More than 70 American Airlines flights have been delayed in the past two days after an iPad app used by pilots crashed.

One passenger told the business news site Quartz: "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 behaviour.

An American Airlines spokesperson confirmed the issue: “Some flights are experiencing an issue with a software app on pilot Apple 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.

In 2013, American Airlines became the first airline to have its pilots rely on iPads for flight plans and navigation. Plans get updated all the time, so the company cut down on lots of excess paper. The airline has estimated the paperless program saves the company at least
400,000 gallons of fuel every year. In all, 8,000 iPads replaced 24 million pages of documents.