Why Might The World's Most Anticipated Commercial Aircraft Have Boeing Worried?
The Lockheed C-5 Galaxy and the Boeing C-17 Globemaster III are two of the most iconic military transport aircraft in aviation history. Towering over most runways, both are designed to move immense amounts of cargo, ranging from main battle tanks to entire helicopter units, across continents and into challenging environments. Each aircraft embodies a different design philosophy: one built for maximum strategic lift during the Cold War, and the other engineered for flexibility and efficiency in modern global operations.
This article will explore that comparison in detail. We'll look at the raw dimensions of each aircraft, examine their payloads and range, and consider the roles they were designed to fulfill. Beyond just the numbers, we'll also evaluate how the two planes are used in practice, and what military planners, pilots, and aviation analysts have said about their effectiveness. By the end, you'll know not only which aircraft is technically larger, but also how size interacts with capability and versatility.
C-5 Galaxy Vs. C-17 Globemaster III: The Short Answer
In terms of raw physical size, the Lockheed C-5 Galaxy is unquestionably larger than the Boeing C-17 Globemaster III. The Galaxy is longer, has a broader wingspan, and possesses a significantly heavier maximum takeoff weight. The C-17 was deliberately designed with different priorities: tactical flexibility, shorter runway performance, and modern efficiency. As a result, although the Galaxy holds the title of being the larger aircraft, the Globemaster often proves more practical in everyday operations.
The C-5 Galaxy was developed by Lockheed (today Lockheed Martin ) in the 1960s at the height of the Cold War. First flown in 1968, it was conceived as a strategic airlifter capable of transporting outsized cargo, including battle tanks, helicopters, and even intercontinental ballistic missile components, across oceans. At 247 feet (75.3 meters) in length and with a 222-foot (67.9-meter) wingspan, it remains one of the largest aircraft ever built.
By contrast, the C-17 was originally designed by McDonnell Douglas (later acquired by Boeing in 1997) and entered service in the 1990s. At 174 feet (53 meters) long with a 169-foot (51.7-meter) wingspan, it is much smaller, but it was engineered to excel in areas where the C-5 could not. Most notably, the Globemaster can land on short, austere runways as little as 3,500 feet long, making it ideal for tactical deployments and humanitarian relief where infrastructure may be damaged or nonexistent.
In terms of service, both aircraft remain pillars of global airlift. The Lockheed C-5M Super Galaxy fleet is exclusively operated by the United States Air Force , with around 52 aircraft in service today following upgrades from older C-5A/B/C variants. Its niche role is hauling the heaviest and largest cargo that no other U.S. aircraft can carry. The Boeing C-17 Globemaster III, on the other hand, has seen much wider adoption .
Over 275 examples were built, with more than 220 active in the USAF and additional aircraft serving with allies including the United Kingdom, Australia, Canada, India, Kuwait, Qatar, the United Arab Emirates, and NATO's Heavy Airlift Wing. This broad international presence underlines the C-17's practicality and versatility in global missions ranging from combat resupply to humanitarian disaster relief.
Size, Payload, And Range: Breaking Down The Numbers
When comparing the C-5 Galaxy and the C-17 Globemaster, "size" isn't just about physical dimensions. It also includes how much each aircraft can carry, how far it can fly with that load, and where it can operate. The C-5 was designed as a pure strategic lifter, focused on hauling the heaviest and most oversized cargo across oceans. The C-17, while smaller, was built with flexibility in mind, able to carry substantial loads but also operate from short or rough runways that the C-5 could never use. In essence, one represents raw capacity, while the other emphasizes adaptability.
Specification
Lockheed C-5 Galaxy
Boeing C-17 Globemaster III
Length
247 feet (75.3 m)
174 feet (53 m)
Wingspan
222 feet (67.9 m)
169 feet (51.7 m)
Maximum Takeoff Weight
840,000 lbs (381,000 kg)
585,000 lbs (265,000 kg)
Payload
281,000 lbs (127,460 kg)
170,900 lbs (77,500 kg)
Range (with payload)
~5,500 nm (10,186 km)
~2,400 nm (4,444.8 km)
Runway Requirement
Long, reinforced
3,500 feet, austere strips
During several conflicts and natural disasters, the C-17 was often used to deliver supplies directly to forward operating bases with minimal infrastructure, or even MEDEVAC. According to Capt. Benjamin Allen, 43rd Aeromedical Evacuation Squadron .
"The sheer versatility of the C-17 aircraft is amazing. One moment the cargo area is filled with equipment, the next it's filled with wounded warriors for transport to higher echelons of care. I'm honored to fly on an aircraft that has the capability to support such a multitude of capabilities".
The C-5, in contrast, flew strategic missions between major bases where its size could be accommodated. Each aircraft excels in its domain, but the numbers make it clear: in raw size, the Galaxy wins.
A Cold War Giant And A Modern Workhorse
Instead of thinking of the C-5 and C-17 as competitors, it's better to see them as products of two different eras and requirements. The C-5 was built to support a Cold War-era strategy: moving enormous amounts of hardware across oceans to reinforce distant theaters of war. Size and range were paramount, even if that meant fewer options for where it could operate.
The C-17, however, represents the post-Cold War shift toward rapid response. Rather than focusing purely on maximum load, its design emphasized versatility, able to perform strategic lift when needed, but also agile enough to land in remote areas, support peacekeeping missions, and deliver aid during humanitarian crises. One key example of this difference is loading configuration:
The C-5 uses front-and-rear cargo doors, enabling drive-through loading for massive equipment The C-17, while smaller, is optimized for faster loading/unloading cycles and features advanced systems for handling mixed cargo, from vehicles to paratroopers.
The US Air Force has operated both aircraft side by side for decades, optimizing their deployment in operational theaters. While the C-5 can haul more in a single trip, up to 281,000 pounds, the C-17's ability to reach remote or improvised airstrips means it often carries the load in day-to-day missions. This reflects a broader strategic evolution: from Cold War-era logistics focused on bulk strategic lift, to today's emphasis on agile, flexible global mobility in both conflict zones and humanitarian crises.
Together, these aircraft demonstrate how military transport design evolved: from "biggest possible" to "most adaptable possible." Today, both remain indispensable to the US Air Force, complementing each other's strengths and ensuring that United States and its allies can project power, deliver aid, and respond to crises anywhere in the world.
How They Compare To Other Military Airlifters
To put the C-5 Galaxy and C-17 Globemaster III into perspective, it's useful to compare them with other large military and specialized cargo aircraft. The Antonov An-124 Ruslan and the Antonov An-225 Mriya are two of the most famous examples, designed specifically for outsized cargo and extreme payloads. The An-225, at 275 feet long with a wingspan of 290 feet, surpassed the C-5 in nearly every dimension and held the record for the heaviest aircraft ever built. The An-124, slightly smaller at 226 feet long with a 240-foot wingspan, remains widely used for strategic airlift in both military and civilian specialized missions.
Other modern military airlifters, such as the Lockheed Martin C-130J Super Hercules, Kawasaki C-2, and Airbus A400M Atlas, serve complementary roles. They are smaller than the C-17 and C-5 but excel in tactical flexibility, short-field operations, and regional transport, similar in philosophy to the C-17 but on a smaller scale.
Aircraft
Length, feet (m)
Wingspan, feet (m)
Max Payload, lbs (kg)
Primary Role
Antonov An-225 Mriya
275 (83.8)
290 (88.4)
551,000 (250,000)
Oversized cargo, strategic lift
Antonov An-124 Ruslan
226 (69)
240 (73.3)
330,000 (150,000)
Strategic/oversized cargo
Lockheed C-5 Galaxy
247 (75.3)
222 (67.7)
281,000 (127,460)
Strategic cargo, outsized transport
Boeing C-17 Globemaster III
174 (53)
169 (51.5)
170,900 (77,500)
Tactical & strategic cargo
Lockheed Martin C-130J Super Hercules
97 (29.6)
132 (40.2)
42,000 (19,050)
Tactical airlift, short-field ops
Kawasaki C-2
174 (53)
165 (50.3)
88,000 (40,000)
Tactical/strategic airlift
Airbus A400M Atlas
143 (43.8)
148 (45.1)
81,600
(37,000)
Tactical & strategic transport
Embraer C-390 Millennium
115 (35.2)
115 (35.1)
57,300 (26,000)
Tactical transport, flexible lift
This comparison highlights the spectrum of strategic and tactical military airlifters. The C-5 Galaxy sits near the top in terms of sheer size and payload, but it is outclassed by the specialized Antonov aircraft when it comes to maximum capacity. The C-17, while smaller, remains one of the most versatile airlifters in the world, capable of bridging the gap between strategic and tactical operations.
The broader takeaway is that in modern military aviation, size alone does not define effectiveness. The C-5 dominates in strategic lift, the Antonovs specialize in extreme oversized cargo, and the C-17 balances capacity with operational flexibility. This diversity allows military planners to choose the optimal aircraft for each mission, rather than relying on a single "largest" solution.
When Bigger Isn't Always Better
While the Lockheed C-5 Galaxy offers unmatched strategic lift, its immense size comes with notable trade-offs. The Galaxy's sheer scale results in higher maintenance costs, longer turnaround times, and the need for long, reinforced runways. Not every airbase worldwide can accommodate its 247-foot length and 840,000-pound maximum takeoff weight, which limits its deployment options in certain theaters or urgent operations.
In practical terms, this makes the C-5 less suited for rapid-response or contingency missions in austere environments. During humanitarian relief or military operations in remote regions, the Boeing C-17 Globemaster III has proven far more flexible. It can land on short, unprepared runways as little as 3,500 feet long, or even on dirt and gravel strips, delivering vital supplies directly where they are needed. The Galaxy, by contrast, must often rely on larger, established bases, requiring additional logistics to move cargo forward. That said, when it comes to carrying truly outsized loads, the C-5 has no equal among active Western aircraft.
Ultimately, "bigger" does not always mean "better." Mission context dictates which aircraft is most appropriate. The C-5 excels at intercontinental, outsized cargo lift; the C-17 strikes a balance between payload and tactical access; and smaller transports such as the C-130J Super Hercules or Airbus A400M provide unmatched versatility in constrained or hostile environments. Together, they form a complementary fleet where size, range, and flexibility are carefully balanced to meet global mobility needs.
The Bigger Picture: Why Both Aircraft Still Matter
So, is the C-17 Globemaster bigger than the C-5 Galaxy? The answer is no: the Lockheed C-5 is longer, wider, and capable of carrying more. But that's only part of the story. The Boeing C-17 was built smaller on purpose, prioritizing access and flexibility over sheer size.
The US Air Force's continued reliance on both aircraft shows that they complement rather than replace each other. The Galaxy handles the outsized jobs that nothing else can, while the Globemaster delivers reliability and adaptability on a daily basis.
Looking ahead, the C-17 will likely remain the workhorse for decades, while the C-5 fleet continues to receive upgrades to keep it relevant. Together, they highlight that in aviation, size is only part of the equation; function and flexibility matter just as much.
Boeing Stock Code BA Business Type Planemaker Date Founded July 15, 1916 CEO Kelly Ortberg Headquarters Location Chicago, USA Key Product Lines Boeing 737, Boeing 747, Boeing 757, Boeing 767, Boeing 777, Boeing 787 Expand Collapse