Ask HN: How surface-to-air missile can be fired unintentionally not deliberately

15 points by Procedural ↗ HN
https://www.sbs.com.au/news/footage-of-mid-air-explosion-surfaces-as-canada-australia-say-iran-may-have-unintentionally-shot-plane-down

> Canadian leader Justin Trudeau says evidence indicates the strike "may have been unintentional."

> "We have had similar intelligence as our partners have," Mr Morrison told 2GB radio on Friday. "This is not a deliberate attack ... it's a terrible accident."

30 comments

[ 4.1 ms ] story [ 79.7 ms ] thread
It is not hard if you are stressed.

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

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.

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.
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.
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.
> What are the odds Iran does that to Canada now? Approximately zero.

Not now but this will become another bargaining chip and one day they may agree to pay compensation in the context of wider negotiations.

Libya agreed to pay compensations for Lockerbie 20 years later as part of wider negotiations and it is unclear whether they were involved at all...

Exactly, Iran had just launched attacks on several US air force bases in Iraq hours previously and their air defences would have been on high alert for any possible counter-attacks.

In the Vincennes incident the AEGIS tracking software at the time reused tracking IDs for targets, and re-assigned a tracking ID from the airliner to a fighter jet 110 miles away, leading to mistaken information being relayed about the flight's activities.

This goes to show until and unless we know what information the missile system operators had, and what orders they were under, we can't really say what happened and why.

Doesn't the system display aircraft types and friendly / enemy / unknown status?

Something like this -> https://imgur.com/a/kOkRAhd

Friendly aircraft have transponders to identify them. And even without a transponder, certainly a large, slow airliner looks very different on radar than a small, fast fighter or missile.

Seems like the system would require some kind of override to fire at a friendly target.

Stressed, as in, fearful of attack. A surface-to-air missile site (or command and control center) would be one of the first places attacked. That is, the person is under the stress that, if it's a real attack and he doesn't pull the trigger, he may die. (The Vincennes had the same stress.)
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.

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.

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.

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.
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"

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.
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...

Not sure why your being downvoted. A comedian once made a joke after the passenger airline was downed over Ukraine along the lines of "in an airplane you get charged a fee for everything, can't there be a 'avoid active warzones' fee? I'd happily pay that one"

Not commenting on the situation but couldn't airlines avoid tumultuous airspaces in their flight paths?

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.
It costs more in fuel (and travel time) to avoid them... but when a plane gets shot down, that's really expensive.
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...

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.

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" ?
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.
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_...

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.

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.

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

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).

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.

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.