He added: "Pilots' rejection of a one-off bonus to work extra hours - a move that management would have liked to pull off in order to lessen the damage being done - has investors anxious that not only may more flights be cancelled, but also that Ryanair is walking into a protracted battle with pilots at the very worst moment".
He told the AGM that the offer applied to pilots at London Stansted, Dublin, Frankfurt and Berlin airports.
Ryanair boss Michael O'Leary has said the firm is planning to make pilots delay a week's holiday as it wrestles with massive flight cancellations.
The announcement comes just hours after a letter was sent to the company by a group of its existing pilots, rejecting an offer of a tax-free £12,000 bonus in exchange for working overtime.
Mr O'Leary explained the current cost of the six weeks of cancellations is £22million.
The Irish Air Line Pilots' Association says the real problem is that Ryanair failed to plan for the implementation of new European safety regulations that take effect January 1 and require all airlines to use a regular calendar year for calculating pilot flight hours and working days.
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SK hynix said, however, Toshiba's talks with multiple bidders have not yet concluded. Things, however, fell through a day before Toshiba made the final decision.
When asked about reports that pilots are threatening industrial action Mr O'Leary responded: "If you want and need to ask your staff to give up holidays no work to rule can alter that". At present there is a risk that Ryanair will be forced to cancel more flights over the coming weeks.
CEO Michael O'Leary says they're entitled to do it as per the pilots' contracts and doesn't believe it will cause problems.
"The bigger issue is that this debacle is opening the floodgates for pilots to demand better pay and working conditions", Heracleous said. One used the word "revolt". But a group of pilots rejected that offer on Thursday and threatened to launch a "work to rule" campaign.
"Airlines are already beginning to see pilot associations flex their muscles with respect to improved compensation packages and this will only grow in the next 12 months as yearly negotiations take place".
Separately, some Ryanair pilots have spoken to the BBC about a "toxic" atmosphere and how they felt "undervalued".
Customers affected by cancellations which run until October 28 will be emailed offers of alternatives or full refunds and details of their compensation entitlement, the budget airline confirmed.