It’s always best to stay on a flight attendant’s good side, whether you’re angling for extra Biscoff cookies or just hoping to make someone’s day at work as painless as possible. To keep them smiling while you’re in the sky, there’s one faux pas you’ll definitely want to avoid—and it could save you from some serious embarrassment as well.

According to the travel experts at Alpine Elements, as reported by The New York Post, flight attendants hate it when passengers don’t lock the bathroom fully when inside or shut the door fully upon their exit.

Unlocked doors can cause confusion among passengers and sometime leads to long lines of people waiting for a toilet that is actually available. The line blocks aisles and work spaces that flight attendants need to serve passengers and keep them safe. Travelers should always make sure that bathroom latches are completely closed so the lavatory is shown as “occupied” on the lights outside in the cabin.

Proper bathroom etiquette on planes can also be important for safety reasons. Failing to lock or close the bathroom door can be a concern, as flight attendants need to know which spaces are available and which are occupied in the case of an emergency. Locking properly also prevents other passengers from walking into an occupied lavatory, avoiding both hygiene issues and embarrassment.

“When the door lock isn’t engaged properly, people can walk in on someone by accident. It’s embarrassing for everyone involved and wastes valuable time, especially when there’s a queue during busy periods,” a senior cabin crew member told The Mirror. “Passengers don’t always [realize] the impact of their actions in such a confined space.”

There’s other important bathroom etiquette travelers should keep in mind to avoid bothering flight attendants. Try not to use excessive amounts of water, since aircrafts only have a limited supply onboard and running taps can waste it. Cabin crews also get frustrated by passengers flushing inappropriate items, like wet wipes, which clog airplane toilets. Instead, make sure to put everything that isn’t toilet paper in the trash. Also, using the bathroom for non-essential purposes and occupying the space for an extended period can cause lines—and headaches for the crew.

Staying in flight attendants’ good graces is all about staying aware and respectful during the time you’re sharing these small spaces in the sky. Next time you’re in the air, take an extra second to make sure the bathroom door is properly locked and closed as needed. Everyone on board will thank you.

Read the original article on Travel & Leisure