There’s nothing like finally getting comfortable enough to peacefully sleep on your flight only to be abruptly woken up by your flight attendant telling you to put your seat back in the upright position and to put your tray table away. And while it might be a bit annoying, cut your flight attendant some slack. They’re not trying to be a nuisance, it’s simply federal law.

The Federal Aviation Administration requires by law that seats are upright and tray tables are put away during take-off and landing. Statistically from 2012 to 2016, you had a one in 20 million chance of getting in a plane crash. But of that one in 20 million, 58 percent of fatal accidents occurred during take off and landing, according to a Boeing study.

Having your seat back upright and your tray table up means less of a chance that you trip over anyone’s reclined chair or get smacked by anyone’s table. It also reduces chances that your face will end up slammed into the head rest of the seat in front of you during a crash landing. If your own seat is reclined, you’re at more risk for head injuries. Your head will have to travel further back, leading to a hard impact. And If a crash is inevitable and evacuation isn’t possible, passengers will need to brace for impact, which you can only do if you’re sitting up right, according to Britain’s Civil Aviation Authority.

Flight attendant Kat Kamalani explained in a TikTok video that it’s also all about your egress, which is your way out. The space between your seat and the chairs in front of you drastically impacts your access for egress. In the unlikely event that you needed to evacuate, it’s very important that your escape route is clear.

@katkamalani Please don’t be this person… #travelhacks #traveltips #tipsandtricks #didyouknow #shadowandbone ♬ Act 2: In the Hall of the Mountain King – Edvard Grieg

So no need to make a fuss the next time your flight attendant asks you to prepare for landing. Instead, how about a thank you?