Aviation Herald reported yesterday that a Lufthansa Airbus A321-131 flying from Dublin to Munich was diverted twice en-route due to cabin depressurization. The aircraft, registered D-AIRW, is 22 years old and sports Star Alliance livery.

A Lufthansa A321-131 on the runway
The aircraft descended after a loss of cabin pressure. Photo: Curimedia/Wikimedia

Flight LH-2515 was forced to land twice on its route from Dublin to Munich on 3rd August due to a loss of cabin pressure.

The flight took off with a known fault in the left pack/Pressurisation Air Conditioning Kit, one of two packs which are responsible for maintaining cabin pressure. The right pack then failed shortly into the flight at 34,000 feet, after which altitude was reduced to 11,000 feet and the aircraft was redirected towards Manchester Airport.

Following another redirection to London Heathrow, LH-2515 waited at the airport for three hours whilst it was checked over. Another attempt to reach Munich fell short as the aircraft was once again redirected and forced to land, this time at Brussels.

We are awaiting comment from Lufthansa regarding customer complaints about being served by just one member of staff whilst waiting in Brussels.

A common issue?

The plane involved in yesterday’s incident is by no means new, having been in service for 22 years. It is also the second A321 to experience issues within the past two weeks after HK Express flight UO-763 suffered an engine shutdown during its flight from Hong Kong to Phuket on 26th July.

The same week, a Lufthansa A340 also suffered an engine shutdown during its flight from Frankfurt to Tehran, having to return back to Germany after getting as far as Sofia, Bulgaria.

A Lufthansa Airbus A340 on the runway
Many airlines have plans to retire the aging Airbus A340. Photo: Phillip Capper/Wikimedia

So is the cabin depressurization issue a sign of a deeper issue with the Airbus A321? A look at aircraft model safety figures reveals that the A321, classified as part of the Airbus A320 family, is actually one of the safest aircraft classes.

As of December 2017, the A320 family had a fatality rate per million miles of just 0.08. This is a fraction of many other models, for example, the Boeing 737 family, which as of March 2019 sits at 3.08 fatalities per million miles.

Yesterday’s incident appears to have been a spot of bad luck and perhaps a questionable decision to begin the flight with only one working pack.

The dangers of cabin depressurization

Depressurization can happen in a couple of different ways.

The first, sudden depressurization, occurs when an aircraft’s enclosed structure is suddenly damaged. This can happen as a result of a broken window or an open exit and has been known to result in passengers being ejected from the aircraft due to the sudden pressure change.

A Sukhoi Superjet-100 in flight
Cabin depressurization is a reasonably common fault. Photo: Dmitry Zherdin/Wikimedia

The second type, which happens usually as a result of damaged packs or other equipment, results in a more gradual pressure drop. This is the type of depressurization which caused Lufthansa’s Airbus A321 to land twice and also forced an Aeroflot Sukhoi Superjet-100 to return to Moscow during a flight to Samara back in May.

With gradual depressurization, people aboard a plane can succumb to oxygen deprivation and cold if action is not taken quickly. For this reason, a reduction in altitude is usually the first course of action to ensure the crew and passengers’ safety.