Originally Posted by
bocastephen
I believe there was a thread or post some time ago where the UA contractor agents in YYZ refused to accept Nexus for check-in and caused a big kerfuffle, so it's not a new problem.
Its been going on for ages and not just UA. AC is
usually good with this now, but not always. US airlines in general don't accept it (and I don't believe PD does for transborder flights, either). UA check-in agents at YYZ, including prior to their outsourcing, so the actual UA-employed ones didn't accept them, either (and I flew out of there monthly for a long time and knew a lot of them by name). It's just much easier to use a passport for ID for the airline, and I wouldn't assume they would let you fly, depending on agent, with just a Nexus card.
Its also important to note, that while Canada may accept Nexus as valid for entry or as proper ID to board a flight into the country, airlines can still have their own requirements different than the ones that Canada (or the US, though in this case, its definitely Canada) requires. Also, at least for a while, and not sure if its different now now, Canada allowed the use of a Nexus card for entry only at the automated Nexus machines, meaning that if the machines weren't working and had to see an agent, or one got sent to secondary, technically, a Nexus card on its own may not be enough. This is another reason why the airlines may be more strict.