Air travel across the U.S. was thrown into chaos on Wednesday after a cascading outage in a government system grounded the world’s largest aircraft fleet for hours, delaying or canceling thousands of flights.
The cause of the outage is not yet known. While the White House initially said there was no evidence of a cyber attack, President Joe Biden said Wednesday morning that he’d directed the Department of Transportation to investigate.
Whatever the cause, the outage revealed how dependent the world’s largest economy is on air travel and how dependent air travel is on an antiquated computer system called the Notice to Air Missions, or NOTAM.
Before commencing a flight, pilots must consult NOTAMs, which list potential adverse impacts on aviation, from runway construction to the potential for icing. This system used to be telephone-based, with pilots calling dedicated flight service stations for the information, but it has moved online.
According to FlightAware’s flight tracking website, the NOTAM system broke down late Tuesday, leading to more than 1,100 flight cancellations and 7,700 delayed flights by midday Wednesday.
The chaos is expected to grow as backups compound. More than 21,000 flights were scheduled to take off in the U.S. on Wednesday, primarily domestic trips, and about 1,840 international flights were expected to fly to the U.S., according to aviation data firm Cirium.
This caused significant disruptions at airports across the country, with Chicago, Los Angeles, New York and Atlanta seeing between 30% and 40% of flights delayed.
Transportation Secretary Pete Buttigieg said in an interview on CNN, “We are going to see the ripple effects from that, this morning’s delays through the system during the day. Now we have to understand how this could have happened in the first place. Why the usual redundancies that would stop it from being that disruptive did not stop it from being disruptive this time.”
Longtime aviation insiders could not recall an outage of such magnitude caused by a technology breakdown. Some compared it to the nationwide airspace shutdown after the terror attacks of September 2001.
Tim Campbell, a former senior vice president of air operations at American Airlines and now a consultant in Minneapolis said, “Periodically, there have been local issues here or there, but this is pretty significant historically.”
Campbell went on to express concern about the Federal Aviation Administration’s technology, not just the NOTAM system, “So much of their systems are old mainframe systems that are generally reliable but they are out of date,” he said.
John Cox, a former airline pilot and aviation safety expert, said there had been talking in the aviation industry for years about trying to modernize the NOTAM system. However, he was unsure about the age of the FAA’s servers and couldn’t say whether a cyber attack was possible. “I’ve been flying 53 years. I’ve never heard the system go down like this,” Cox said. “So something unusual happened.”
The FAA acknowledged that the NOTAM system failed at 8:28 p.m. Eastern on Tuesday, preventing new or amended notices from being distributed to pilots. The FAA resorted to a telephone hotline to keep departures flying overnight, but as daytime traffic picked up, it overwhelmed the telephone backup system.
In response to this, the FAA ordered all departing flights grounded early Wednesday morning, affecting all passenger and shipping flights. Some medical flights could get clearance, but the outage did not impact military operations or mobility.
President Joe Biden said that he was briefed by Buttigieg, “I just spoke to Buttigieg. They don’t know what the cause is. But I was on the phone with him about 10 minutes,” Biden said. “I told him to report directly to me when they find out,” Buttigieg assured the public that the order to ground all departing flights was done out of an abundance of caution.
This disruption serves as a harsh reminder of how dependent our economy and daily lives have become on air travel and how it can be severely impacted by outdated and fragile technology. The government’s investigation must determine the root cause of the problem to prevent it from happening again and to consider modernizing these systems to avoid such a large-scale disruption in the future.