Enlarge / An air traffic control tower is seen at JFK airport on January 11 in New York City. (credit: Michael M. Santiago/Getty Images )

Late in the evening of Jan. 10, 2023, an important digital system known as NOTAM run by the Federal Aviation Administration went offline . The FAA was able to continue getting necessary information to pilots overnight using a phone-based backup, but the stopgap couldn’t keep up with the morning rush of flights, and on Jan. 11, 2022, the FAA grounded all commercial flights in the U.S. In total, nearly 7,000 flights were canceled. Brian Strzempkowksi is the interim director of the Center for Aviation Studies at The Ohio State University and a commercial pilot, flight instructor and dispatcher. He explains what the NOTAM system is and why planes can’t fly if the system goes down.

Late in the evening of Jan. 10, 2023, an important digital system known as NOTAM run by the Federal Aviation Administration went offline . The FAA was able to continue getting necessary information to pilots overnight using a phone-based backup, but the stopgap couldn’t keep up with the morning rush of flights, and on Jan. 11, 2022, the FAA grounded all commercial flights in the U.S. In total, nearly 7,000 flights were canceled. Brian Strzempkowksi is the interim director of the Center for Aviation Studies at The Ohio State University and a commercial pilot, flight instructor and dispatcher. He explains what the NOTAM system is and why planes can’t fly if the system goes down.

What is NOTAM?

Aviation is full of acronyms, and Notice to Air Missions, or NOTAM, is one acronym that pilots learn early on in their training. A NOTAM is quite simply a message that is disseminated to flight crews of every aircraft in the US.

Enlarge / As of 7:30 am Eastern, all domestic flights have been grounded due to a NOTAM outage. (credit: Getty Images)

Today might not be the best day to fly. Earlier this morning, the Federal Aviation Administration suffered an outage to its Notice to Air Missions system . Better known as NOTAMs, these provide information to pilots about potential hazards along their routes, including temporary flight restrictions such as a rocket launch or air show, perhaps.

Consequently, flight operations across the US have been affected. At first individual airlines delayed flights, but at 7:19 am Eastern the FAA announced a nationwide pause in all flight departures until 9 am Eastern time.

Update 3: The FAA is still working to fully restore the Notice to Air Missions system following an outage.⁰⁰The FAA has ordered airlines to pause all domestic departures until 9 a.m. Eastern Time to allow the agency to validate the integrity of flight and safety information.

— The FAA (@FAANews) January 11, 2023

Both American Airlines and United confirmed they were experiencing flight disruptions this morning.

Enlarge / Airbus 320 cockpit. (credit: Getty Images | Skyhobo )

The Federal Aviation Administration says it finally has a plan for the industry to replace or retrofit airplane altimeters that can't filter out transmissions from outside their allotted frequencies. The altimeter problem has prevented AT&T and Verizon from fully deploying 5G on the C-Band spectrum licenses the wireless carriers purchased for a combined $69 billion .

The FAA was urging airlines to retrofit or replace altimeters in recent months and now says it has finalized a plan. An FAA statement on Friday said that "airlines and other operators of aircraft equipped with the affected radio altimeters must install filters or other enhancements as soon as possible."

AT&T and Verizon said they will be able to accelerate 5G deployments near airports in the coming months, but the carriers agreed to continue some level of "voluntary mitigations" in the airport areas until July 2023.

Enlarge / SpaceX's next rocket on site at Boca Chica. (credit: Getty Images / Washington Post )

On Monday, the Federal Aviation Administration (FAA) gave SpaceX one of several approvals that will be needed before the company can launch its Starship from the Boca Chica site in South Texas. The environmental approval comes in part because technology developments have allowed the company to eliminate some of the facilities initially planned for the location, greatly reducing its footprint and impacts.

Still, the company will face restrictions within the site and timing of the launches; it will also be expected to support some environmental and historical interests. The company will still need the FAA's approval regarding safety and risks before it can begin operations.

Less is more

SpaceX has been pursuing atmospheric testing of its hardware at Boca Chica. Ultimately, it plans to turn this into the main launch site for the Falcon Superheavy vehicles that will loft its Starship vehicle into orbit, along with potential commercial cargo. The booster would also potentially return to the site or land offshore and be ferried back.

Enlarge (credit: Getty Images | BackyardProduction)

The Federal Aviation Administration is reportedly urging airlines to retrofit or replace altimeters that receive transmissions from outside their allotted frequencies. The FAA is meeting Wednesday "with telecom and airline industry officials on a push to retrofit and ultimately replace some airplane radio altimeters that could face interference from C-Band 5G wireless service," Reuters reported Tuesday .

The Reuters report continued:

The FAA wants to use the meeting to establish "an achievable timeframe to retrofit/replace radar altimeters in the US fleet," according to a previously unreported letter from the FAA's top aviation safety official Chris Rocheleau reviewed by Reuters. It also asked aviation representatives "to offer options and commit to actions necessary to meet these objectives."

Some altimeters used by airplanes to measure altitude apparently cannot filter out transmissions from C-Band frequencies assigned to wireless carriers for 5G. Altimeters are supposed to use frequencies from 4.2 GHz to 4.4 GHz, while wireless carriers' C-Band licenses are for 3.7 to 3.98 GHz.