FLAG Atlantic-1 (FA-1)

FLAG Atlantic-1 (FA-1): Transatlantic Cable Connecting the U.S. and Europe

FLAG Atlantic-1 (FA-1) is a submarine telecommunications cable system connecting the United States, the United Kingdom, and France, spanning 14,500 kilometers across the Atlantic Ocean. Owned by FLAG, it has been listed as in service since 2001 according to GeoCables data. Its landing points include Island Park and Northport in the United States, Skewjack in the United Kingdom, and Plerin in France. While the cable's design capacity, fiber pair count, supplier, and technology details are not publicly disclosed, its existence underscores the importance of transatlantic connectivity for global telecommunications. What makes FA-1 particularly interesting is the uncertainty surrounding its technical specifications and the discrepancies in latency measurements. Publicly available data does not confirm its design capacity or technology, and live latency measurements show artifacts that fall below the theoretical physical floor, illustrating the challenges of accurately assessing submarine cable performance using remote probes.

Quick facts

Name	FLAG Atlantic-1 (FA-1)
Length	14,500 km
Ready for Service (RFS)	2001
Owner	FLAG
Status	In service
Design Capacity	Not disclosed
Fiber Pairs	Not disclosed
Supplier	Not disclosed
Technology	Not disclosed
Landing Points	Island Park (United States), Northport (United States), Plerin (France), Skewjack (United Kingdom)
Computed Latency (One-Way)	71.1 ms
Computed Latency (RTT Floor)	142.2 ms

Route

FLAG Atlantic-1 connects four landing points: Island Park and Northport in the United States, Skewjack in the United Kingdom, and Plerin in France. This transatlantic corridor is a well-established route for submarine cables, linking North America to Europe. The cable’s endpoints are strategically located near major metropolitan areas, ensuring reliable connectivity to regional and global networks.

Why it was built and what it carries

FA-1 was built to provide high-capacity transatlantic telecommunications services, meeting the growing demand for data transmission between the United States and Europe. While specific details about its design capacity and technology are not publicly disclosed, cables in this corridor typically carry internet traffic, private network data, and other telecommunications services. Its construction aligns with the broader industry trend of expanding global connectivity and redundancy.

History: what can be established

GeoCables data lists FA-1 as ready for service in 2001. If industry sources suggest a different year, such discrepancies could arise from delays in commissioning, phased activation of segments, or differing definitions of "ready for service." Without corroborating documentation, the 2001 date remains the most reliable reference.

Capacity and technology

Publicly available sources do not disclose FA-1's design capacity, fiber pair count, supplier, or technology. Speculating on these parameters without operator documentation would be inappropriate. Given its length and era of construction, it likely employs optical amplification and wavelength division multiplexing (WDM), but this cannot be confirmed without further evidence.

Latency: the physics

The computed one-way light propagation latency for FA-1 is approximately 71.1 milliseconds over its 14,500 km length, with a theoretical round-trip time (RTT) floor of 142.2 milliseconds. Real-world latency is higher due to land tails, terminal equipment, and routing overhead. Live measurements from remote probes show several artifacts, with minimum values below the physical floor. For example, Island Park to Plerin reports a minimum of 10.6 ms, which is physically impossible for the cable alone. Such anomalies are likely caused by rate-limited ICMP replies from intermediate routers and should not be interpreted as actual cable performance. The average latency values, such as 92.1 ms for Island Park to Plerin, better reflect the full internet path but still include non-cable factors.

Redundancy: what happens if it breaks

In the event of a failure, redundancy in the transatlantic corridor is provided by other cables connecting the United States and Europe. These include systems such as TAT-14, AEConnect, and Dunant, among others. Repairing FA-1 would involve standard industry practices, including deploying cable ships for fault localization, retrieval, and splicing. Repairs can take weeks depending on the fault’s location and weather conditions.

Bottom line

• FLAG Atlantic-1 (FA-1) is a 14,500 km transatlantic submarine cable connecting the United States, the United Kingdom, and France.
• It has been listed as in service since 2001, though technical specifications are not publicly disclosed.
• Computed latency suggests a theoretical RTT floor of 142.2 ms, but live measurements show artifacts below this value.
• Redundancy is provided by other transatlantic cables, and repairs follow standard industry practices.
• Publicly available data does not confirm its design capacity, fiber pair count, supplier, or technology.