A United Airlines Boeing 777 flying from London to Houston has faced a new Atlantic mid-air scare after a close call with a FedEx jet. The United Airlines aircraft, en route from the United Kingdom to the United States, experienced the scare over the North Atlantic. According to aviation reports, the Boeing 777 briefly lost vertical separation with another Boeing 777 flown by FedEx.

The incident occurred in Canadian-controlled airspace, putting focus on flight safety between Canada, the United Kingdom, and the United States. However, due to the fast action of pilots and the TCAS system, the mid-air scare was quickly resolved. While the Atlantic crossing remains one of the busiest for transatlantic flights, this United Airlines close call has raised serious concerns. As more flights connect London and Houston, this Boeing 777 incident underscores the need for continued safety vigilance over the vast North Atlantic skies.

What Triggered the Mid-Air TCAS Alert?

On June 21, 2025, United Airlines flight UA879, a Boeing 777-224ER, was on its way from London Heathrow to Houston. While cruising over the North Atlantic in Canadian-controlled airspace, the aircraft received a TCAS (Traffic Collision Avoidance System) alert. This happened due to the plane’s sudden approach towards another Boeing 777, operated by FedEx, flying in the opposite direction.

The proximity occurred as a result of a miscommunication with air traffic control. The Canadian controller had issued a CPDLC (Controller-Pilot Data Link Communications) clearance that included a level change to FL360. This unintended altitude instruction caused the aircraft to climb to a height that brought it dangerously close to the FedEx jet.

FedEx Flight Details and the Route Conflict

The FedEx flight, FL10, had departed from Memphis and was headed to Paris Charles de Gaulle Airport. It was also cruising in the opposite direction when the loss of vertical separation occurred. The two jets, both large Boeing 777 aircraft, came within 1000 feet of each other—far less than the standard safe distance maintained during international flights.

The TCAS onboard both jets likely issued Resolution Advisories, prompting evasive action. These automated systems are designed to detect collision risks and issue avoidance instructions to pilots in real-time, typically when human error or controller miscommunication poses a danger.

Immediate Action by Air Traffic Control and Pilots

Once the Canadian controller realised the altitude error, they reacted swiftly. They contacted the United crew via voice communication and instructed them to maintain FL340. At this point, the aircraft had already climbed to FL345. The United pilots promptly responded to the TCAS alert and descended back to their original assigned flight level of FL340.

Thanks to their quick response, vertical separation of 1000 feet between the two aircraft was restored within seconds. Neither aircraft reported any physical damage, and both flights continued safely to their destinations—Houston for United and Paris for FedEx.

The Role of CPDLC in the Incident

CPDLC is a system widely used in oceanic airspace where voice communication is limited. It allows controllers to send clearances and instructions to pilots via data link messages. However, in this case, a misstep in the automated message led to the incorrect level clearance for the United flight.

This incident highlights the potential risks of over-reliance on automated communications without immediate cross-checking. Despite the widespread use of CPDLC in managing transatlantic traffic, it still requires constant human oversight to prevent such errors.

TCAS: The Last Line of Defence in the Skies

The TCAS system performed exactly as intended during this incident. As the United jet began to climb, the system detected the conflict with the FedEx aircraft and issued an advisory. Pilots are trained to respond immediately to such warnings, even overriding air traffic instructions if necessary.

This successful intervention by TCAS and trained crew avoided what could have been a catastrophic mid-air collision. While the system is designed as a last resort, it remains one of the most effective safety nets in commercial aviation.

Why Vertical Separation Matters in International Airspace

Vertical separation is critical to maintaining order and safety in crowded international skies. Aircraft operating in opposite directions must be spaced by at least 1000 feet vertically. This is especially crucial in oceanic zones like the North Atlantic, where aircraft travel along closely spaced tracks known as NAT routes.

The temporary breach in vertical separation between UA879 and FL10, though corrected swiftly, highlights the tight margins pilots and controllers operate within. Even small errors can have major implications, especially in heavily trafficked corridors.

Canadian TSB Investigation and Findings

Canada’s Transportation Safety Board (TSB) is investigating the incident. Preliminary findings confirm that the CPDLC message error caused the climb towards FL360. While the mistake was corrected quickly, the investigation may lead to updated protocols or system safeguards to prevent such incidents in the future.

The TSB commended both flight crews for their rapid and professional response to the situation. Their actions likely prevented a much more dangerous outcome.

Industry Reaction: Calls for Greater Oversight in Oceanic Airspace

Aviation experts are calling for improvements in automation oversight, especially in oceanic control zones. This event has sparked discussions around better training, clearer interface design for controllers, and enhanced TCAS functionalities.

Some experts also suggest the use of redundant communication channels—such as real-time satellite voice backup—to mitigate such risks. The aviation industry continuously evolves its safety standards, and incidents like this often trigger procedural reviews and upgrades.

What Passengers Must Know About Mid-Air Safety Systems

Incidents like this may seem alarming, but they are a testament to how well aviation safety systems function. TCAS is an independent, automatic system that helps crews avoid collisions even when controller errors occur. Pilots undergo extensive training to handle such situations swiftly and safely.

For passengers, it’s a reminder that even in the rare event of a technical or human error, modern aircraft and flight crews are well-equipped to handle emergencies with precision and calm.

Conclusion: A Near Miss That Reinforces Global Aviation Safety

The United Airlines and FedEx near-miss over the Atlantic is a rare reminder of the complexities involved in managing thousands of flights daily across global air routes. Although it was a serious situation, it also demonstrated the robustness of modern aviation systems—from TCAS alerts to rapid pilot response.

As international investigations continue, it’s likely that air traffic protocols will be updated to reduce similar risks. For now, the successful resolution of this incident adds to the long list of lessons that continue to shape safer skies. (TTW)