Travelers hoping for extra privacy have a new option on United Airlines.

Customers can now close the doors to Polaris suites on some Boeing 787-9 aircraft, in international business class.

United debuted the Dreamliners with new Elevated interiors earlier this year, but the privacy doors had been locked in an open position pending certification by the Federal Aviation Administration.

That’s now been granted, and United has begun unlocking the sliding doors. They’re expected to all be unlocked within weeks.

Several other airlines also offer suites with privacy doors, including Delta Air Lines and American Airlines.

United plans to offer similar doors, operable from day one, in its upcoming Airbus A321XLR, but it hasn’t yet announced when those will enter service.

Why do the changes need FAA certification?

All premium seating must meet stringent FAA certification standards to comply with safety and evacuation requirements, according to the federal agency.

Those requirements include flight attendant training on new aircraft seats and safety features, so they can properly instruct passengers in the event of an emergency evacuation.

The FAA notes while premium seats and suites have become more complex in recent years, regulatory requirements have not significantly changed.

United Boeing 787-9 routes with Elevated interior

United currently operates its Boeing 787-9 with Elevated interior between San Francisco International Airport (SFO) and Singapore Changi Airport (SIN), as well as between SFO and London’s Heathrow Airport (LHR).

From September until late October, it will also operate between SFO and Seoul’s Incheon Airport (ICN) and between SFO and Zurich Airport (ZRH).

In late October, the aircraft will begin serving Houston’s George Bush Intercontinental Airport (IAH). It will operate flights between IAH and São Paulo/Guarulhos International Airport (GRU), Tokyo’s Narita International Airport (NRT) and Sydney Airport (SYD).

Service between IAH and Heathrow (LHR) will begin in early January.

The airline expects to have at least 30 Boeing 787s with Elevated interiors by 2027.