Westjet, Canada's second-largest airline, said the personal information of 1.2 million passengers was stolen earlier this year in cyberattacks and data breaches.
The airline has revealed the number of passengers affected by a submission to the Maine Attorney General.
According to the notice, the stolen data may include passenger names, date of birth, postal address, and travel documents including passports and government-issued identity documents, as well as other passenger accommodations such as requests and complaints.
Westjet said information related to customer compensation may also be taken, such as point balances and other information related to compensation accounts.
The Canadian airline giant disclosed a security case in June after discovering that the system was compromised and hackers stole data from the network.
Westjet spokesman Jennifer Booth did not answer TechCrunch's questions regarding the violation when received via email.
Media reports linked to a hacking group known as Spiders who scattered Westjet violations. This is a financially motivated group of English-speaking teens and young adults who are known to train them to help desks and employees to grant access to the corporate network.
Earlier this year, the FBI and cybersecurity companies warned that hackers were targeting the transportation and aviation industry. The Australian airline Qantas is said to have been hacked by the same group, and personal information from more than 6 million customers was stolen.