But the fact that you're on an airplane puts you farther out of the Earth's gravity well, which means you experience less dilation than we do on the surface, and it is this latter effect that dominates when you're on an airplane. So yeah, flying on airplanes makes you age faster than travelling on the surface.

Time technically goes faster on an airplane due to a phenomenon in physics called gravitational time dilation, as predicted by Albert Einstein’s General Theory of Relativity. According to this theory, gravity warps the fabric of space-time; the farther you are from a massive body (like the Earth), the weaker the gravitational pull, and the faster time passes. At a cruising altitude of 35,000 feet, you are significantly farther from the Earth's core than a person on the ground, so your clock ticks slightly faster. However, there is a competing effect from Special Relativity called velocity time dilation, which states that the faster you move, the slower time passes. Because a plane is moving at roughly 500 mph, this effect pulls in the opposite direction. For a commercial flight, the gravitational effect (time speeding up) is slightly stronger than the velocity effect (time slowing down). Therefore, after a long-haul flight, you are technically a few nanoseconds "older" than if you had stayed on the ground. While this difference is far too small for a human to perceive without atomic clocks, it is a real and measurable effect that is even more significant for GPS satellites, which must constantly correct for time dilation to remain accurate.