Were faulty IFF protocols to blame for the loss of a Russian IL-20M over the Mediterranean?
Following the downing of a Russian Air Force Ilyushin IL-20M (NATO reporting name Coot) Electronic Intelligence (ELINT) gathering aircraft by a Syrian NPO Almaz S-200 (NATO reporting name SA-5 Gammon) high-altitude Surface-to-Air Missile (SAM) battery on 17 September (analysis here), more details have shed light on the possible cause of the aircraft’s demise.
Fog of War
Sources close to the US intelligence community told MONCh that the loss could be, “one of those ‘fog of war’ issues,” referring to military strategist Carl von Clausewitz who wrote in his seminal 1832 work “Vom Kriege “(On War) that: “War is the realm of uncertainty: three quarters of the factors on which action in war is based are wrapped in a fog of greater or lesser uncertainty.”
The source placed blame for the incident on both the Russian and Syrian militaries, in particular their handling of Identification Friend or Foe (IFF) protocoles.
Put simply, IFF uses radio transponders which transmit when challenged by an IFF interrogator or a civilian Air Traffic Control (ATC) Secondary Surveillance Radar (SSR). The IFF interrogator is usually collocated with a SAM battery’s ground-based air surveillance radar, or an airport’s primary surveillance radar. The transponder transmits a Very/Ultra High Frequency (VHF/UHF; 30 megahertz/MHz to three gigahertz) radio message across containing details of the aircraft’s velocity, altitude and identity.
The problem, the source added, is that there are, “three different IFF systems at work here: An encrypted Russian-wide military IFF system that is not releasable to third parties and hence will not equip the Syrians; the ‘standard’ military IFF system and the civilian International Civil Aviation Organisation (ICAO) mandated transponder (IFF/SIF) that responds to ATC AAR challenges.”
“The flight was over international waters (the Mediterranean ) and the IFF/SIF would have to have been operating by convention. The signal provides identification of the plane, the altitude, and airspeed for ATC.” Military aircraft will transmit IFF information to IFF interrogators collocated with ground-based air surveillance radars: “All shooting ground-based air defence systems perform an IFF interrogation before permitting a SAM or AAA (Anti-Aircraft Artillery) system to fire.”
Problems may have commenced with the S-200’s P-14 (NATO reporting name Tall King) VHF (133-144MHz/216-225MHz) ground-based air surveillance radar potentially being bereft of an IFF interrogator capable of receiving IFF/SIF transmissions. Such transmissions would have identified the IL-20M as friendly.
The source added that traditionally in Soviet and Warsaw Pact doctrine, the separation of civilian and military ATC was, “nearly absolute.” Syria has been a loyal client for Soviet, and later Russian, air defence equipment and it is entirely possible that they also purchased such doctrine off-the-shelf. The IL-20M may have been squawking that it was friendly using its IFF/SIF transponder, but the S-200 battery had no way of receiving these transmissions. For all intents and purposes, the IL-20M could have appeared as nothing more than an unidentified track on the S-200 radar operators’ screens. The only military IFF transmissions the IL-20M may have made was on the Russian encrypted IFF system to which the Syrians are not thought to have been given access: The aircraft may have been showing the Russians that it was friendly, but not the Syrians.
The source continued that the Syrians may have detected the four Israeli Air Force (IAF) F-16Is performing an air-to-surface missile attack against targets in Syria ’s Latakia province on the Mediterranean coast. Reports stated that as the IL-20M was making its approach to Hmeimim airbase in northeast Syria which houses a sizeable number of Russian combat aircraft, it was hit by a SAM around 19 nautical miles (35km) off the coast, and that this occurred when the F-16Is were in the same section of airspace.
The Syrian air defenders could have been confronted with five aircraft, none of which were making any IFF transmissions on frequencies that the P-14 could receive. They therefore assumed all the aircraft were hostile and engaged them. The F-16Is may have been able to avoid destruction through rapid manoeuvring and using their own self-protection systems, but the IL-20M was not so lucky: “They would have engaged the targets, and a blip is a blip. The Il-20M could have been the closest target to the S-200 battery, and probably the closest to Syria . And boom,” the source said.
That said, Israeli reports stated that the IL-20M was not in the vicinity of the F-16Is when the latter were performing their attacks, and that the F-16Is were safely back in Israel when the destruction of the IL-20M occurred.
This leaves a second possibility: If the F-16Is were indeed out of the area, was the attack a case of mistaken identity?
Israeli sources revealed to MONCh that air strikes in Syria have often been accompanied by IAF Gulfstream G-550 converted business jets equipped with the Israel Aerospace Industries’ (IAI) EL/W-2085 S-band (2.3-2.5GHz/2.7-3.7GHz) and L-band (1.215-1.4GHz) airborne surveillance radar, or IAI’s EL/I-3001 Signals Intelligence (SIGINT) gathering system.
These aircraft are used to coordinate the air strike, and collect SIGINT regarding Syrian air defences, and to jam radars if necessary to help protect the strike package. The G-550s are thought fly orbits some distance from the strike package to reduce their chances of being hit by SAMs.
Did Syrian air defenders mistake the IL-20M for one of these Israeli aircraft loitering in the Mediterranean after the attack had taken place to collect post-strike SIGINT?
There is still much we do not know, and are maybe unlikely to know, regarding what was obviously a serious error by Syrian air defence. As the US source emphasised, what Russia seems to be saying to Israel is: “I’m not saying it was your fault; I’m saying I’m blaming you.”