The Federal Aviation Administration has blamed a software upgrade to its next-generation radar system for the hundreds of delayed and cancelled flights from Washington DC airports on Saturday.
"The FAA identified a recent software upgrade at the Leesburg, VA high-altitude radar facility as the source of Saturday's automation problems," the agency said in a statement.
"The agency is working closely with its contractor, Lockheed Martin Corp., to prevent future occurrences. Despite the outage, air traffic controllers safely handled 70 to 88 percent of Saturday's scheduled arrivals and departures at the region's three major airports by using backup systems and procedures."
The problem occurred in the En Route Automation Modernization (ERAM) system that the FAA is installing across its US radar network. The ERAM system coordinates high-altitude radar readings and allows controllers to track 1,900 aircraft at a time, compared to 1,100 with the older Host radar system.
A new software update, installed on Saturday, allowed air traffic controllers to set up windows of frequently accessed information when needed, but the new code wasn't deleting this data when the operator changed the data, and instead stored it in memory. As a result the entire system overloaded and caused massive delays.
Between 11am and 4pm, flights over the nation's capital were either delayed or cancelled. In all, there were 476 cancellations and 492 delays at Washington's three airports before the fault was identified and fixed.
Bear in mind – that's just for flights flying in and out of Washington, but the city is a major international hub and, as a result, thousands of people missed connecting flights to destinations across the US and overseas. Hotels filled up quickly, car rental became difficult, and there were a lot of grumpy passengers broadcasting their anger on social media.
Such software faults are usually ironed out and backup systems in place, but for some reason this upgrade wasn't tested properly. Certainly the ERAM is a big improvement over older systems, but there are still a few kinks to work out it seems. ®