Hong Kong-based Cathay Pacific Airlines is investigating how multiple oxygen bottles were found empty on two aircraft at Toronto Pearson International Airport (YYZ) in Canada.

The Oneworld alliance member said it has launched an investigation after a dozen cabin crew oxygen bottles were found either partially or fully empty on two of the airline's aircraft.

Airline staff became aware that the oxygen bottles had been tampered with during routine ground inspections of two Cathay Pacific's planes. One of the aircraft had five bottles that had been tampered with, while the other had eight.

Each of the Cathay Pacific planes was equipped with 22 oxygen bottles

Each of the jets is equipped with 22 oxygen bottles so that the cabin crew can breathe and move about the cabin in an emergency, should the aircraft lose cabin pressure. A loss of cabin pressure would automatically see the deployment of the passenger’s overhead oxygen masks, but crew would have to be reliant on mobile solutions.

This latest incident comes on the heels of protests in Hong Kong, which has seen Hong Kong International Airport close down due to demonstrations. As of yet, the airline has been unable to say who could be behind what appears to be a deliberate act that, if gone undetected, could have proven to be a serious safety breach.

There was never any danger to passengers and crew

Air Transport World quotes Cathay Pacific saying there was never any danger to the passengers and crew because the oxygen bottles are always checked before departure.

Playing down the situation, Cathay Pacific said that it “identified the issue prior to departure during its routine inspections that it carries out before every flight.” They say that the empty bottles “were immediately recharged and checked for serviceability by engineers prior to their flights.”

“At no point was the safety of our crew and passengers compromised,” Cathay said.

Despite making it sound less important than it is, the carrier said it is “taking the issue very seriously and has launched an internal investigation into the matter.”

Cathay Pacific is being watched by the CAAC

Cathay Pacific has been under the spotlight of mainland Chinese aviation regulators amidst the on-going Hong Kong protests.

The Civil Aviation Administration of China (CAAC) just recently issued Cathay Pacific with a new set of safety requirements. One of these new requirements was to submit a report “providing details of actions taken to step up internal safety controls and improve flight safety and security.”

The CAAC also took the hard-line mainland approach telling Cathay Pacific that they would not accept radical behavior from any Cathay Pacific staff member. Now, before any flight over Chinese airspace, the airline must submit a list of the crew members before getting approval.

Cathay Pacific has told the CAAC that they have no problem with the new request. The airline has adopted a zero-tolerance policy towards employees who have taken part in illegal protests.

Up until now, four Cathay Pacific employee’s including two pilots have been fired for actions related to the demonstrations.