Modern surface-to-air missiles give poorer nations the ability to shoot down advanced fighter jets over their territory for a fraction of their cost.
The surface-to-air missile is a ground (or ship) launched missile designed to destroy airborne targets like planes, helicopters, drones, and other missiles. The SAM sounds simple enough—and it is in certain respects. But SAM operations follow a surprisingly complicated process—a launch sequence that moves from detection to detonation in seconds.
How Surface-to-Air Missiles Work
The SAM’s process begins with detection. Long-range surveillance radars, shipborne arrays, airborne early warning platforms, and optical sensors are all capable of tracking a target and offering a track to the SAM’s fire control system. The track consists of range, bearing, velocity, and predicted intercept point. The quality of a specific track dictates whether a SAM system can engage, and which missile will be chosen.
Launch phase: The SAM missile’s launch begins the kinetic portion of its sequence. Short-range MANPADS (like the Stinger missile) are often fired from shoulder tubes or light vehicle canisters, while medium and long-range systems use canister, rail, or vertical launch cells. Propulsion methods vary, with significant implications. Solid-rocket motors dominate the field because they are simple, reliable, and provide a quick boost. But advanced systems use dual-pulse motors or ramjet/ducted-rocket designs to sustain speed and maneuverability over long midcourse flights.
Boost phase: Following the launch of the SAM, it enters the boost phase, which is short but energetic; the motor accelerates the missile to cruise speed, clearing the launch infrastructure. In long-range missiles, the boost is followed by a sustained cruise (ramjet) or a throttle-able solid-rocket profile that conserves fuel for terminal maneuvers. Propulsion profile affects time-to-target and the energy available for last-second turns against evasive aircraft or incoming missiles.
Midcourse guidance systems are varied. Simpler missiles rely on command guidance, which features ground radar tracking both target and missile and sending steering commands. More advanced SAM systems combine inertial navigation with datalink updates, in which ground or airborne radars transmit revised target locations so the missile corrects its course.
Terminal phase: In the final moments of flight—the so-called terminal phase—the SAM relies on terminal homing systems to strike the intended target. Missiles use different terminal homing systems, including semi-active radar homing, in which the ground radar illuminates the target and the missile homes on the reflection; active radar homing, in which an onboard radar seeker actives and locks independently; and infrared seeks, which features passive heat tracking; or dual-mode seekers that mix radar and IR.
To destroy the target, most SAMs carry fragmentation warheads that are triggered by proximity fuzes, detonating near the target to spray high-velocity fragments in a wide cloud—not unlike an aerial grenade. Some modern interceptors even use directional fragmentation, or hit-to-kill designs, for anti-ballistic roles. And in the last moments of flight, terminal maneuvering relies on thrust vectoring or control surfaces.
SAMs Have Fundamentally Changed Air Warfare
The strategic implications of the SAM, and the device’s rather complicated process, is profound. The SAM shapes airspace access, creating denial zones that complicate targeting, and can change the very nature of campaign plans. Crucially, while fighter jets are enormously expensive and pilots require many hours of training, SAMs are somewhat cheaper and can be easily operated. This means that weaker nations without the capacity for a large air force can do much to deny their airspace to enemies at an affordable cost.
The export and proliferation of capable SAM systems have the power to shift regional balances, elevating the risk of escalation and raising the political costs of intervention. And economically, long-range integrated systems are expensive, which incentivizes the development of asymmetric countermeasures, like drones, standoff strike, and cyber/electronic warfare.
About the Author: Harrison Kass
Harrison Kass is a senior defense and national security writer at The National Interest. Kass is an attorney and former political candidate who joined the US Air Force as a pilot trainee before being medically discharged. He focuses on military strategy, aerospace, and global security affairs. He holds a JD from the University of Oregon and a master’s in Global Journalism and International Relations from NYU.
Image: Shutterstock / Petr Bonek.
