TORONTO -- More than 1,500 travellers refused to comply with wearing a face mask during their flight and hundreds of letters of non-compliance were issued in 2021 as a result, according to updated data released by Transport Canada.

Fines were issued to 30 passengers as well, data showed. Transport Canada told CTVNews.ca in an email that monetary penalties between $700 to $5,000 were handed out to passengers in 2021.

CTVNews.ca had previously reported that refusing to wear a mask was a leading cause of unruly behaviour on flights in Canada. Incidents rose over the summer in particular, when air travel picked up. But updated data as of Jan. 17, 2022 showed that October and November turned out to be even worse for airlines dealing with passengers refusing to wear a mask. A total of 1,594 incidents during flights were recorded in 2021, including 223 reports in October and 227 in November alone. Data showed that 108 passengers were asked to deplane after boarding due to their non-compliance.

Letters of notification were given to 428 passengers, while another 501 letters of non-compliance were handed out, Transport Canada data showed. The agency said it takes a graduated approach to enforcement action, and a first offense may result in a letter of warning. An “enhanced level of enforcement action†would be taken for subsequent violations of the same offense, but spokesperson Sau Sau Liu said first time violators are not always given warning notices.

“When an investigation finds evidence of aggravating factors, such as blatant and repeated refusals to comply, combined with other inappropriate behaviours such as disrespectful or abusive language on the part of the alleged offender, verbal or physical threats towards employees, crew members or fellow travellers, the Minister of Transport can impose monetary penalties even if on a first offence,†she said.

Law enforcement are called in to intervene in “egregious†violations where passengers are considered “unruly.†“In those circumstances, a monetary penalty can be levied in addition to possible criminal charges,†Liu said.

Previous analysis by CTVNews.ca on unruly passenger events in 2021, as documented on Transport Canada’s civil Aviation Daily Occurrence Reporting System (CADORS), found that more than two dozen incidents involving masks had escalated enough to warrant a report for "unruly" behaviour, but a representative for the Canadian Union of Public Employees (CUPE) said the actual numbers are likely higher.

“There's a lot of paperwork that happens when that kind of incident takes place. So we know for 100 per cent sure that there's a massive underreporting,†Troy Winters, the senior health and safety officer at CUPE, had previously said in an interview in November. Canada’s largest union represents more than 15,000 flight attendants across nine Canadian airlines.

In one CADORS report, a Calgary flight to Halifax carried a passenger who was reported as likely intoxicated, not wearing a mask, and pretending to sneeze on other passengers. The individual also threatened another passenger, according to the report. The traveller, who was labeled as “level 3 unruly,†was handcuffed and taken into custody on arrival. Level 3 is defined by Transport Canada as “an incident where the safety of passengers or crew members is seriously threatened.â€

WestJet, for its part, said in an email on Monday that it has issued travel bans against 163 travellers since instituting a “zero-tolerance†policy on masks in September 2020. That figure represents less than 0.01 per cent of all WestJet passengers, it added. The bans last for 12 months.

South of the border, the U.S. Federal Aviation Authority received a total of 5,981 reports of unruly passenger behaviour and 4,290 reports that were related to masks . A total of 1,081 investigations were launched last year, compared to the 182 initiated on average each year between 1995 and 2020.

While many of the most high-profile incidents of bad behaviour during flights occurred outside of Canada, a to Cancun on Dec. 30 from Quebec made international headlines after videos appeared on social media showing passengers maskless, vaping, and drinking during the flight. The incident is currently being investigated by Transport Canada.