Colonel Turki al-Maliki, a spokesmen for the Saudi-led coalition, revealed during a press conference how the Houthis managed to turn Soviet-made R-27T and R-73E air-to-air missiles into ground-to-air missiles.
The Houthis likely got the R-27T and R-73E missiles from airbases of the Yemeni Air Force, which they captured during 2015. The Yemeni Air Force used to operate these types of air-to-air missiles and others like the R-27R on its Mig-29SMTs.
The R-73E has a range of 30km, while the R-27T has a range of up to 70km. The Houthis likely chose these missiles because the both types are guided by infrared homing, and has the “fire and forget” feature. Other types of air-to-air missiles like the Soviet-made R-27R are guided by semi-active radar homing, which make them harder to turn into ground-to-air missiles, because this type of guidance system requires support from a separate guidance radar detecting the target for the missile.
In order to launch R-27T and R-73E from the ground, the Houthis installed missiles and their launch rails on trucks. The missiles seekers were supplied with electricity from a separate generator because the missiles batteries last for few minutes only.
However, the Houthis don’t add a rocket booster to the missiles to increase their range. Air-to-air missiles lose at least a half of their range when they are launched from the ground because they are originally designed to be launched from warplanes on high altitudes and speeds.
During the 1999 NATO operation in Serbia, the Serbian Army also modified R-60 and R-73 air-to-air missiles to launch them from the ground against NATO warplanes. However, unlike the Houthis the Serbs solved the range problem by adding rocket boosters to the missiles, which acted as a first stage and gave the missiles a longer range even though they were launched from a static armored vehicle.
While the Serbian Army had never shot down any NATO warplane with its modified air-to-air missiles, the Houthis likely managed to shot down a United Sates MQ-9 Reaper unmanned combat aerial vehicle (UCAV) over the Yemeni capital of Saana using their modified air-to-air missiles on October 10.
These modified air to air missiles were also likely used to target an F-16 warplane of the UAE Air Force over the Yemeni capital of Sana’a on June 8, and a F-15 of the Royal Saudi Air Force On May 21. However, both warplanes were not shot down.
The Saudi-led coalition accused Iran of helping the Houthis to modify these air-to air-missiles. However, experts believe that such modification can be made by any well-trained military engineers who worked with these types of missiles before.