If you listen to the audio, it appears he wanted to propose but started to chicken out when his nerves got the best of him. But the crew talked him to going through with it after all. Via AV Geekery:
He proposed to his girlfriend who was flying on an Air Canada flight, seated in 25C to be exact. He did so by speaking to the pilots on the plane to first explain his odd request. After convincing the captain, he was put on the aircraft speakers and beamed his proposal to his fiancé. Fortunately, she said “Yes!” and the plane erupted in cheers.
“Good evening, ladies and gentleman,” he said when the pilot patched him through to the whole plane. “I’m your air traffic controller from the control tower here at the Vancouver airport. I hope all of you have enjoyed your flight this evening with Air Canada from Montreal, and I welcome all of you to Vancouver. The reason I am speaking to you is because there is a very special lady on your flight this evening. Her name is Christine Waters. Christine, can you raise your hand up please. Way up so everyone can see. Christine, I am crazy in love with you, can’t imagine my life without you. You can’t see me right now, but I am down on my knee, I have a ring in my hand. Christine will you make me the happiest man in the world and be my wife?” The whole thing is completely adorable.