TN and foreign travel

I travel internationally (Europe, South America) as part of my employment for the US company that is named on my TN visa. I have received mixed messages re: surrendering the TN visa when I leave by air from the US for these trips. When I returned from one trip, an officer told me I should have surrendered it when I left. Other times, they've said nothing. I recently had to surrender it to an airline check-in agent who wouldn't let me travel without surrendering it. On my return, I immediately had the TN re-issued (they just reprinted the paper visa), but the officer said I should not have surrendered it. It's a multiple entry visa and should not be surrendered. What's the real story?!

Yes, you should not surrender it.
I was told not to.
The airline agent know nothing at all about immigration status.
They are just doing what ever they were instructed to.
aka. Get traveller's I94 if they weren't US citizen or GC holder.
They have no single clue about TN and other special circumstances.
What I do when I board an international (Outboud of North America) is to tear and hide the TN out b4 approaching check in counter. THey will ask for I94 usually when you got your boarding pass.
When they ask for one say, you don't have one or you left it at home. They will give you BS, but god knows you are more knowledgable in this matter. If they really threat you out and insist not to let you go(really rare), ask for their supervisor.

I had done this several times.
They always give me BS. I just ignore them and forgive their ignorant. Don't even bother to waste time to argue.

Multiple entry visas are not supposed to surrender your I-94 when you leave the US unless your visa is expired. An airline agent really should know that. Just point it out that it is a multiple entry visa, and that should do it. For extra back-up, print off a page from the USCIS or Department of state website that says TN is a multiple entry visa.

Because it is TN visa an airline agent from a country other than Canada or Mexico may not be knowledgable about it. They don't have 'em.

I've had similar problems with homeland security when returning to the US by air from outside north america. On my last flight, the verbal feedback from the US officer was that the TN visa should be revoked upon re-entry to the US when the person has visited a country outside the western hemisphere. I don't know where he got this policy from, or where to find written verification. They ended up letting keep it, but I may not be so lucky next time.

Airlines have no business touching your TN-visa. Whenever I check-in I make it clear if they start fondling my visa that if they touch it I will make it painful for them.

When they ask for one say, you don't have one or you left it at home. They will give you BS, but god knows you are more knowledgable in this matter. If they really threat you out and insist not to let you go(really rare), ask for their supervisor.

Canadians don't actually need an I-94 if they enter in B-1/2 status (usually), so if you pull out a Canadian passport and tell them you never got an I-94 then they should be okay with that. The fact you have a multiple entry I-94 shouldn't come up.

The thing I find interesting about this is that I have had the same problem, but when you cross a land border it is the other way around because CBSA collect them. And they never take them off you unless you ask them.