Air Defense: May 16, 2003


During the Iraq campaign, only four coalition jets were shot down, But two of them were brought down by American Patriot anti-aircraft missiles. Patriot batteries fired 22 missiles during the war, and the attacks on friendly aircraft appear to have been caused by flaws in the Patriot fire control software. When Patriot radar detects an aircraft, it immediately sends out an electronic signal to the aircraft's IFF (Identify, Friend or Foe) radio. This device is designed to listen for those "interrogation" signals, and immediately respond with a coded signal indicating who the aircraft belongs to. The IFF is used in training, and constantly during the Iraq fighting. So how did the Patriot not recognize the IFF signal, and launch missiles at a British and a U.S. Navy aircraft? Well, it appears that if an aircraft is flying in a certain way (altitude, speed), the Patriot identifies it as a missile, not an aircraft. When the Patriot thinks it has detected missile, it does not waste a few seconds looking for a friendly IFF signal, but promptly fires (if the missile is set on "automatic," which it often is if enemy missiles are expected.) Some types of missiles do go at about the same speed as fast jets, but in retrospect it seems false economy to not send out the IFF interrogation signal unless the radar has spotted a real fast moving (faster than any aircraft) target. If this was indeed the cause of the two friendly fire shoot-downs, changes in the software will no doubt be made. 


Article Archive

Air Defense: Current 2021 2020 2019 2018 2017 2016 2015 2014 2013 2012 2011 2010 2009 2008 2007 2006 2005 2004 2003 2002 2001 1999 



Help Keep Us Soaring

We need your help! Our subscription base has slowly been dwindling. We need your help in reversing that trend. We would like to add 20 new subscribers this month.

Each month we count on your subscriptions or contributions. You can support us in the following ways:

  1. Make sure you spread the word about us. Two ways to do that are to like us on Facebook and follow us on Twitter.
  2. Subscribe to our daily newsletter. We’ll send the news to your email box, and you don’t have to come to the site unless you want to read columns or see photos.
  3. You can contribute to the health of StrategyPage. A contribution is not a donation that you can deduct at tax time, but a form of crowdfunding. We store none of your information when you contribute..
Subscribe   Contribute   Close