Why Do Aircrafts Bound for the US Often Fly Over Canada First?

When planning an international flight, one might assume that the shortest path between point A and point B represents the most efficient route. However, it turns out that for many transatlantic flights heading to the United States, the shortest path involves flying over Canada. This often confusing route not only spans a significant amount of distance, but it also necessitates navigating through airspace controlled by Canada. This article aims to explain why, despite the seemingly less direct path, this route is often preferred.

The Shortest Doesn't Always Mean the Best Route

Consider a flight from London to Chicago. If you were to measure the shortest distance between these two cities on a globe or a map using a string, the string would likely pass over the North Atlantic, just south of Ireland, then over the northern coasts of Canada before crossing Michigan and reaching Chicago. This is known as a great-circle route, which is the shortest distance between two points on a sphere. Curiously, however, this route is not always the one airlines choose.

The Role of Air Traffic Control and International Boundaries

The reason for this discrepancy lies in air traffic control (ATC) and international airspace. Airspace is divided into multiple zones, each controlled by different countries. While the great-circle route is the shortest, airplanes must abide by these air traffic regulations. In the case of flights from the UK to the US, this means navigating through Canadian airspace as part of their journey.

This arrangement is in part due to agreements between countries regarding the use of airspace. For example, Canada has established corridors and routes that are more straightforward and manageable for transatlantic flights. These routes help ensure that flights are processed efficiently and safely, despite the longer distance.

Other Examples of Route Variations

To better understand this concept, let's consider a few examples. A flight from Mexico City to New York does not typically have to fly over Canada since the shortest path involves crossing the Gulf of Mexico directly. For instance, if you were to fly from Mexico City to New York and follow a great-circle route, the plane would head directly towards the Gulf of Mexico before crossing various U.S. states and landing in New York. This is more direct and does not require passing through Canadian airspace.

However, when flying between certain airports in the northeastern United States or Canada, it is not uncommon for planes to fly over the Great Lakes. This is because these regions are controlled by different ATC authorities and can be less congested than central or southern U.S. airspace.

Optimal Flight Paths and Efficiency

While the route over Canada may seem longer, it often proves to be more efficient for several reasons. Firstly, longer routes can provide more time to check for weather changes or other unforeseen circumstances. Additionally, flights over Canadian airspace may encounter less busy air traffic due to different traffic patterns. This allows for smoother and safer flights.

Furthermore, flying over Canada can offer better communication and support for airlines. Canadian ATC is known for being efficient and responsive. This can be particularly important during unexpected events or emergencies.

For example, let's take a hypothetical flight from London to Chicago. Despite the longer path, this route would typically involve minimal delays due to optimize communication and coordination. This is why airlines often opt for this route even though it might seem counterintuitive from a distance perspective.

Conclusion

In summary, while the shortest distance between two points is not always the best route in practice, the flight path over Canada for a transatlantic flight to the U.S. is often a strategic and optimal choice. The reasons for this include air traffic control agreements, the distribution of airspace, and the provision of efficient and safer flight paths.