The story goes that Elvis signed this post card for the on board stewardess Judy Mongello while taking a United Airline commercial flight circa 1962...
The angle, symmetry, and proportions look great. If not real, it's as good as real as my guess is that it having all the bells and whistles, and te alleged provenance, more than 50% of professional authenticators will pass it, issue a COA, and it just might be good at that. With all of Elvis' stylistic variations, and a lot of Presley ink artists hard at work trying to cash in, an in person, or one with an unshakably documented provenance is the only way to tell 100% for sure.