Aer Lingus chief executive Christoph Mueller was forced to issue an embarrassing apology to staff at the troubled airline last month after they received a memo threatening to impose tough new sanctions on absenteeism.

In the memo dated 21 October, when cabin crew were engaged in a "work-to-rule" protest in a dispute over rosters, staff were informed that abuse of the company's attendance management policy would be considered "gross misconduct" following changes to the policy the previous April.

"Misuse of the policy could lead to non-payment or removal from the sick benefit scheme and/or other staff privileges," it warned. More "tightly specified absence thresholds" of no more than three incidents of absenteeism and no more than 12 days' absence in a rolling 12-month period would also be employed, the memo stated.

The timing of the memo, at the height of the industrial action, could hardly have been worse for management. As a result, in a follow up communication entitled 'An Apology to all Employees of Aer Lingus' issued on the same day, Mueller said that on his return from a business trip to London he had seen the memo with "great disbelief".

"This notice should not have been issued and I immediately directed that it should be removed," he stated. "I have worked extremely hard in the last year to improve the way we communicate with each other at all levels and I am very disappointed the language and tone of this communication piece does not reflect this." Mueller noted that absenteeism is causing a "severe problem" to Aer Lingus, but said that the situation overall had not deteriorated and "we see good progress in most areas".

"I would like to take this opportunity to acknowledge and sincerely thank each and every one of you for your continuing hard work every day," he told staff. "There remain a few areas of concern where absenteeism has actually increased. Therefore it is our intention to step up our management of these exceptions… in order to ensure that we can significantly reduce absenteeism across the entire company."

"These are extremely challenging and uncertain times and we are all having to make sacrifices… I would like to offer my sincere apologies to all of our staff for this communication piece and I can assure you that we will be taking all necessary steps to ascertain how this occurred and to ensure it will not happen again."