Source: Aeroinside.com
An Expressjet Embraer ERJ-145 on behalf of United, registration N15574 performing flight EV-3968/UA-3968 from Chicago O’Hare,IL (USA) to Montreal,QC (Canada) with 50 passengers and 3 crew, was enroute at FL350 about 50nm northwest of Buffalo,NY (USA) when the crew reported smoke in the cockpit and diverted the aircraft to Buffalo for a safe landing on runway 23 about 25 minutes after leaving FL350. Emergency services checked the aircraft, the aircraft subsequently taxied to the apron.

A replacement Embraer ERJ-145 registration N14148 reached Montreal with a delay of 6:40 hours.

The occurrence aircraft remained on the ground for 14 hours then positioned back to Chicago.