"Turkish F-16s now able to hit Israeli planes": since when IFF can prevent a fighter from firing a missile?

Sep 19 2011 - 14 Comments

Last week an article titled “Turkey F-16s can now hit Israel targets” made the news and spread quite quickly on the Internet.

According to the article, Turkey has developed a new IFF (Identification Friend or Foe) system for its F-16s that will allow them for the first time to fire at Israeli targets. Developed by Turkey’s Military Electronics Industry (ASELSAN) the new IFF will be mounted on all Turkish fighters (as well as military vessels and submarines) to replace the previous US version which “identified all Israeli targets as a “friend”, thus preventing the Turkish fighter jets from firing at them automatically, even if the Turkish pilots were ordered to fire at them.”

Considered as an ancestor of the RFID, the IFF was developed during World War II to identify friendly targets. Indeed, the acronym is improper, as the system can only identify friendly targets: if an IFF interrogation receives no reply or an invalid one, the target can’t be “declared” hostile.

IFF transponder systems are used by both military and civilian aircraft. Modern IFF have two-channels: one frequency is used for interrogating signals and another for the reply.

The interrogator’s coded signal consists of two pulses spaced at a precisely defined interval. The time interval between the two pulses, discriminated by the onboard transponder circuitry, determines the IFF Mode.

Modes 1, 2, 4 and 5 are used by military planes only whereas mode 3/A, C and S are used by both military and civilian planes. However, some military aircraft (for instance, the F-18E/F Super Hornet) have only Mode 1, 2, 3/A and C modes-capable IFF transponders with Mode 4 available only with specific upgrade fix.

Here’s a quick review of IFF transponders operative modes:

  • Mode 1 provides a mission code (mil only)
  • Mode 2 provides the “tail number” or unit code that identifies a particular aircraft (mil only)
  • Mode 3/A – provides the ATC-assigned identification code for the aircraft (civ/mil)
  • Mode 4 provides a reply to crypto coded challenge (mil only)
  • Mode 5 provides the secured version of Mode S and ADS-B (mil only)
  • Mode C provides the aircraft’s pressure altitude (civ/mil)
  • Mode S provides multiple information formats to a selective interrogation (civ/mil)

Is the IFF linked to the missiles?

As said, the IFF enables quick identification of a friendly aircraft, but it is of little help when trying to identify hostile planes. It is not linked to the aircraft armament and (at least on the majority of the airplanes I know) it can’t prevent an interceptor from shooting at a “friendly” aircraft. This for one a simple reason: you can’t rule out the possibility that some hijacked civil (hence friendly) or military planes are used as weapons of mass destruction to attack a target. Therefore, you can’t rule out the possibility you will need to intercept and shoot down a so-called “renegade” flight with an air-to-air missile, one day.

Furthermore, IFF is automatically switched off when EMCON (Emission Control) is applied, hence, an adversary plane involved in an aggressive mission will likely have its IFF on stand-by….

“As far as I know, the IFF is not interconnected to the missile. The decision to fire and bring down a friendly plane it’s up to the pilot. At least, this is how our planes work” has explained to me an F-16 pilot I’ve inquired on this topic.

If anybody is able to shed some light on the Turkish F-16’s “IFF blockade”, please leave a comment or send me an email.

  • Pierpaolo

    What pilot told you is true for a short range IR seeker missiles, but what about a long range radar guided one?
    When you fire at long distance it could happened that your missile will change target during flight, especially when and if it find a bigger target.
    So it could be that modern BVR missiles have a “safe” mode to avoid them to engage friendly aircrafts.
    Thus is just my thinking, not supported by any facts or proof.

    • Paolo,
      he told me that the IFF has nothing to do with any kind of missile the F-16 can shoot…

  • ray butler

    depending on the iff configuration-which can be complex, a pilot cannot fire at an identified friendly aircraft. you have to study international laws of contract, when altering an aircrafts software, and purchased abilities. be aw
    re that the seller of the product has conditions of sale. nothing is as simple as it appears to be.

    why would turkish planes fire on israeli aircraft in the first place?? another war being planned, cause this is a fairly blatant threat- with little to disguise or distort the intention….
    iff has a purpose, if u remove the module from your flight controls, you can fire at any aircraft.

    • Surely, the possibility to fire to any other plane depends on international laws (and ROE).
      The point is another: the IFF can’t prevent a pilot from shooting to a friendly plane. An interceptor must be capable of shooting at an hijacked civilian plane, “friendly” according to its IFF (provided that it can fire in compliance with the international laws).

  • Can it be that “export version” of american-built fighter are not (or not easily) allowed to fire to “friendly” plane to prevent american built “non USAF” fighters to shoot at USAF planes?

    Just an idea: I have nothing to support it

  • someguywithknowledge

    Modern F-16s have the APX-119 IFF and in most cases, the IFF subsystem is integrated with the situational awareness display. Typically the SA will prevent the operator from exporting a friendly asset to the weapon delivery system.

    • If a fighter plane can’t fire a missile to an aircraft that the IFF considers “friendly” how can it shoot down a hijacked plane?

      • someguywithknowledge

        The restriction in this article is limited to military IFF. Military IFF modes are different than commercial. It requires encryption key(s) that prevent receipt of interrogation and unauthorized friendly replies.

        • I’m not talking about civil planes only. Even military planes can be hijacked. Read what the former pilot of AF1 said about this risk on Sept.11:
          http://bit.ly/pkFHDX

          BTW: Mil IFF and Civ IFF are interoperable in Mode 3/A and C. Encryption comes with Mode 4 but not all tacair planes use it/are equipped with Mode 4A/B.

  • someguywithknowledge

    I believe the problem noted in this article is specific to encrypted military IFF modes. Like others have mentioned, it’s simple to circumvent by turning off IFF or with EMCON. Additionally, an off board sensor can flag the asset as hostile and provide to F-16.

    As far as hijacked military aircraft, the keys would not be loaded in the IFF unit since they’re dumped on power-down. In addition to the aircraft, you’d need to hijack the crytpo loader and the specialist who knows how to load it.

    • As I’ve written in the original article, Israeli aircraft with hostile intentions would fly with IFF switched off.
      Anyway, a friend of mine who flies the F-15E has answered to my question “is the IFF linked to the weapons and able to prevent you shooting at “friendly” aircraft?” in the following way: “No. It’s not linked”.
      I think that his reply says it all.

  • someguywithknowledge

    I understand your point but the article headline implies the old system is ON. “According to the article, Turkey has developed a new IFF (Identification Friend or Foe) system for its F-16s that will allow them for the first time to fire at Israeli targets.” Obviously, if the old IFF system is off, it cannot prevent them from firing at friendly IFF assets. I talked to a guy that works with F-15Es and he agreed there is some integration between the IFF and weapon systems but it is loosely coupled. I think the bottom line is that the original news articles about this topic were based on some truth but embellished to the point of inaccuracy.

  • hakcayurek

    This is related to a Turkish urban myth. Since F-16s first arrived, all the newspapers claimed that Turkish F-16s can not fire on lets say Greeks because they will be recognized as friends. While knowledgable people tried to correct others, the myth kept surfacing again. So you should not expect anyhing serious from that article. It is basically so called defence author of the newspaper doesn’t know what he is writing.

    There is nothing in turkish IFF software that prevents firing on friendly aircraft.

  • iakovos a