How Notam works, the system whose breakdown delayed 8,700 flights in the US

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Before taking off, pilots need to know what they’re going to find along the way. The Notam communication system helps with this: short bulletins inform about runway closures, signal failures and possible obstacles in the air.

On the morning of this Wednesday (11), however, Notam stopped working in the United States, which generated the biggest stoppage of flights in the USA since the attacks of September 11, 2001.

Initial information points out that the system began to become unstable on Tuesday night (10). This made the FAA (Federal Aviation Authority) suspend all domestic takeoffs in the country at 7:30 am (9:30 am in Brasilia on Wednesday (11).

Departures resumed 90 minutes later, but flights were impacted for the rest of the day. The expectation of authorities and companies is that the situation will normalize by Thursday (12) or Friday (13).

By the end of the afternoon, the breakdown had caused delays in more than 8,700 flights, and at least 1,100 were canceled according to the FlightAware website. There were scenes of chaos in several American airports, with anxious passengers and no information on how they would travel.

The White House said there was no evidence that the flaw was caused by a hacker attack and that the causes of the problem were being investigated. “The FAA is working aggressively to get to the root causes of the system’s failure so that it doesn’t happen again,” said Karine Jean-Pierre, a spokeswoman for the Joe Biden administration.

Notam stands for Notice to Air Missions. Before, it called Notice to Airmen (notice to airmen, in free translation), which generated complaints of exclusion to women.

More than a system in itself, Notam is a communication model: they are short bulletins, similar to a telegram. They bring codes that are easily understood by professionals in the field, but say nothing to a layman. An example:

Q) SBRE/QNDAS/IV/BO /E /000/999/1449S03902W040
DME YLH CH87X U/S

Alerts are issued by airports and aviation authorities. “Classic examples are reductions in the length of the runway due to works, modifications in air traffic control procedures, in the status of fire service available at the airport, in the supply of aircraft, etc”, points out Julio de Souza Pereira, assistant director of safety of IATA (International Air Transport Association) in Brazil.

The notices are also used to warn of radio system failures in an area, military exercises that impact airspace, birds flying in flocks, the presence of ash from volcanoes and restrictions adopted because of the presence of heads of state, among many others. themes.

The system was standardized in 1947, the year in which an international civil aviation convention was held in Chicago, which defined many of the industry’s rules that are still in force.

The convention determined that the government of each country is responsible for centralizing and making available the Notam bulletins. The reports are public and are available on the internet and in closed systems. Data from all countries can be accessed on aviation-specific communication networks such as AFTN and AMHS.

In Brazil, Notam bulletins are centralized by Decea (Department of Air Control), an agency linked to the Brazilian Air Force and which has 12,000 employees. In the 24 hours prior to the publication of this report, the Brazilian system had issued 22 alerts. They can be read here.

“These systems are very robust with several backups and contingency servers, depending on the impact caused by a possible downtime, as happened today in the US. That is why there is no news of problems of the same nature”, comments Pereira.

In the United States, the system is under the control of the FAA, a civilian body linked to the Department of Transportation — equivalent to a ministry in Brazil. The department is headed by Secretary Pete Buttigieg, a Democratic politician who ran in presidential primaries in 2020 and is tipped to run for the White House in the future.

The FAA, however, has had an interim director since March. Biden nominated Phillip Washington for the job, but he needs to be approved by the Senate, which has made it difficult to confirm several of the president’s nominations. The nominee is still waiting to go through the sabbath.

The Biden nominee currently heads the Denver airport and previously led the Los Angeles Urban Transportation Authority. He is the target of investigations for corruption and criticized for having little experience in aviation.

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