Even before Covid-19 grounded his fleet, Pat Byrne was already scrambling. Having founded CityJet in 1993, the Irish aviation tycoon returned to the business in March 2016 after assembling a consortium of investors to buy back the airline from Germany’s Intro Aviation. Byrne quickly ceased direct scheduled operations, with the airline exclusively operating flights on behalf of other European airlines. The so-called wet lease market is massive in the US but underdeveloped in Europe. Byrne spotted an opportunity and went for it. A merger with Spanish regional airline Air Nostrum was agreed in principle, a move that would have given…