In a statement to The Wall Street Journal, a United spokesperson said that the company is planning to “look at every aspect of this diversion to understand what we could do better.” The response came just days after the passengers were forced to sit on the airfield for 12 hours before another airplane picked them up to return them to the Newark airport.

United Flight 179 was set to carry passengers from Newark to Hong Kong before it was forced to make a stop in Newfoundland, Canada following a passenger’s medical emergency. Prior to departure, the plane suffered a mechanical issue that didn’t allow one of the plane’s doors to work. And because the passengers were now in Canada, with no way to clear customs because the airport didn’t have border control working at night, United (UAL) had no choice but to keep them on the plane until help arrived.

For about 12 hours, passengers sat on the plane in the cold waiting for help. Soon, passengers ate through much of the food on the flight, forcing United to have food delivered. Even the flight’s captain had enough and read aloud United CEO Oscar Munoz’s e-mail address. The captain told passengers to e-mail the chief executive and explain their frustration.

A replacement aircraft eventually landed and brought the passengers back to Newark, but the incident caused more than a little displeasure and criticism both from passengers and on social media.

The United spokesperson didn’t say what, if anything, the company would do after its review is complete.

“We apologized to our customers for this experience—our crew and operations did everything possible to assist customers during this delay,” a United spokesperson told Fortune in a statement.