The Titanic disaster lay all of a decade off the last time Hibernian won the Scottish Cup.
Hibs were easily the more carefree of the two sides in the opening exchanges and their initiative paid off within two minutes as Pa Kujabi deftly picked O'Connor out and the veteran striker's clever flick sent the Easter Road faithful into raptures.
But far from building on their momentum, Hibs retreated into a fragile shell, too unsure of their defensive capability to look anything but nervy, while their midfielders lacked presence.
Aberdeen came back strongly after half-time and Rory Fallon's leveller scored high on artistic merit.
He snapped on to Matt Doherty's attempted clearance and took the full back's dropping header on this chest before delivering a volleyed lob which left Graham Stack clutching air as the ball soared over his head from 22 yards.
Aberdeen prospered for a spell and Fyvie came close with a curving attempt. But the coup de grace for Hibs came from the lively Leigh Griffiths from a counter-attack.
O'Connor dropped back from an offside position to switch a pass ahead of his team-mate, who got goal-side of Clark Robertson and measured his shot precisely across Brown.
"I do know we'll have to play a lot better than we did today," the former Bohemians boss said of the final.
"All our players will be desperate to play in the final. I know all about the Cup jinx -- they were telling me about it as soon as I got in the door at Easter Road. For the moment, I'm off back to Dublin and I would imagine I'll have a glass of stout or two tonight."