Note: As of Dec. 31, 2017, Quartz is no longer updating this list. Over the three years we were actively monitoring these glitches, we tracked 42 events that disrupted commercial aviation and countless others that were isolated, limited, resulting in no delays in travel. 

It’s hard to fathom the amount of technology needed to keep the commercial aviation industry running. There are systems for ticketing, communication, scheduling, flight plans, pilot information, air traffic, staffing—the list goes on and on. If one system fails, it can wreak havoc on the whole operation. And they fail at a surprisingly high rate.

Recently, these glitches have been cropping up with great frequency. There is no official record of them; the Federal Aviation Administration says the problems aren’t generally under its purview. That makes it difficult to compare the rate of incidents in 2015 to prior years or evaluate if there are systemic issues in need of fixing.

But our examination of all glitches that have been publicly revealed this year suggests that aviation systems in the US, some of which are decades old, are showing the effects of age. In this dashboard, we’re tracking all incidents that disrupted US air travel in any significant way.

Quartz begin tracking these events in 2015. Any technical incident that prevented an airport or airline from operating normally is included. If you know of an incident that’s not included here, please email us.