Budget airlines have long invented absurd fees, but social media lit up this weekend over Wizz Air’s fee for apparently using an ad blocker while buying a ticket on its website.

Noel Philips, a UK-based travel content creator, tweeted his surprise at a confusing surcharge for a ticket he booked for flights on the Hungary-based carrier. A so-called “system surcharge fee” puzzled him.

Philips said that when he questioned the fee, an airline representative said it applies the surcharge if a customer books on their site while using an ad blocker. If a traveler books without the ad blocker or books through its mobile app or call center instead, Wizz charges a smaller “administrative fee.”

The low-cost carrier cryptically describes the “system surcharge fee” on its site as being “applicable to bookings made by automated systems.” The difference in fees with or without involving “automated systems” is commonly about $2.40 (€2), according to a list of fees on the airline’s site.

A search through online forums finds consumers complaining about the fee since February. Their experiences match the ones Philips had, including the response about ad blockers from Wizz Air.

“If it’s for real, it for sure is different,” said Ann Cederhall, a Stockholm-based airline tech consultant with experience in helping airlines with online e-commerce. “It would be most interesting to have Wizz Air explain its rationale.”

A Wizz Air spokesperson told Skift:

“Our website, and information technology systems have security tools protecting us from robotic attacks, such as credential stuffing, screen scraping, distributed denial of service attacks, etc.,” a spokesperson said. “These protections are essential to secure customer’s data, our business, or system’s stability.”

“The use of automations for booking (robots) require additional hosting efforts and for such activities, Wizz Air applies a system surcharge fee,” the company said.

“AdBlockers are not explicitly forbidden, nor triggering our protection to be detected as a robot,” the company said. “But in a very rare situation, due to bugs in the AdBlockers, they can make the browser act unexpectedly, and flagged by our security tools as suspicious. So, just to be sure, we recommend to turn off AdBlockers in case of any issues.”

“The mentioned case is an edge case which could not be replicated neither by other users, nor by the airline. We apologize if this has caused any inconvenience for our customers.”

A Payments Tech Issue?

The carrier might justify adding a higher surcharge as way to recoup the cost of preventing payment fraud.

So-called payer authentication programs, such as pop-up windows branded Verified by Visa and MasterCard’s Secure Code, require card holders to punch in personal passwords. This step adds a second level of proof that a shopper is real and that thieves haven’t stolen the credit card details.

If merchants use one of these programs, card issuers like Visa and Mastercard may accept some of the losses for online fraud. Otherwise, merchants remain liable for the losses as a general rule.

“The pop-up windows for authentication can be blocked if cardholders have installed software to disable pop-ups,” Visa said in its online guidance for companies. “There is also an additional processing fee incurred by the merchant.”

Perhaps Wizz Air faces this fraud prevention problem and has structured its fees to recoup the cost of working around consumer usage of ad blockers. That could explain why Wizz Air is okay with customers booking via a mobile app.

Most consumers using a mobile app must log in, such as by a password or facial recognition. The second verification step reduces the risk of fraud for mobile app purchases.

Mysterious Fee

Of course, it infuriates many consumers when airlines hit consumers with multiple surprise fees after luring them in with a low base price. Yet the practice often is what helps some low-cost carriers make a profit.

Some commenters on Twitter were quick to assume bad intent. Some responded to Philips’ tweet by suggesting the airline wanted to arm-twist consumers into tracking them across sites or to delivering ads targeted to their personal browsing history.

But Wizz Air doesn’t prompt users to disable their ad blockers elsewhere on its site. That lack of messaging undercuts the idea that the carrier cares a lot about the issue.

The carrier also appeared to follow recent European Union privacy regulations for online privacy. It lets consumers decline cookies when using its site, for instance.

Skift will update the story if we hear back from Wizz Air, whose representatives couldn’t be reached by publication time.

UPDATE: This story was updated to include comment from Wizz Air.

Photo Credit: A Wizz Air Airbus A321 aircraft on the runway. Wizz Air