* Bellew to join Ryanair as COO
* To be given responibility for pilot issues
* Malaysia must hire third CEO in three years (Adds quote, details, background)
DUBLIN/SINGAPORE, Oct 17 (Reuters) - Malaysia Airlines CEO Peter Bellew is leaving after just over a year in charge to return to Ryanair as chief operations officer to tackle the pilot shortages that has resulted in it cancelling more than 20,000 flights over the winter season.
The move means that Malaysia will have to appoint a third chief executive in three years as it continues to recover from two tragedies in 2014, when flight MH370 disappeared in what remains a mystery and flight MH17 was shot down over eastern Ukraine.
But for Ryanair Bellew's return on Dec. 1 comes as Europe's busiest airline is trying to recruit additional pilots and persuade existing pilots to stay with the offer of new, improved conditions to avoid a repeat of the cancellations.
Bellew was director of flight operations at Ryanair before he left in 2014. He joined Malaysia as chief operations officer in September 2015 and took over as chief executive in July last year.
Ryanair said that Bellew would be given a specific responsibility for managing pilots. His mission will be "to ensure that the pilot rostering failure which Ryanair suffered in early September will never be repeated," the company said in a statement.
Ryanair in all has announced the cancellation of around 20,000 flights after admitting it did not have enough standby pilots to operate a reliable schedule.
Irish stockbroker Goodbody last week said in a note that Bellew was well regarded in the industry and was "thought to have had a good relationship with the pilots when he was there."
In recent weeks pilots at Ryanair, which does not recognise any labour union, have been getting together on social media to lobby for a major overhaul of the company's employment conditions.
Bellew's decision to leave Malaysia comes just over a year after former chief executive Christoph Mueller left the airline citing personal circumstances a year after being hired on a three-year mission to revive the state-controlled firm.
Mueller later joined Emirates as its chief digital and transformation officer.
Under Bellews leadership, the Malaysian national carrier has been restructuring its fleet.
Malaysia Airlines could not be reached immediately for comment. (Reporting by Conor Humphries; Editing by Louise Heavens, Greg Mahlich)