
Ask HN: How surface-to-air missile can be fired unintentionally not deliberately - Procedural
https:&#x2F;&#x2F;www.sbs.com.au&#x2F;news&#x2F;footage-of-mid-air-explosion-surfaces-as-canada-australia-say-iran-may-have-unintentionally-shot-plane-down<p>&gt; Canadian leader Justin Trudeau says evidence indicates the strike &quot;may have been unintentional.&quot;<p>&gt; &quot;We have had similar intelligence as our partners have,&quot; Mr Morrison told 2GB radio on Friday. &quot;This is not a deliberate attack ... it&#x27;s a terrible accident.&quot;
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scottdevries
I don’t have first-hand knowledge of how an anti-aircraft system works, but my
theory is that the attack was partly automated. Keep in mind that the plane
was delayed by about an hour on the tarmac, so that may be a factor.

If the plane was cleared for take-off, this would have been coordinated with
the defense forces, who would’ve been prepared for a civilian plane leaving
Tehran. This was probably sent via a take-off window, so the plane being
delayed on the tarmac missed the window.

Keep in mind also that the US had scrambled fighters from the UAE, and so
there was a possibility of intrusion on Iranian airspace. So, a delayed plane
outside of the take-off window may have looked like a radar-dodging fighter to
an automated anti-aircraft system.

~~~
kitsuac
I'm in a similar boat, being rather uneducated here. But I thought it wasn't
completely unusual for countries to prod each other's air space. It seems
really dangerous for Iran to just auto fire at an encroaching aircraft,
potentially starting off a war. In that sense it may be lucky it wasn't a US
fighter.

~~~
antpls
Same boat here. I thought commercial flights had easily recognizable radar
signatures, different from drones, fighters or cruise missiles.

Even for an automatic detection system, this should be easy to detect as "non
immediate threat"

~~~
mytailorisrich
Apparently not so easily recognizable considering that the Russians shot down
a Korean Air flight in 1983, the Americans shot down an Iranian flight in
1988, MH17, and now this.

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hallman76
Possible explanation from a thread[0] on reddit:

> I am wagering an educated guess here that the technical difficulties on the
> plane were transponder related. If the defense missile systems the Iranian
> use were set up with auto interrogation, which is a fairly common thing, and
> the plane had issues with their transponder, which also happens then it is
> possible that the defense system cued the commercial flight as hostile or
> suspect and either launched a missile at the plane (not sure of Irans
> capabilities and limitations with their missile systems in regards to auto-
> fire) or an inexperienced operator with weapon release authority pressed a
> button to shoot a missile at what his system was telling him was a bad guy.

> Missile systems have a series of electronic breaks (think buttons that open
> and close relays allowing the missile firing voltage to reach the igintor)
> and mechanical breaks (think keys that have to be inserted and turned to the
> live/fire position). As the threat level increases the operators automate
> more of the process by closing these breaks. This makes for a faster
> response time to any threat the system identifies.

> So was it possible that an Iranian missile system was set with the minimum
> number of breaks/automated in a way a missile could have been inadvertently
> fired? I would say absolutely this is plausible given the attack a few hours
> prior with an expectation of an American response.

[0]
[https://www.reddit.com/r/worldnews/comments/embvsd/pentagon_...](https://www.reddit.com/r/worldnews/comments/embvsd/pentagon_officials_and_iraqi_intelligence_confirm/fdnpafp?utm_source=share&utm_medium=web2x)

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redis_mlc
You're not going to like this but ...

1) Militaries routinely lock-on to passenger airliners for practise.

Russia is rumored to cancel the missile launch far into the sequence, though
sometimes they goof up and it fires.

2) Airlines knowingly route over war zones to save fuel, and usually only stop
after a shootdown, like the MHA flight over the Ukraine.

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pp19dd
Without going into geopolitics or minimizing any deserved outrage over it and
response to it, there's a reasonable case of thinking this in terms of
consequences of concentrating power. Specifically, consider thinking of this
in terms of accidental discharge rates.

You arm one person in a room and tell them not to shoot, and it's almost a
guarantee they won't. Try this with 10 people and it's still extremely likely
they won't. With 100 it's still a good chance nothing will happen. At 1,000
I'd get nervous. But keep concentrating this force over time and a shooting
becomes a guarantee. Arm 31,000 police officers and wait a year and you'll see
either 23 revolvers or 434 semiautomatics go off accidentally. These are all
seasoned professionals and it still happens to them as a matter of statistical
certainty.

So back to the incident - you can get lost in tracing something like this to
the trigger man, and their immediate firepower locality but the larger
perspective is that risk and danger is directly tied to policy decisions that
created these conditions. Training, aptitude and fire discipline is all over
the charts in any military force and if history tells us anything, it's not a
stretch to call it an accident.

NYPD handgun study including accidental discharges [PDF]:
[https://www.ncjrs.gov/pdffiles1/Digitization/145560NCJRS.pdf](https://www.ncjrs.gov/pdffiles1/Digitization/145560NCJRS.pdf)

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pdx_flyer
It's not impossible for SAM sites to incorrectly set a target. During the Gulf
War an RAF Tornado was shot down by a Patriot missile that had incorrectly
targeted the aircraft. Not long after, a US F-16 pilot reported he was
targeted by a Patriot site as well, but the missile was not launched. In 2003
an F-18 was shot down by a Patriot, killing the pilot.

Most countries have their own IFF (Identify Friend or Foe) codes in their
transponders. Civilian planes also have transponders that identify them as
non-threats, but that is not fail proof (MH17, the 1988 Iranian incident,
etc).

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Monroe13
The best analysis I’ve read is here: [https://www.thedrive.com/the-war-
zone/31791/lets-talk-about-...](https://www.thedrive.com/the-war-
zone/31791/lets-talk-about-how-iran-could-have-shot-down-a-737-full-of-
innocent-people)

Summed up as: older technology, possibly manned by reservists on the final
hours of the graveyard shift, nervously watching a radar screen for a counter
attack from an enemy known to use electronic trickery resulted in a missile
being launched at a misidentified target.

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PaulHoule
It is not hard if you are stressed.

A U.S. Navy ship, the Vincennes shot down an Iranian airliner in 1988 by
accident.

~~~
eloff
My dad was telling me this story last night. I'm surprised I wasn't aware of
it.

In many ways it's a more surprising accident since in those days the U.S. was
not expecting an Iranian attack, but Iran has good reason to be on high alert
and expect US warplanes now.

The US did eventually acknowledge the incident and pay reparations to Iran.
What are the odds Iran does that to Canada now? Approximately zero. I'd be
surprised if they even admit it, even while cornered. A number of Iranians
here in Canada think it was the US that shot down the airliner. Pretty
ridiculous, but if westernized Iranians living in the free world can think
that, imagine what people in Iran would be willing to believe when lied to by
their government.

~~~
AnimalMuppet
The US was _absolutely_ expecting an Iranian attack on the Vincennes. Maybe
not as "probably right now" as Iran was, but it was definitely a realistic,
expected, on-guard-against scenario.

~~~
eloff
Maybe I'm still missing some backstory there of the context in the Gulf in
1988. The Captain of the Vincennes was acting very aggressively on that day,
and shooting down the airliner was the sad end result of that.

~~~
PaulHoule
Iraqis hit the USA Stark with air to sea.missile not long before and there was
extensive low-level surface conflict in the gulf at.That time.

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happytoexplain
It seems obvious to me that the proposition is that the plane was
misidentified or otherwise somehow accidentally targeted instead of some other
target, either by human error or by a not-well-enough-supervised automated
system - not that the _firing_ of the missile was unintentional. I.e. they are
not claiming that somebody accidentally hit the fire button with their elbow,
I think.

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PenguinCoder
Nothing in that says the firing was unintentional. It specifies the TARGET was
accidental.

>US media reported it had been mistakenly shot down by Iran.

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jfalcon
Looking at the video and comparing this to videos of UAV's being shot down
with Stinger shoulder mounted surface to air missiles it looks very close to
identical.

I don't think this was a big missile system like the Patriot or anything.
Airlines have checklists and back-n-forth with air traffic control to set
their transponder and any air traffic control worth anything would be keeping
track of any heavy aircraft leaving their airports which there are reports
that no call of trouble was mentioned by the airliner so that means they've
already reviewed the ATC tapes.

It could have been an abnormally nervous missile platoon in possession of
stingers (or similar) told to be on the alert for air to ground attacks and
maybe something spooked them or they were targeting the airliner like others
have mentioned and someone pulled the trigger unintentionally.

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mytailorisrich
It seems unlikely that they meant to shoot down a civilian airliner right
above Tehran.

It's possible that they were on high alert for fear of an American retaliatory
air strike and misidentified the plane.

It seems reckless to have kept the airspace open and civilian planes flying in
those circumstances, though, because, well...

~~~
ocdtrekkie
I have always been a bit shocked how airliners appear to fly in, around,
above, to, and from combat zones. I suppose people who live in those areas
learn to continue about their lives, but as an American resident, where actual
combat is... pretty uncommon, I can't fathom deciding to get on an airliner
while missile strikes are going on in the vicinity.

~~~
mytailorisrich
In this case they may not have known as it happened during the same night. It
did not happen in the vicinity of the Iranian strikes in Iraq, either: Tehran
is about 900km from Baghdad.

What I'm saying is that if the Iranian authorities were on such high alert for
an air strike on Tehran it might have been wise to close the airspace to
civilian flights instead of letting them continue to fly right in the path of
ground-to-air missile batteries...

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hprotagonist
This is one of the things that concerns me about things like CIWS/Phalanx,
which is a short-range turret gun system for navy vessels.

It has a mode which, when enabled, says "if you show up on my radar and do not
have a friendly beacon on you, you are going to get a kilo of tungsten through
your center of mass and we're not going to bother asking questions of any
human first."

The use case is to prevent another Cole incident, but configuring a weapons
system in such an autonomous mode means that you're in a mode where unintended
deaths are acceptable, and that makes me very, very concerned.

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wheelerwj
i think the general understanding/current story is that it was fired
deliberately, but not at that target.

I guess we'll all find out the official version of the story in the days to
come.

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ocdtrekkie
It's possible the person who fired it thought the airliner was a US military
craft. It's also possible it was intended to be fired at something else, but
targeted the airliner by mistake.

Note that surface-to-air missiles are likely to target heat sources, and it
seems like the engine of the airliner, a significant source of heat, may be
where it was struck.

~~~
antpls
Even if they thought it was an US military aircraft, wouldn't they first try
to make radio contact? Iran and USA are not officially at war, why would they
open fire "at first sight" ?

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zelon88
I'm not convinced. I have a theory that when the US killed Qasem Soleimani
Iran looked over to Russia for a nod of approval. Once they got the nod (yeah,
we'll back you in a proxy war) Iran went ahead with retaliation against the US
and simultaneously put Trump in a position where he will most likely denounce
any responsibility to defend/aid Ukraine. Setting the stage for round 2
Ukrainian invasion.

1\. Russia puts mercs in Crimea to sow unrest.

2\. Russian mercs drive unrest.

3\. Unrest drives Russia to annex (liberate) Crimea.

4\. Obama sanctions Russia.

5\. Russia helps elect Trump.

6\. Trump lifts sanctions against Russia.

7\. Trump endebted to Putin.

8\. Iranian tensions ratchet up.

9\. Trump has a hard on for killing Iran.

10\. Trump has an aversion to confrontation with Russia.

11\. Putin puts Trump in a position to renounce responsibility to defend
Ukraine (world peace).

Putin has set the stage for the US to turn Iran into ISIS: The sequel and
simultaneously weakened Ukraine.

