On May 14th, aUnited Boeing 787-9 flying from Hong Kong towards San Francisco experienced a cracked windshield several hours after takeoff. The incident forced the aircraft to divert to Tokyo Narita just after midnight on May 15th.

United Airlines 787
United Airlines MileagePlus miles won't expire. Photo: United Airlines

Flight details

The United Airlines Boeing 787-9 involved had registration N26952 and was performing flight UA-2862, flying from Hong Kong to San Francisco. According to the Aviation Herald, the aircraft was originally scheduled to depart the day before - on May 13th. However, the aircraft's actual departure took place on May 14th - approximately 21 hours after its scheduled departure.

With four crew on board, the aircraft was en route at FL400 over the Pacific Ocean about 470nm east of Tokyo Narita Airport (Japan). It was in this area that the crew decided to declare PAN PAN reporting a crack in the captain's windshield.

For those unaware, a PAN PAN is an international radio distress signal of less urgency than a mayday signal.

UA2862 flight
The aircraft diverted to Tokyo Narita International Airport after the incident took place. Photo: FlightRadar24.com

The aircraft then turned around, maintaining FL400 and diverting to Tokyo Narita. A safe landing was made on runway 16R, about 90 minutes after the PAN PAN on May 15th, just past midnight.

Currently still at Tokyo Narita Airport, the 787-9 is scheduled to fly onwards to San Francisco on May 16th at noon, local time.

N26952's interesting journeys

According to FlightRadar24.com, the aircraft involved in this latest incident has been flying some interesting fifth-freedom routes lately. This was the aircraft's journey between May 8th and May 10th:

  • San Francisco - Tokyo
  • Tokyo - Chengdu
  • Chengdu - Tokyo
  • Tokyo - San Francisco

Then on May 10th to 11th, the aircraft made a similar journey, but instead went to Beijing instead of Chengdu:

  • San Francisco - Tokyo
  • Tokyo - Beijing
  • Beijing - Tokyo
  • Tokyo - San Francisco

This latest flight was part of a fifth-freedom service going from San Francisco to Hong Kong to Singapore. With increased travel restrictions these days, the main purpose of these flights is for cargo.

What causes a cracked windshield?

There are several reasons as to why aircraft windshields may crack. Designed to withstand huge variations in temperature and pressure, windshields are made of several layers that are designed to be extra durable. These layers include reinforced glass, various types of plastic, and even a thin layer of metal that conducts an electric current to keep the windshield free from ice. The glass should be able to withstand the impact of a bird strike.

However, the windshield is not completely indestructible. In fact, windshields may suffer cracks for a variety of reasons, including severe hailstorms and incorrect heating. This occurs with modern aircraft that have electronically heated windows. The glass sometimes cracks due to a short-circuit. The age of the aircraft and the number of flight cycles can also be a factor due to stress levels put on the glass over a long period of time.

United Airlines 787 aircraft
United has previously warned staff that if too few people took voluntary leave packages, it would need to furlough staff in October. Photo: United Airlines

Have you ever been on a flight that has suffered a cracked windshield? Share your experience with us in the comments.

Simple Flying contacted United Airlines and requested a statement and additional information. At the time of publication, we have yet to receive a response from the airline. We will update this article if any new information is received.