American Airlines was forced to delay multiple flights on Tuesday night after the iPad app used by pilots crashed.

Introduced in 2013, the cockpit iPads are used as an “electronic flight bag”, replacing 16kg (35lb) of paper manuals which pilots are typically required to carry on flights. They are used to distribute information such as flight plans throughout the airline’s fleet.

But the app that replaced the flight bag crashed on Tuesday, affecting multiple planes scattered throughout the entire fleet, according to passenger reports, leaving the pilots unable to take off. “The pilot came on and said that his first mate’s iPad powered down unexpectedly, and his had too, and that the entire 737 fleet on American had experienced the same behavior,” one passenger told business news site Quartz. “It seemed unprecedented and very unfamiliar to the pilots.”

An American Airlines spokesperson confirmed the issue, telling the Verge: “Some flights are experiencing an issue with a software application on pilot iPads … In some cases, the flight has had to return to the gate to access a Wi-Fi connection to fix the issue. We apologise for the inconvenience to our customers.

“We are working to have them on the way to their destination as soon as possible.”

Another spokesperson said that the issue affected “a few dozen flights” across the airline.

When the electronic flight bags were introduced, American Airlines proudly detailed the environmental and cost-savings impact of the change. “Removing the kitbag from all of our planes saves a minimum of 400,000 gallons and $1.2 million of fuel annually based on current fuel prices,” said the company’s head of safety and operations performance, David Campbell.

“Additionally, each of the more than 8,000 iPads we have deployed to date replaces more than 3,000 pages of paper previously carried by every active pilot and instructor. Altogether, 24 million pages of paper documents have been eliminated.”

The glitch in the electronic flight bags comes in the same month that a US watchdog warned of the possibility of in-flight Wi-Fi being used to hack into the avionics system of a plane. The Government Accountability Office warned that: “Modern aircraft are increasingly connected to the internet. This interconnectedness can potentially provide unauthorized remote access to aircraft avionics systems.”

A week later, a security researcher was barred from a United Airlines flight after he tweeted about attempting to hack the passenger oxygen controls on his flight.

Find myself on a 737/800, lets see Box-IFE-ICE-SATCOM, ? Shall we start playing with EICAS messages? "PASS OXYGEN ON" Anyone ? :) — Chris Roberts (@Sidragon1) April 15, 2015

Chris Roberts was forced to find another flight to San Francisco following the ill-advised tweet.