How successful were the Patriot missiles at intercepting SCUDs?

This issue is interesting in its own right but also shows how, in a more general sense, a wide range of answers may be correct depending on the exact definition of the problem.

During the 1st Gulf War Saddam Hussein launched a number of SCUD missiles on the bases of the coalition forces and on Israel (which, incidentally, did not take part in the hostilities). The US Army deployed the anti-ballistic missile system Patriot to negate the threat. The Patriots appeared remarkably successful at intercepting the incoming SCUDs. This prompted the US President George Bush to declare during a visit to the Patriot factory that “Patriot is 41 for 42: 42 Scuds engaged, 41 intercepted!”. However a year later during a House Committee hearing two scientists concluded that according to their independent analysis of video tapes, the Patriot system had a success rate of below 10%, and perhaps even zero. The US Army claimed a success rate of between 40% and 80%. It would be hard to get a wider spread of answers so who was right and who was wrong?


As you may have guessed from my intro, all these claims can be viewed as either correct or incorrect depending on how we define the “success rate”. To kick things off we will assume that a Patriot is “successful” if it hits a SCUD. We also need to clarify that to maximise the chance of intercept up four Patriots were typically launched at each incoming SCUD. Let us now have a closer look at three different scenarios, all apparently quite common during the 1st Gulf War.

In the first event the first Patriot from a salvo of four scores a direct hit. That being the case, the other three Patriots have no target and so cannot be claimed to be “successful”. In the second scenario a SCUD is detected, identified and a salvo of four Patriots launched to intercept it. But before they can, the SCUD breaks up on re-entry into the atmosphere. The resulting debris falls harmlessly in the desert, Patriots self-destruct so no one is hurt. In this case four Patriots were expended but none of them hit the SCUD. And then, finally, we have a SCUD which has not been directly hit but the explosions of Patriot warheads have pushed it off course so it has caused no damage.

The “success” rate in the above three scenarios is, respectively, 25%, 0% and 0%. However, since none of the SCUDs did any damage the definition of “success rate” we used appears meaningless. So, for the sake of comparison, let us now look at how many SCUDs hit their targets in the above three events.  Well – the answer is none which, logically, should correspond to a 100% success rate of the interceptors. So, which answer is correct – 100%, 25% or 0% success rate? Each of them can be correct or incorrect, depending on how we define the problem.

This issue crops up in many areas where complex problems are overly simplified in order to get a news-bite type answer. One example is the Global Warming industry which has invented the derogatory term “climate change denier”. No reasonable person denies that the Earth climate does change – it always has! Most reasonable people accept that in the last 150-200 years the mean global temperature has been generally increasing (with a few plateaus and short-term dips). No one I know about denies that the CO2 and methane levels are rising in the atmosphere and this has some warming effect. Very few people branded as “climate change deniers” actually disagree with any of the above. To quote from the essay by Prof Bob Carter:

In general communication, and in the media, the terms greenhouse and greenhouse hypothesis have come to carry a particular vernacular meaning – almost independently of their scientific derivation. When an opinion poll or a reporter solicits information on what members of the public think about the issue they ask questions such as “do you believe in global warming”, “do you believe in climate change” or “do you believe in the greenhouse effect”. Leaving aside the issue that science is never about belief, all such questions are actually coded ones, being understood by the public to mean “is dangerous global warming being caused by human-related emissions of carbon dioxide”. Needless to say, this is a different, albeit related, question. These and other sloppy ambiguities (“carbon” for “carbon dioxide”, for example) are in daily use in the media, and they lead to great confusion in the public discussion about climate change; they also undermine the value of nearly all opinion poll results.

On the other side of the ledger we have the official scientific “consensus” which, unfortunately, is just as meaningless. What exactly do all the mainstream climate scientists agree on? If they are all like-minded, do we even need so many of them? If they remarkably agree on every single minute aspect of a complex problem like the Earth climate could we not make say half of them redundant, without sacrificing much in terms of science?  We could then use the saved funds to buy gravity lights for half of Sudan!


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