I had a flight yesterday out of YUL that was delayed more than 2 hours, and received an email and SMS from Mastercard Flight Delay Pass advising me of my lounge options.
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In theory, so far so good. But in the end it wasn't very useful. As my flight was domestic, I could not access 2/4 locations which were in the international part of the airport.
I attempted to redeem my voucher at Bistrot Montreal-Trudeau but they claimed that their scanner wasn't working so they weren't able to accept any Priority Pass/Lounge Key vouchers.
I then walked over to Pork & Pickle and found it had already closed for the day.