Air passengers in Canada are contending with epic waits in screening lines at airports, both to get on planes and, for international travellers, to get into the country.

Here’s what’s going on.

On the way out: The Vancouver airport warned travellers last week that security screening waits can be extremely long and passengers should arrive hours early. Pearson airport in Toronto is having similar problems.

The Canadian Air Transport Security Authority, the federal agency responsible for pre-flight screenings, is short of staff, YVR said. CATSA acknowledged the trouble, blaming its contractors’ difficulty finding workers and passengers’ decisions to bring more carry-on bags.

On the way in: Pearson, in particular, is also seeing backlogs at international arrivals, which the airport authority ascribes to COVID-19 screenings carried out by the Canada Border Services Agency.

“While pre-pandemic it took a CBSA officer on average 30 seconds to process an international arriving passenger, today the process can take at least one to two minutes—two to four times longer,” spokesperson Tori Gass told The Logic in an email.

Sometimes passengers are kept on their planes to avoid overcrowding in the arrivals hall, she added. This is happening with about 30,000 international arrivals daily, Gass said, a number the authority expects will soon rise to 45,000.

Vancouver and Calgary airports said they’re having no problems with international arrivals. Montreal’s Trudeau airport has had some trouble but reports “major improvement in fluidity” since the federal government loosened COVID-19 rules for incoming travellers on April 1.

The consequences: “WestJet is concerned with the state of services provided by government agencies at our air borders and security screening points and we are diligently working with the appropriate officials to stress the urgency of the situation given the rapidly increasing number of guests returning to travel this summer,” WestJet spokesperson Madison Kruger said in an email. Clogs “affect the entire travel and tourism ecosystem.”

What’s being done: “At Transport Canada we’re conveying our sense of urgency to CATSA and we’re offering cooperation and support to work with them on making sure that we respond quickly to this surge of travel need,” Transport Minister Omar Alghabra said in a Parliament Hill scrum Tuesday when asked about the problems for outbound flyers.

CATSA has apologized and said it’s leaning on its staffing contractors to hire more people.

The CBSA refused to answer questions about its staffing for arrivals at Pearson, citing security. Spokesperson Rebecca Purdy (who has previously shared incorrect information) said the agency “takes appropriate measures to ensure that there are sufficient resources available to adequately manage the border and allow for the ability to increase operational flexibility and respond to service demands as and when required.”

But Purdy also said sometimes a convergence of flights arriving at once, plus more intensive screening, mean “travellers to Canada should expect longer border wait times.”

The Toronto airport authority wants further streamlining of COVID-19 screenings, including moving the spot-check tests still required of some travellers out of the airport, Gass said.

WestJet endorsed that and also wants to see the government “investing in the necessary government agency staffing and technology to achieve globally competitive service level standards,” Kruger said.