Classified is run by OTG, a company that designs, builds and operates restaurants and stores in airport terminals and is United’s partner in a $120 million overhaul of Terminal C; by the end of the year, OTG expects to have opened 55 restaurants and stores in the terminal, according to Eric Brinker, the company’s vice president for experience.

Since I didn’t have a plane ticket, Mr. Brinker had to escort me to Classified and stay near me throughout because according to Transportation Security Administration rules, the escort and the escorted always have to be within earshot and visibility of each other. My other companion was my father, Vikesh, who has 1K status with United, meaning he flies at least 100,000 miles a year with the airline; in fact, he was among the group that actually received a Classified invite.

United is staying mum on which fliers get asked to dine. Maggie Schmerin, a spokeswoman for the airline, said, “It is invitation only, exclusively for United customers.” While my dad got the ask, other United frequent fliers reportedly did not, including Zach Honig, the editor in chief of the online travel site the Points Guy.

I may not be able to shed light on how invitees are determined, but I can divulge Classified’s “secret” location: the restaurant is tucked down a hallway behind the French bistro Saison. Fliers with a reservation are met at Saison’s entrance by an OTG employee and escorted to the sleek and airy room, which overlooks United planes waiting at the gates and has dark oak floors, navy leather banquettes and clusters of overhanging gold lamps.

Classified is open from breakfast through dinner and will serve brunch on weekends starting in October. It has an extensive wine and spirits list with many high-end choices such as a 30-year-aged scotch from the Macallan, which runs $125 for an ounce-and-a-half pour.