Saturday, March 14, 2009

Knocking Down a Drone

U.S. military sources tell Noah Shachtman of the Danger Room that one of our fighters shot down an Iranian drone over Iraq last month.

Details of the incident remain sketchy, and there was no media reporting on the subject prior to Shachtman's account. But the shoot down provides yet another reminder of the "shadow war" fought between the United States and Iran, amid the larger conflict in Iraq.

Since American forces entered Iraqi territory six years ago, Tehran has spared no effort to target our personnel. Operatives from Iran's Qods force have supplied funding and weapons to insurgents, including rockets and explosively formed projectiles (EFPs), used in the deadliest IEDs that destroyed hundreds of military vehicles and killed scores of our troops. In response, U.S. special forces have quietly targeted Iranian operatives, arresting dozens and killing others.

Now, as Mr. Shachtman reports, the shadow conflict has entered another phase, with the recent drone engagement. Iran has long accused U.S. aircraft of illegally entering its airspace, but this is the first time we've acknowledged that Tehran's drones are operating over Iraq, and subject to intercept by our fighters.

The Iranians operate several different types of UAVs, which are used primarily for surveillance. Tehran's most widely deployed drones include the Ababil ("Swallow") which has a wing span of 10 feet and a cruising speed of roughly 160 knots. Iran has also produced a smaller drone, the Mirsad, which has been exported to Hizballah units in Lebanon.

Tehran also claims that it has developed a new, stealthy UAV, with a range of up to 600 miles. But Iran often exaggerates its military capabilities, and reports of the stealth drone have not been confirmed.

But there is little reason to doubt the shoot down story. The Iranians want to keep an eye on American forces in Iraq and with the insurgency in serious decline, Tehran has fewer opportunities for "eyes on the ground." Additionally, platforms like the Ababil can cover more territory--assuming they remain undetected.

By sending UAVs over Iraq, Iran may be trying to exploit perceived weaknesses among U.S. air defenses assets. Patriot batteries left the country years ago, and much of the radar coverage comes from ground-based assets, rather than AWACS. That means our radar "picture" is subject to coverage gaps caused by terrain, ducting and other factors.

Still, we managed to find that Iranian UAV and shoot it down, which is no mean feat. With their small size and slow cruising speeds, drones are notoriously difficult to detect. U.S. SIGINT operators used to watch--and listen--with amusement as Saddam's air defense units tried to track and engage our Predator UAVs. Even with vectoring from ground controllers, Iraqi fighters typically flew past their targets. Once in a great while, the Iraqis managed to knock down a Predator with AAA fire, but we can't recall a single, successful air-to-air intercept, despite dozens of attempts.

Successfully engagement of a drone is (typically) a multi-faceted operation, combining signals intelligence, radar tracking, the right air-to-air weapons and a skilled fighter pilot. We're guessing that SIGINT providing initial cueing and tracking through the intercept/exploitation of radio conversations, and guidance signals unique to the drone. With that information, air or ground-based weapons controllers knew "where to look," and vector the fighter to the right location.

Despite those advantages, a successful intercept was hardly assured. It's likely that both the radar platform and the fighter pilot probably had to adjust the Doppler gates on their radar, to compensate for the UAV's slow speed.

The weapon (most likely) used to down the drone was an IR-guided missile--probably an AIM-9X. Radar tracking issues would make for a difficult AMRAAM shot, and modern fighters carry about 500 rounds of ammunition for their on-board cannon. With burst "limiters," that's enough for no more than 3-4 passes, assuming you can maintain track on the UAV.


Ed Rasimus said...

Might want to update your data on air/air cannon. The venerable M61 Vulcan is pretty much the US standard 20mm. Depending on the installation is is typically less than 1000 rounds. (My F-105 in Vietnam carried 1054. My F-4E a few years later carried about 600.)

At 6000 rounds per minute, that equates to 100 rounds per second. Hardly the 3-4 seconds for a 5000 round load.

In training, strafing at ground targets the load limiter is set for 100 or 150 rounds total expenditure. That can usually get your three to five firing passes.

Mrs. Davis said...

Or it coulda been an A-10.

Unknown said...

Ed--That was a typo. I'm very familiar with the M61 carried on the F-16 and other fighters. Most of the F-16 models I worked with carried just over 500 rounds for the gun. The exception were those that could carry the 30mm centerline pod, part of the abortive effort to make the Viper into a high-speed A-10

Corky Boyd said...

Talking about Saddam trying to knock down our UAVs, there was an in-flight video posted on the internet of head on engagement with an Iraqi fighter. The UAV operator evidently knew he was in trouble, probably from the sources you describe, and launched a hellfire at the fighter. He missed and the Iraqi got the UAV.

My guess, the fighter pilot pooped his pants when he saw what was headed at him.

I can't believe we would waste an AMRAAM on a drone. Maybe it was drone on drone.

lgude said...

I'm thinking of the small UAVs that ground commanders rely on. Having a high tech way to get the other guys drone out of the sky quickly could be decisive. Or are lower tech attacks feasible - like shooting them down with a machine gun or a small heat seeking rocket?

kitanis said...


I am a former enlisted person who spent quite a few years in a mainteance training unit.. Not a Flyer

But my question is.. if it is a UAV under flight control, could a close high speed pass affect the remote flyers ability to control the aircraft in turbulent jet wash?

Just a question.. I would imagine that the sidewinder was used..

pc296 said...
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pc296 said...

The only AAMs F-16's carry in Iraq are wing-mounted AMRAAMs. Also, American military sources have publicly stated that it was an F-16 that got the kill, so it must have either been with an AMRAAM or the M-61. As kitanis pointed out, it would definately be posible for an F-16 to disrubt the flight control with a high speed pass, but such a manuever would involve unnecessary risk since it would involve the possibility of a mid-air collision. Military sources also say that they've recovered the drone wreckage, and it was "in pretty good shape". That being said, I'm guessing it was a gun kill, since an AMRAAM would have blown it to pieces.