Nearly 100 million Americans will travel this holiday season, including airline passengers and drivers, according to Generali Global Assistance‘s travel insurance division.

More than 6.4 million alone are expected to travel by air.

AirHelp, an air passenger rights organization and flight compensation company, looked at data from hundreds of thousands of flights from the 2016 holiday season to help inform travelers what to expect during this year’s holiday season.

The organization lists the top five most disrupted routes, along with the percentage of flights disrupted: San Francisco (SFO)–Los Angeles (LAX) with 53 percent of flights disrupted; Las Vegas (LAS)–Los Angeles (52 percent); Los Angeles to Las Vegas (48 percent); Seattle (SEA) to Los Angeles (48 percent); and Los Angeles to San Francisco (46 percent).

AirHelp also found the Friday before Christmas is the busiest travel day, but the day varies per airport. The busiest overall airports are Atlanta (ATL), Chicago (ORD), Los Angeles, Dallas (DFW), Denver (DEN), Charlotte (CLT), Houston (IAH), New York (JFK), San Francisco and Newark (EWR). Previous years show Dec. 23 to be the busiest day for San Francisco, Houston, Charlotte, Denver and Chicago, while Dec. 26 is the busiest for Atlanta; and Newark and New York see the highest number of passengers Jan. 2.

While insights such as these are helpful and extra time should be allotted when traveling during the holidays, there are always factors beyond our control. At Hartsfield-Jackson Atlanta Airport last week, for example, an 11-hour power loss caused more than 1,000 canceled flights. Here are some tips to keep in mind to be prepared for expected and unexpected travel troubles.