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Multiple Boeing 787’s Get Grounded In China Due To GPS Issue

At least 15 Boeing 787 Dreamliners are grounded in China due to a glitch with the GPS system. A rollover of the week counting this weekend has led to a bug in the GPS system, and carriers are choosing not to fly until the fault is fixed.

Hainan 787

Several airlines in China operate the Dreamliner. Photo: Wikimedia

When you read that a number of Dreamliners are grounded, you’d be forgiven for thinking it was those pesky turbine blades failing again. But this time it’s not. It’s something even more bizarre.


This weekend, all GPS systems in the world reached an ‘epoch’. This means they ran out of numbers to count the date and time and had to reset to zero. While most resets happened uneventfully, a handful of older devices were affected, causing them to read the time and date incorrectly.

Among these devices were some on board a number of Dreamliners in China. Carriers have now grounded the plane while they await a software fix from Boeing.

What’s the problem?

Despite being almost two decades into the new millennium, this weekend saw a mini ‘Y2K’ event affecting GPS systems worldwide. The devices were set to rollover from week 1024 to week 1, which, according to manufacturers, could have led to a problem.

Air China 787

The grounding is due to a GPS bug. Photo: Wikimedia

The rollover issue is caused by the GPS systems counting in a ten-bit parameter. They start counting at week zero and then reset when they ready week 1,024. As GPS began counting on 6th January 1980, they reset once on August 21st, 1999 and again this weekend, on April 6th.

TomTom and Garmin both issued press releases ahead of the event. TomTom said that if users regularly updated their devices, there would be ‘no need to worry’. They did say that those who neglected to update their sat nav might find it impossible to use.

Garmin also said that users should not worry, and that they had carried out extensive testing which had shown the ‘vast majority’ of devices would not be affected. Those that were affected would show the wrong time and date but should still be usable for navigation.

Overall, the US Department of  Homeland Security were not really concerned, saying that only older GPS systems or those which hadn’t been updated in a while were likely to be compromised. They recommended users perform an update ahead of the weekend to ensure they wouldn’t use functionality. Apparently Boeing didn’t get the memo.

What’s going on?

Right now, there are no less than 15 Dreamliners affected in China, most of which are grounded pending an update to the GPS. Apparently they all think that today is August 22nd, 1999, which is interesting seeing as the 787 didn’t actually exist then.

xiamen 787

At least 15 Dreamliners are grounded. Photo: Wikimedia

According to a memo from the Cybersecurity and Infrastructure Security Agency in the US, ‘a nanosecond error in GPS time can equate to one foot of position error’. Clearly, this is not good if you’re flying an aircraft and are reliant on precise GPS assistance to get to your destination.

There have been no reports of any incidents connected to the rollover bug, and hopefully a simple update will be all that’s required to get the aircraft flying again.


It’s not the first time the 787 program has been dogged with problems. From issues with the engine grounding many aircraft to electrical fires caused by battery problems, it’s been one incident after another for Boeing. Add all this to the current disaster with the 737 MAX program, and it’s clear to see that the US manufacturer has an awful lot to come back from right now.

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