Not conclusive?
It is high time for *United Airlines* and other carriers to step up to the plate and accept NEXUS cards for their original intended purpose. They have three raised logos on them, not two.
I'm aware of what different places say. I'm also aware of the responses I've gotten from both customs officials (mostly in the Nexus office) and airline personal willing to accept these items only.
Even if we agree that if you need to do more than a machine (i.e. secondary, machine not working, etc.) and the immigration officer is ok with a Nexus card only (and we are certainly not agreeing to that - last time I came to YYZ for example, we arrived late - I think around 12:30am...long story...and with our 2 year-old who can't use the machine, and since the special services line was closed at that point, had to use the regular line - agent insisted on passports - that's just one example from over the years). Even if we accepted that premis, you still have to know that airline personal will accept it.
Maybe unfortunately, but it is what it is, airline employees checking ID may or may not accept Nexus as the ID used to check in/board an aircraft to Canada. A check in kiosk certainly won't. The fact is, the airlines have their own set of proof they want to see which may or may not match what CBSA/CBP uses. So it's their right to deny boarding if you don't show a passport. Maybe you will get on. Maybe you will after initial denial, and a fight (doubtful). Or maybe you'll just be denied boarding. You can certainly fight on principal, report to the DOT, etc., as long as that takes, but meanwhile, if the goal is to be on that scheduled flight, any option besides having a passport with you will not make that guarantee, IMO and IME,
If it was a pain to carry your passport, then sure, it might be worth the argument at the airport. But a passport book is not a pain to bring or handle - simply tuck away in a pocket, purse or bag and bring out if you need it and the Nexus card doesn't work. I have tried enough in the past, and when they didn't accept it, just handed over my passport - but in the end, realized its easier to skip the first part and hand over my passport. Incidentally, this works every time on the first try, no argument needed, and I get to the lounge faster.
What others want to do, of course, is up to them - I'm just stating my point of view. But we can be pretty confident that Nexus isn't so well known outside of Canada, so that it just isn't that easy to use for that purpose.
<rant over>