Passengers accustomed to flying in United Airlines’ Polaris cabin may find themselves particularly happy or angered this winter season. The airline will expand Polaris service on certain routes and lose the service on others as it rotates aircraft to satisfy seasonal demand to certain destinations.

Here’s a quick summary of what to expect (and when) for United’s popular business class service:

• Los Angeles (LAX) to Shanghai (PVG) flights will operate without a Polaris cabin from December 7 through January 31.
• Newark (EWR) to Barcelona (BCN) flights began operating without a Polaris cabin on October 26.
• Newark (EWR) to Brussels (BRU) flights will operate without a Polaris cabin beginning February 13.
• Newark (EWR) to Hong Kong (HKG) flights will operate without a Polaris cabin beginning December 3.

Now the good news! Here’s a rundown of routes that will gain Polaris service for the winter season:

• Newark (EWR) to Sao Paulo (GRU) will operate with a Polaris cabin beginning December 3.
• San Francisco (SFO) to Frankfurt (FRA) will operate with a Polaris cabin beginning February 12.
• San Francisco (SFO) to Shanghai (PVG) will operate with a Polaris cabin beginning February 13.
• San Francisco (SFO) to Tokyo (HND) will operate with a Polaris cabin beginning January 6.

United continues to outfit its aircraft with the Polaris business class cabin, so while these seasonal changes are a pain point for some at the moment, the airline’s plans to increase this service in the future will allow for plenty of Polaris for everyone!