More burgers and fries are coming to the skies

Delta Air Lines and Shake Shack want more people to get high and eat junk food. Following a limited test run in Boston, the pair last month expanded a partnership where the restaurant chain’s burgers are served to first-class passengers on the airline’s flights.

They’ve been pretty popular: Between December and March, Delta served 10,000+ first-class burgers. They now account for ~15% of the ~4,500 hot meals prepped daily at the company’s Atlanta flight kitchen.

It’s not just Delta: American Airlines also last month expanded its limited test of serving sliders and fries in the skies.

Airplane food is actually getting good

As North American carriers began to compete more directly with Asian, European, and Middle Eastern airlines with reputations for top-tier customer experiences, they started offering more premium food options in first class (often curated by celebrity chefs), Bloomberg reports.

• United now offers Magnolia Bakery banana pudding, while Alaska serves Stumptown coffee, Beecher’s cheese, and Salt & Straw ice cream.

But…There are limitations. The food has to be cooked ahead of time, chilled to a safe temperature, then reheated in the air—making items like avocado toast nearly impossible to get right without turning them soggier than paper towel tossed into a pool.

Big picture: This premium food push comes amid a broader premium passenger push, as airlines increasingly cater to those willing to shell out cash for a more elevated flying experience.