Passengers on cancelled flights have complained that notice was far to short and that it was hard to claim compensation.
"This is another blow for the thousands of passengers who have already had to endure huge inconvenience as a result of this fiasco".
Until now, they say, they've been scattered and isolated, making them much less powerful.
Mr O'Leary said the airline had "some goodies" to propose to pilots, but added: "If pilots misbehave, that will be the end of the goodies".
The association also says Ryanair is struggling to cope with a high turnover rate among pilots as the airline expands its fleet.
"I don't even know how there would be industrial action in Ryanair", he said. "It should be serving it up in black and white". Up to 400,000 people booked on the 2,000 scrapped flights risk missing business trips and holidays.
There have been suggestions of a strike over conditions at Ryanair, an airline where CEO Michael O'Leary had previously referred to pilots as "glorified taxi-drivers".
The Ryanair low-priced carrier promises to solve the problem of over 95% of the affected passengers from the cancelled 2100 flights of the airline until the end of the week, reports Mediapool.
On Thursday, Sky News reported that Ryanair now plans to hire 125 new pilots "within the next week or two". Headlines about stranded passengers could damage British politicians, he claims.
Because of the multiple flight cancellations, Britons have been left in foreign countries, with some unable to get a new flight for days. Others said they would not book a Ryanair flight while services were threatened with cancellation.
Balpa general secretary Brian Strutton said: "It seems Ryanair has been just about scraping through the summer schedule and having no flexibility in the system, coupled with a miscalculation of pilot annual leave, has led to this disastrous situation".
However, he also used the meeting to outline a stick-and-carrot approach to dealing with pilots after some prepared a letter demanding new contracts.