While criticism of airline mobile app quality is not out of ordinary, our analysis reveals that passengers' satisfaction with airline app quality is growing.

The average customer rating across Apple App Store and Google Play for the 12 major European airlines included in this study grew from 3.2 to 3.6 (on 1 to 5 scale) between January 2014 and October 2015.

Airlines aiming at increasing personalisation are aware of the importance of mobile apps. However, a prerequisite to unleashing new streams of ancillary revenues through tailored offers is offering an outstanding digital user experience.

The strategy shift towards mobile is well reflected in increased investment in app development, resulting in the average app quality growth, as shown on the graph below.

After a rather flat 2014, app quality has been growing rapidly in 2015 with average ratings increasing from 3.2 to 3.7 for Android and from 3.0 to 3.4 for iPhone apps. This improvement is, however, not equally distributed across airlines.

In the analysis we have included nearly 50,000 ratings (around 20,000 on iOS, the balance on Android) from customers who shared their opinion about the airline apps through a written review.

We have included six full service carriers (one-third of the review) and six low-cost carriers (two-thirds of all reviews). A complete list airlines is visible on the graph below.

The majority of full-service carrier reviewers (55%) use iPhones, while Android users generated more than three-quarters of the low-cost carrier reviews.

Airline Mobile App Quality Leaders

With new versions and bug fixing updates coming every couple of weeks, the airline app user experience changes very dynamically. To find the current leader, rather than browsing through complete app histories we have focused on the most recent reviews (April 1, 2015 - September 30, 2015).

To capture a more dynamic picture we also present average ratings in the previous 12 months (April 1, 2014 - April 1, 2014).

SAS Scandinavian Airlines is a clear leader with average rating 4.2 on both Android and iOS. SAS jumped to the leader position thanks to introduction of famous Scandinavian minimalistic design and a complimentary digital daily newspaper, now available up to 22 hours prior to departure. SAS is also a winner of the biggest improvement category.

British Airways with its well designed and reliable app comes second. Listening to user comments, the airline fixed some minor bugs and improved cheap fare search, increasing already high user satisfaction in the past six months. Although some useful features such as gate notifications and lounge wifi passwords are available on iPhone only, satisfaction is higher among Android users.

Airberlin, although still popular among app users, has lost its leader position to SAS and BA. The minor bug fixing and introduction of Apple Watch check-in have not been enough to stay ahead of the competition.

At the other end of the scale, we find airlines that failed to meet the users' expectations with their latest upgrades. The last spot in the ranking following the biggest decrease in user ratings belongs to Norwegian Air Shuttle. It's worth noting that its CIO moved to the current ranking leader, SAS.

Among other laggards with ratings well below the industry average are Wizz Air and Ryanair (despite a substantial increase in satisfaction of the Android users) , and surprisingly a social media champion - KLM.

The Platform Gap

A majority of carriers discriminate between phone users, offering superior user experience to the most valuable group. Except for the two quality leaders, SAS and BA, and the poorly-performing KLM and Wizz Air, all other airlines choose a favourite phone user group.

Most notably Lufthansa, while taking rather good care of their iPhone passenger group, is clearly neglecting the Android users. The difference in average ratings is greater than one point. iPhone users are the preferred group for most of the full-service carriers who make a choice - only Air France favours Android.

Meanwhile, the low costs focus on their Android apps, with exception of Norwegian which operates mostly in the iPhone-loving Nordic market.

Are LCCs Missing an Opportunity?

Low cost carriers -- digital natives -- are industry leaders in online engagement. However, their desktop performance in not reflected in mobile. Focusing on direct sales and heavily reliant on ancillary sales, European low-cost carriers should devote more attention and resources to improving their mobile app.

Seeking inspiration from the best-in-class is usually a safe solution, but listening to the voice of customers through in-the-wild tests, with a careful analysis of its own and its competitors app reviews, can also help an airline improve the end-user experience.