Unlike some of its closest allies, Canada has never operated airborne early warning and control (AEW&C) aircraft. That is set to change. Following a recent announcement by Prime Minister Mark Carney, Canada has entered into negotiations with Saab to acquire the GlobalEye early-warning system built on the Canadian-made Bombardier Global 6500.

AEW&C platforms combine detection, tracking, and coordination into a single airborne node. Operating at altitude, their radars can see farther and track targets that attempt to use terrain or clutter to evade detection. Just as importantly, they bring together sensing and decision-making in real time, allowing crews to direct fighters, manage airspace, and coordinate responses as situations unfold.

None of this capability is new. AEW&C has been central to major air forces for decades. Yet, Canada has never pursued it independently in the past and is moving to acquire AEW&C just as the United States is exploring whether it can move beyond it. The United States has spent the past several years exploring whether AEW&C aircraft can be largely or even entirely replaced by space-based systems. That effort progressed far enough that, in 2025, the U.S. Department of Defense moved to cancel its planned fleet of E-7 Wedgetail aircraft—Boeing’s next generation of AEW&C platforms—choosing to acquire only a small number after Congressional intervention, while still shifting significant resources toward orbital alternatives.

This juxtaposition makes Canada’s decision appear ill-timed. Why, after years of not acquiring its own AEW&C aircraft, is Canada choosing to invest in this capability for decades to come, even as its closest neighbour pursues an alternative?

The answer is not that Canada is out of step. It is that the two countries are solving different problems from different starting points—and in doing so, they are exposing the real limits of space-based surveillance.

Canada’s historical lack of independent AEW&C is not an oversight so much as a reflection of geography, alliance structure, and the threats it was facing.

For decades, Canadian and American air defence has been organized around the joint North American Aerospace Defense Command (NORAD). The main concern for NORAD through most of its history has been to detect, and provide time to respond, to large-scale attacks—especially from the Soviet Union and, later, the Russian Federation. Threats would have limited intrusion routes due to technical limitations, and be forced to use predictable routes in predictable ways.

In that context, fixed, ground-based radar networks provided the most efficient solution. Persistent coverage mattered more than flexibility, and it could be achieved far more cheaply from the ground than from the air. AEW&C was useful, but not essential for Canada, especially given its limited focus on expeditionary operations.

The United States, by contrast, invested heavily in AEW&C because it needed the capability abroad. Airborne early warning allowed it to project power with situational awareness wherever it deployed.

This strategic environment is now changing. Long-range cruise missiles, more capable adversary air forces, and the potential for complex, multi-axis attacks strain systems built around fixed sensors and predictable warning timelines. Emerging tactics such as drones launched from within national borders—see Ukraine’s operation Spiderweb against Russian airbases—mean that detection tools can’t exist only at frontiers. This is particularly true around high-profile targets. At least one mobile radar site was set up in Canada to provide better security during the World Cup and American AEW&C aircraft are almost certainly part of contingency plans.

AEW&C aircraft can also “fill in” when a fixed radar site is down for maintenance, or add an unpredictable node to an area’s radar coverage—an adversary with knowledge of our systems will be confident where they can and cannot operate without detection by fixed sites, while just the possibility that an AEW&C aircraft may unexpectedly show up in an area is something that might deter certain forms of intrusion.

With the United States both shrinking its own AEW&C fleet, and signalling a draft away from close cooperation with Canada—they have placed at least two long-standing cooperation forums, the Permanent Joint Board on Defence and the Army Reserve General Officers Advisory Board, on hiatus so far in 2026—it makes sense for Canada to fill this gap with an independent capability.

The United States is not filling a gap—it is attempting to evolve an already mature capability.

For decades, American airpower has relied on large AEW&C fleets, including the Air Force’s E-3 Sentry and the Navy’s E-2 Hawkeye. These platforms remain effective, and their successors are highly capable. The shift away from them is not driven by dissatisfaction—except perhaps by the sense that they’re increasingly vulnerable—but by the appeal of what space-based systems might offer.

In theory, satellites could provide persistent, global coverage without the constraints of aircraft. They do not require refuelling, are less exposed to immediate threats, and can operate continuously. Their data can be fed to ground-based analysts who can be rotated without affecting the platform.

A sufficiently large constellation could create an “always-on” surveillance network—something no fleet of aircraft can match. This vision is driving U.S. investment.

The challenge for other countries is that the physics and operational realities of space impose constraints that must be overcome. And the solutions to those constraints require enormous scale.

A typical AEW&C aircraft might detect targets at ranges of up to 500 km. A satellite at 300 km altitude, using a comparable radar, would have an effective footprint at the Earth’s surface of approximately 400 km in radius. That satellite would be moving at roughly 8 km per second, meaning it could only observe a given location for about 100 seconds before passing overhead.

Maintaining continuous coverage would require a succession of satellites passing over the same area. A single orbital ring could require dozens of satellites to avoid gaps. Because the Earth rotates beneath those orbits, multiple rings would be needed to maintain persistent coverage across the globe.

Even under optimistic assumptions, this implies constellations numbering in the thousands. In practice, inefficiencies, overlap, and coverage gaps would push that number higher. Operating at higher altitudes, with more power, to increase each satellites operating footprint quickly becomes impossible due to the radar power equation, which demonstrates that increasing the distance to a target by 2x increases the power needed to detect it by 16x.

Even at lower altitudes, power is a major constraint. Solar power is the only economical option for a satellite network of this scale, but the practical limitation on the size of solar collectors and the nature of orbits which pass into darkness will prevent full-power operations at all times. A pair of satellites, with one receiving and one transmitting at any time, will both reduce power requirements by limiting self-interference and allow the two satellites to swap between high-power transmitting and low-power receiving tasks. If that’s insufficient, there’s no inherent reason why constellations of 4, 6, or more satellites can’t fly together and operate cyclically. The cost of this would increase, but still likely be lower than replacing each satellite’s solar systems with a nuclear generator. This would have the side-benefit of creating redundancy in case one satellite fails due to malfunction or hostile intervention.

Taken together, these factors suggest that a truly persistent, space-based alternative to AEW&C could require constellations numbering in the thousands, if not tens of thousands.

Canada is a world-leader in the use of space technologies. Sources vary somewhat by methodology, but Canada is routinely included among the top 10 nations in terms of satellites controlled either by its government or entities within the country—sometimes within the top 5. However, the total number is probably best measured in the dozens, and is certainly less than 200. 10,000 satellites is a very different scale.

This is where the United States differs fundamentally from Canada.

The only entity in the world to have launched more than 10,000 satellites is US-based SpaceX, which has recently eclipsed that figure as part of its Starlink service. It is, therefore, not surprising that a major early-stage contract for the US Department of Defense’s Space-Based Moving Target Indicator—a satellite based radar system—was awarded to SpaceX in recent weeks. However, the list of countries that can contemplate a system of this scale today is still extremely short, and perhaps only includes one country.

For the United States, the question is not whether such constellations can be built, but whether they can deliver the required performance at an acceptable cost. Today the United States is still hedging its bets by purchasing some AEW&C aircraft, setting up a production run that could be extended if space technology falls short of hopes, or takes longer to establish than is expected. Those aircraft may also find use in niche cases that satellite systems aren’t equipped for. But the calculation they’re doing is one of managing a transition.

That is a fundamentally different calculation than the one Canada faces.

Canada is not in a position to build or sustain a space-based alternative to AEW&C aircraft at anything approaching the scale required for persistent coverage. Even if it were, doing so would entail enormous cost, technical risk, and long timelines that would force enormous sacrifices elsewhere.

More importantly, Canada’s immediate requirement is not global persistence. It is a flexible, deployable capability in specific regions—particularly in the defence of North America—that replaces the capability the United States is divesting or which may become unreliable.

AEW&C aircraft are well suited to that role. They can be deployed where needed, integrated with allied forces, and adapted to a range of scenarios. They provide immediate capability rather than a long-term technological bet.

There are also alliance considerations. Many U.S. allies rely on AEW&C and face the need to replace aging fleets. If the United States reduces its commitment to this capability, others will look for alternatives. By moving early, Canada can position itself within that ecosystem, particularly given the domestic industrial role in the GlobalEye platform.

From this perspective, Canada’s decision is pragmatic. It addresses a clear operational need with a proven solution, while supporting domestic industry and aligning with allied requirements.

The apparent divergence between Canada and the United States is, in reality, less stark than it appears.

The United States will, under any circumstance, continue to operate some number of AEW&C aircraft for decades to come. Conversely, Canada’s acquisition of AEW&C does not preclude greater use of space-based capabilities in the future. In fact, Canada has a number of on-going projects doing just that—just not on the scale of multiple-thousands of satellites.

The future of early warning and control is likely to be hybrid for at least decades to come—combining space-based sensors, airborne platforms, and ground-based systems into an integrated network. What differs is how that balance will be struck, with Canada leaning more heavily on aircraft while the United States hopes to lean in the other direction.

Canada’s move into AEW&C is not a case of adopting a fading technology just as its useful life comes to an end. It is the adoption of a capability that remains highly relevant, precisely because its alternatives are not yet mature enough to replace it.

The United States is experimenting at the frontier, leveraging its scale and resources to explore what comes next. Canada is addressing a more immediate need with a proven tool.

Both approaches are rational. Both reflect different constraints, priorities, and risk tolerances. The core question any country should ask when acquiring a new capability is whether it solves the problem that needs solving in the most beneficial way.

For Canada, AEW&C clearly does.