“Ski-jump” carriers are smaller and weaker than catapult-equipped ones—but as recent events involving the president show, catapults are far from a silver bullet for effective carrier operations.

Aircraft carriers, as the name suggests, are built to launch aircraft. That mission is central to why the carrier exists, and the method by which it does so is foundational to the carrier.

The two dominant systems used for carrier launches today are STOBAR (Short Take-Off But Arrested Recovery), in which an aircraft launches under its own weight, and CATOBAR (Catapult Assisted Take-Off But Arrested Recovery), under which it is assisted in takeoff by the use of a catapult. Both use arresting wires to recover aircraft. In practice, modern STOBAR carriers use a “ski jump” ramp at one end to aid in takeoff, giving those carriers a visually distinct appearance contrasting with a CATOBAR carrier’s flat deck.

Why Would Anyone Use a STOBAR System Today?

Today, the most advanced aircraft carriers in the world use a CATOBAR setup. This was not always the case; during World War II, some US Navy aircraft carriers lacked catapults, instead relying on the aircraft’s own power for takeoff (and sometimes turning into the wind for assistance).

Since the 1950s, however, catapults have become the baseline for US Navy operations. Until the 2010s, nearly all catapults were steam-powered; the Ford-class carriers have replaced these with electromagnetic catapults (EMALS), although the newer catapults have experienced mechanical difficulties and President Donald Trump has proposed replacing them.

A few points must be made in favor of the STOBAR system. It is a mechanically simpler approach; the carrier provides a short takeoff run ending in a ramp with a 12–14° lift. The fighter accelerates at maximum power and leaves the ramp with an upward flight path, buying a few extra seconds for its wings to generate sufficient lift before it crashes into the ocean. China’s Liaoning and Shandong, Russia’s (now defunct) Admiral Kuznetsov, and India’s Vikramaditya carriers all use STOBAR. There are no complicated catapult systems under this approach, which reduces engineering demands and allows countries without mature catapult technology to still operate conventional carriers.

Still, the absence of a catapult leaves the aircraft dependent only on its engine to provide all of the acceleration required to launch from a ship in a relatively short distance. Because aircraft takeoff performance depends on weight, wind, temperature, runway length, and thrust, a heavily loaded fighter needs more energy to reach flying speed than a lightly loaded one. STOBAR operations therefore impose restrictions on fuel and weapon loads, particularly from shorter launching positions or under unfavorable weather conditions.

The disadvantages of this system are readily apparent. Fighters face trade-offs—either they cannot take as much fuel, which reduces range, or they cannot take heavy weapons, which reduces their effectiveness. They can do less of either in poor weather, although no aircraft carrier is immune from this problem. And while STOBAR systems are mechanically simpler, if a nation is going to the trouble of building an aircraft carrier, it is already spending large amounts of money and investing in technical expertise; why not build the more capable system?

Indeed, many nations that used STOBAR systems to develop proficiency in carrier operations are now transitioning to CATOBAR ones. China’s third aircraft carrier, the Fujian, is catapult-powered, and future PLA Navy vessels will be as well. India’s next carrier, the INS Vishal, is also envisioned as a CATOBAR-equipped vessel, although details on its construction timeline are still unclear and the project may have been halted.

CATOBAR Systems Aren’t Perfect, Either

CATOBAR solves the problems associated with STOBAR by making the ship help accelerate the airplane. Under CATOBAR, the catapult attaches to the aircraft’s nose landing gear and rapidly accelerates the aircraft on the flight deck. So instead of relying exclusively on engine thrust, the fighter receives an enormous external injection of kinetic energy that makes launching aircraft at higher gross weights much more practical. America’s Nimitz– and Ford-class carriers use CATOBAR, as does France’s Charles de Gaulle. 

The CATOBAR system has downsides of its own. Catapults are large, complicated systems; they require substantial power, maintenance, and highly trained personnel.

Broadly speaking, the two types of catapults are steam-powered and electromagnetic, each with their own advantages and disadvantages. 

Steam catapults impose significant demands for steam generation and associated machinery, and generally cannot offer varying strengths of launch. A rugged aircraft like an F/A-18 Super Hornet can take off from the deck of a Nimitz-class carrier without issue, but if an MQ-9 Reaper drone were somehow attached to the catapult, it would be torn apart on the deck if launched from a steam-powered catapult. 

Electromagnetic systems like the US Navy’s EMALS promise greater control of launch forces and compatibility with a broader range of aircraft weights; they can use one amount of force with a small aircraft and another amount with a larger one. They can also change the amount of force mid-launch, starting slow and speeding up until the edge of the flight deck, rather than simply starting at full acceleration as a steam-powered catapult would. But they introduce their own complex electrical and reliability requirements, leading to repeated mechanical breakdowns on the USS Gerald R. Ford (CVN-78), the first vessel of the Ford class. These failures led to a public dressing-down from President Trump earlier this month, who has proposed reintroducing the steam-powered systems on future US Navy vessels from the 2030s onward. 

For nations uninterested in wading into this debate, STOBAR remains an option for smaller navies trying to keep things simple and cheap, and who in many cases lack the heavy aircraft that a CATOBAR system would primarily benefit. And STOBAR can still produce formidable carrier operations, especially for simpler fleet air defense operations.

About the Author: Harrison Kass

Harrison Kass is a writer and attorney focused on national security, technology, and political culture. His work has appeared in Tablet, City Journal, The Hill, The Spectator, and The Cipher Brief. He holds a JD from the University of Oregon and a master’s in Global & Joint Program Studies from NYU. More at harrisonkass.com.

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