
Patriot Missiles Are Made in America and Fail Everywhere - vilhelm_s
http://foreignpolicy.com/2018/03/28/patriot-missiles-are-made-in-america-and-fail-everywhere/
======
seldonnn
This is the pac-2 missile which was fielded in 1990 and not designed to combat
these kinds of missiles.

PAC-3 is much more advanced and the kill vehicle much more accurate.

~~~
thomasz
"In fairness, the system deployed in Saudi Arabia — the Patriot Advanced
Capability-2 or PAC-2 — is not well designed to intercept the Burkan-2
missiles that the Houthis are firing at Riyadh. The Burkan-2 flies around 600
miles and appears to have a warhead that separates from the missile itself."

Seriously? The system can't intercept threads it wasn't designed to? That's
the article?

~~~
Jtsummers
It wasn't designed to, but the system keeps being deployed to defend against
these threats. Leads to a question: What's the point of continuing to deploy
something that, by all (unclassified) accounts, seems to have no real utility?

~~~
pm90
That's how procurement, and especially military procurement, works in most
countries which have some degree of corruption. Or at least: when there isn't
any good oversight by the stakeholders. Seems like the procurement of Patriot
missiles was driven more by a need to "buy from the USA" than as an actual
credible way to thwart actual threats. Which is incredibly surprising EVEN
after knowing how this works because presumably the Houthis are using
Iranian/Iran-derivatives of missile systems and Iran is supposed to be the
primary geo-political rival to the Sauds. (Makes me wonder what else won't
really work in an actual war).

Let me say that I'm a pacifist 100%; diplomacy comes first and all that but
war is really where you can't lie and all your bad decisions are right there
in your face and fuck you up completely if you didn't think hard enough
through these things. This particular incident reminds me of when the
Pakistanis procured the latest F-6 aircrafts from the US but were unable to
use them effectively in a war against India (1971) because their pilots were
not sufficiently trained in how to handle the advanced aircraft systems....
oops.

~~~
Jtsummers
Sadly a very accurate statement. US allies are encouraged and sometimes
required to buy US weapon systems even if they have no real utility, need, or
capability to use them. Often they purchase them directly from the US
government (versus the manufacturer), this is one way the US government
directly makes money, provides a form of corporate welfare (for the defense
industry), and subsidizes its weapon system development.

~~~
Covzire
I'm not seeing a problem here, assuming the hardware sold works as intended of
course.

~~~
Jtsummers
> even if they have no real utility, need, or capability to use them.

This is the critical part. The hardware may work as intended, but if no one
can operate it what use is it? If it works as intended but is ineffective
against the enemies weapons or techniques what use is it? Or if there isn't
even an enemy to use these systems against? But to play ball with the US as an
ally, nations can be placed in a position where they're making these purchases
whether appropriate or not.

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dikkechill
The mentioned 1991 issues with the Patriot Missile were due to an issue
converting integers to floats.

    
    
      The [system's] prediction of where the Scud will next appear is a function of the Scud's known velocity and the time of the last radar detection. 
      Velocity is a real number that can be expressed as a whole number and a decimal (e.g., 3750.2563 . . . miles per hour).    
      Time is kept continuously by the system's internal clock in tenths of seconds but is expressed as an integer or whole number (e.g., 32, 33, 34 . . .). 
      The longer the system has been running, the larger the number representing time. 
      To predict where the Scud will next appear, both time and velocity must be expressed as real numbers. 
      Because of the way the Patriot computer performs its calculations and the fact that its registers are only 24 bits long, the conversion of time from an integer to a real number cannot be any more precise than 24 bits. 
      This conversion results in a loss of precision causing a less accurate time calculation. 
      The effect of this inaccuracy on the [system's] calculation is directly proportional to the target's velocity and the length that the system has been running. 
      Consequently, performing the conversion after the Patriot computer system has been running continuously for extended periods causes the [system's estimated Scud position] to shift away from the center of the target, making it less likely that the target will be successfully intercepted.   
    

See also
[http://cs.furman.edu/digitaldomain/themes/risks/risks_numeri...](http://cs.furman.edu/digitaldomain/themes/risks/risks_numeric.htm)

~~~
vilhelm_s
There was just a single failure due to the arithmetic bug (and they patched
the software the day after it happened). The general bad performance of
Patriot missiles in the gulf war was because shooting down ballistic missiles
is hard, not because of a discrete bug.

Incidentally, although this is often described as a "floating point bug", the
actual arithmetic was 24-bit fixed point. In order to convert from tenths of
seconds to seconds they multiplied by 1/10 = 0.00011001100110011001100. If
they had used a floating point format with a 24-bit mantissa, they could have
multiplied by 2^-3 * 0.110011001100110011001100, giving 4 more bits of
precision, which would probably have been enough to intercept the missile! :)

Also perhaps interestingly, the problem only arose because a software upgrade
had introduced a new function to do the conversion more accurately, but didn't
call it everywhere. If they had used the old inaccurate conversion throughout,
the errors would mostly have cancelled out.

See [http://www-users.math.umn.edu/~arnold/disasters/patriot.html](http://www-
users.math.umn.edu/~arnold/disasters/patriot.html)

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dogma1138
Patriot missiles did more damage than Iraqi SCUDs fired at Israel (they are
technically responsible for the only Israeli casualty in the war) in 1991
which is why right after Israel went on full steam with the development the
Arrow.

US missile defense was always a mess.

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ummm32
Just wanted to say, for sure there's wrong stuff everywhere (a couple of
versions of failed missiles maybe), somewhere in the system, but America is by
far one of the best countries in the world to have been born, and I'm not
being a crazy fan or something, just stating the facts. I think many people in
there just like to critizice a little too much about everything, not usually
from objectivity (not knowing how actually difficult is to keep things going
ok). Many would like to have half a country like the one you have there. Just
saying.

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rossdavidh
Theory: it's a bluff. You want to at least convince the enemy that their
missiles are getting shot down. Trying to mislead the enemy via newsmedia is
at least a century old (in some ways much older).

Problem: social media, and a very fragmented internet newsmedia sector, make
this less effective than before. The Houthis no doubt are aware that the
Saudis are not successful.

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mikhailfranco
Maybe it's only good at friendly fire?
[http://news.bbc.co.uk/2/hi/uk/2877349.stm](http://news.bbc.co.uk/2/hi/uk/2877349.stm)

 _Patriot: killing allies in the skies and civilians on the ground since
1990._

~~~
mikhailfranco
Son et Lumière - full of sound and fury, signifying nothing

[http://www.moonofalabama.org/2018/03/two-failures-in-one-
day...](http://www.moonofalabama.org/2018/03/two-failures-in-one-day-missile-
defense-is-an-embaressment-it-wont-work.html)

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exabrial
PAC2 is downright dangerous to the people firing the missiles! From failing to
intercept, exploding too late, software bugs, the whole system is an
engineering joke.

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Invictus0
I don't know anything about this issue but am interested in learning more. Has
anyone read any other reports like this about the Patriot system?

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mtgx
Fortunately, there's a sucker born every day:

[https://www.reuters.com/article/us-raytheon-poland-
patriot/p...](https://www.reuters.com/article/us-raytheon-poland-
patriot/poland-signs-4-75-billion-deal-for-u-s-patriot-missile-system-facing-
russia-idUSKBN1H417S)

~~~
yread
FWIW Poland is getting the PAC-3 Missile Segment Enhancement (MSE), a newer
variant that entered service in 2015

[https://www.bloomberg.com/news/articles/2018-03-28/poland-
si...](https://www.bloomberg.com/news/articles/2018-03-28/poland-
signs-4-75-billion-patriot-missile-deal-with-u-s)

