Travis Barker’s making the most of his first trip via airplane in 13 years by enjoying his new favorite thing … getting frisky with Kourtney Kardashian.

The couple’s currently on vacation in Cabo, and from the looks of things — have picked up right where they left off in the States … with no shortage of PDA.

We’re told they were together for a while in the pool at the Las Ventanas al Paraiso resort and making out … while enjoying tropical drinks in the agua.

Kourtney and Travis are staying in a very secure spot at the hotel, but they’re clearly mingling with other guests in the main pool.

Barker’s trek to Mexico with his girlfriend — along with Kris Jenner and Corey Gamble — was his first time flying since the deadly 2008 plane crash that killed 4 people and left him with third-degree burns on 65 percent of his body.

After the crash — in which the Blink-182 drummer lost 2 of his close friends, Charles “Che” Still and Chris Baker — he vowed to never fly again … but recently said he might give it another try.

That’s exactly what he did this past weekend, and he’s crediting Kourtney with helping him get there … saying, “With you anything is possible.”