Ace Dallas is an agent with the American Air Intelligence Service.
And that, I fear, is pretty much the sum total of what I know about this fellow. I do not even know what his real first name is, since I am reasonably sure his parents did not choose 'Ace' as their desired name for him when he was a wee little baby.
I cannot even be certain that the "Air Intelligence Service" he works for is America-based. That, too, is conjecture, based on the tales being in an American magazine but since that publication did have a fair number of Canadian-based adventures (Mounties, anyone?), who knows!
My only "proof" that this fellow belongs in this compendium comes from the trove of magazine metadata, philsp.com, which lists these five tales as those of "Ace Dallas, Air Intelligence Service".