MONTREAL—A plane that went down on an island near Old Montreal on Saturday night was carrying a marriage proposal banner at the time of the deadly crash, authorities said Sunday. A spokesman for Canada’s Transportation Safety Board said the aircraft was towing a banner that read “will you marry me” when it crashed, killing a passenger. The pilot remained in hospital as of Sunday night. “We are looking to speak to the pilot when possible,” Chris Krepski told The Canadian Press. Montreal police said they answered a call reporting a crash that happened at roughly 6 p.m. at Park Dieppe near the Concorde Bridge of Montreal’s Ile Sainte-Hélène, not far from where a music festival was taking place. Police did not share details about the victims except to say that they are believed to have been the plane’s only two occupants. Krepski said in an interview that officials received reports …