Air Canada says 20,000 customers may have had personal information improperly accessed The airline says there was a breach of its mobile app The company says Aeroplan numbers, passport numbers and birth dates could have been accessed There is a lock on all 1.7 million accounts until consumers change their passwords The airline says credit card information is encrypted and protected from the breach Air Canada says it tried to block the hacking attempt Affected users have received an email with instructions on reactivating their accounts