The exceptional speed and interception abilities of Thaad interceptors create a “canyon effect” echo that can be heard many kilometres away after they strike Iran's missiles.
The UAE's Terminal High Altitude Area Defence (Thaad) system is one of the most advanced in the world, with its unique “hit-to-kill” ability in which an interceptor flying at Mach 8 (9,900kph) can hit an attacking weapon head on.
Thus when a loud boom ripples across the UAE, many assume the source is nearby but in reality it could be more than 100km away.
Supersonic sound
Interceptions often occur at very high altitudes, perhaps than 100km from the Earth's surface, but with the physics of supersonic sound making that distance appear much shorter.
When an object moves faster than the speed of sound, 1,235kph, it creates a shock wave known as a sonic boom, which spreads outward in a conical form.
People underneath the cone of sound will hear a sudden crack, or boom, even if the object of the interception is very high above them.
Soundwaves can also bend back towards the ground, with differences in air temperature and density making distant explosions travel further, generating a powerful boom effect over Abu Dhabi or Dubai.
Some have described it as the “canyoning effect” experienced by troops in mountainous Afghanistan when the Taliban might open fire some distance away but the echoing effect of steep valleys made it sound much closer.
Hit to kill
A US-made system, Thaad has been sold to close allies, with several batteries held by the UAE that have proven of immense value in Iran’s latest attacks, as they did to protect Abu Dhabi against Houthi missiles in January 2022.
The interceptors, which cost $12 million each, are designed when the attacking missile is in its terminal phase, heading downwards at great speed but on a predictable track.
“If your fire control system has calculated the trajectory so the radar has got a track on the missile, then you're more likely to hit it because ballistic missiles in the terminal phase don't tend to manoeuvre,” said Bob Tollast of the Rusi defence think tank. “It's like if you're a fielder in cricket or baseball, you can see the ball coming down and it’s not going to change direction at the last second.”
The incredible ability to hit a missile with a missile – rather than using a shotgun-like spread of shrapnel as in the Patriot system – is the equivalent of “hitting a bullet with a bullet”, he added.
Radar readings
With only 650 interceptors built by Lockheed Martin each year, there is a limited stockpile but they have proven invaluable, particularly in Israel where they have prevented heavy destruction in urban areas.
A key element to the system is its exceptionally powerful AN/TPY-2 radar, with tens of thousands of antenna elements giving operators high precision on a missile's tracking.
It is powered by a one-megawatt generator, the equivalent of energy for 900 homes, giving it time to calculate a precise firing solution for interception.
Countries with Thaad have benefitted immensely from Iran’s previous attacks on Israel, said Mr Tollast. “In those big ballistic missile salvos the radars would have been soaking up a tremendous amount live data on the performance of these Iranian systems. That is gold dust for air defence.”
That will add further security for those in the Gulf while under attack particularly from Iran’s powerful hypersonic missiles such as the Fatah-1.
