off per year. We need to see this proposal dropped and a fair enterprise agreement settled so pilots can concentrate on the crucial job they do without feeling stressed at work and at home.”

Under the proposed deal – which has been agreed to by the AFAP which represents a majority of pilots at Virgin – pilots would receive a 9.38% pay rise in the first year, and 3% rises in the second and third years, in return for the loss of the six days off.

The Virgin Australia spokesperson said it would soon invite pilots to vote on the new enterprise agreement, which it said “reflects our strong desire to reward and recognise our pilots for the important work that they do, while also protecting our ability to deliver great choice and value to the Australian public”.

“Our pilots also have the highest rest protections in the industry with additional fatigue-related protections included in the proposed EA,” they said.

The spokesperson said the proposed reduction from 156 days off to 150 days would still leave its pilots with more days off than its major Australian competitors. They said the reduction would improve Virgin’s ability to operate during peak flying months.