Huge Chaff Cloud That Lit Up Radars As It Drifted Across The Midwest Remains A Mystery

Yesterday, meteorologists, and anyone else watching weather radar in southern Illinois, southwestern Indiana, and western Kentucky, noticed an unusual formation drifting through the area. Although evidence remains limited, this was likely a burst of chaff released from a U.S. military aircraft, but there is still no clear explanation as to why the plane released the radar-reflecting countermeasures in this particular area.

At around 3:00 PM Central Time on Dec. 10, 2018, weathermen at local news stations in the area, as well as a National Weather Service (NWS) in Paducah, Kentucky, began tracking the radar “blob” as it dramatically expanded in length and began to move southward. Closer to 2:00 AM Central Time on Dec. 11, 2018, Wayne Hart, the Chief Meteorologist at ABC-affiliate WEHT in Evansville, Indiana, took to Twitter to offer the first real information about the radar reflective plume. 

“Information from a pilot appears to confirm that chaff was the mysterious radar echo that traversed #tristatewx late Monday afternoon/evening,” Hart Tweeted out. “Pilot was told by EVV [Evansville Regional Airport] Air Traffic Control that chaff was released by a military C130 [sic] northwest of Evansville.”

There has been no additional information about what specific service or unit the C-130 might have belonged to or what variant or subvariant it might have been. Hart also did not explain what the purpose of the release might have been beyond telling another Twitter user that it had been related to an unspecified military exercise. We have to stress that this explanation is far from official or corroborated in any tangible way.  

The War Zone has reached out to the Illinois, Indiana, and Kentucky National Guards as well as the U.S. Air Force seeking confirmation and more information. The Illinois Air National Guard’s 182nd Airlift Wing, which does operate C-130s, told us that it only had one aircraft airborne on Dec. 10, 2018, and that it was not carrying chaff at all. At the time of writing, we have not received responses to any of our other queries.

First developed during the Second World War, chaff consists of bundles of radar reflective material, commonly aluminum strips or bundles of metalized glass fibers. These types of material are extremely reflective on radar and as seen in the tracks above, can blind and confuse radars and their operators. The size of the individual strips or strands has a direct impact on what radar bands the chaff affects.

C-130 types do have the ability to fire chaff from their AN/ALE-47 countermeasures dispensing system. The aircraft may have also had a launcher mounted on its rear cargo ramp or fitted in either of the two paratrooper doors on either side of the rear fuselage, that is if a C-130 is responsible for this puzzling countermeasures deployment.

US Navy RR-144, at top, and RR-129 chaff countermeasures, as well as loose chaff, at right. These are similar in basic function to the chaff countermeasures that various C-130 type aircraft use., USN
Countermeasures dispensers on a C-130 type aircraft. The dispensers on the left are loaded with decoy flares that burn in the visual light spectrum, while the ones on the right most likely have infrared flares. Both of these are used to counter heat-seeking missiles. These same dispensers can also hold chaff cartridges if required., USAF

During an actual military operation, fighters jets and other combat aircraft would fire chaff defensively to make it difficult for fire control radars or the seekers on radar-guided air-to-air and surface-to-air missiles to track and engage them. Bulk chaff deployments could help conceal the total number of aircraft involved in a mission or their exact direction of movement. During the invasion of Iraq in 2003, ground- and air-launched modified BQM-34 drones dumped chaff along specific corridors to conceal Tomahawk cruise missiles as they flew toward their targets.

Using chaff during exercises is hardly unheard of and rapidly changing environmental factors, including changes in ambient wind speed and direction, means it can often blow off course. For example, in 2011, chaff appeared on weather radar in northeastern Oregon. In 2013 and again in 2016, similar plumes appeared on radar near the Army’s Redstone Arsenal in Alabama.

The video below shows radar tracks of much smaller trails of chaff during the incident near Redstone Arsenal in 2013.

“Threat countermeasure testing conducted at the U.S. Army Redstone Test Center Wednesday, September 21st, [2016,] resulted in the release of chaff into the atmosphere on the west side of Redstone Arsenal,” the public affairs office at the Army facility said in a statement after that second incident. “While the tests were conducted strictly over the Arsenal and wind speed restrictions were adhered to, climatic factors cannot always be predicted.”

But the chaff in this instance stayed in the area in excess of 10 hours and at its peak stretched along a front more than 50 miles across. The material did not start at a particularly high altitude – approximately 9,000 to 10,000 feet – and the relatively uniform wave drifted from one state into two others in succession, as well. 

This is unusually persistent coverage over a very large area. This could point to a test involving a more exotic type of material that hangs in the air longer. 

“It might be chaff released from an aircraft, but we’ve never seen it quite this hot,” National Weather Service meteorologist Greg Meffert also told the Evansville Courier & Press, referring to how reflective the material was on radar. At that time, WEHT’s Hart had not reported that it was chaff from a C-130.

None of this explains why any U.S. military service would have dropped chaff in this particular location, which isn’t adjacent to any military installation, such as a research or test site. Scott Air Force Base, home to Air Mobility Command’s 375th Air Mobility Wing and the Illinois Air National Guard’s 126th Air Refueling Wing, is 75 miles to the northwest. Neither of those units flies C-130s of any type. 

The U.S. Navy’s Naval Surface Warfare Center Crane Division, or NSWC Crane, is similarly far away, but to the east in neighboring Indiana, and is not typically associated with aircraft research and development programs. To the South, there is the U.S. Army’s Fort Campbell, which is home to various fixed and rotary wing aircraft units, but none of which operate the C-130. It is possible that the Hart misheard the aircraft in question or that his source was confused as to the type. Various types of U.S. military fixed and rotary wing aircraft have countermeasures dispensers that employ chaff.

However, the area where the chaff first begins to appear is within a so-called Military Operations Area (MOA), known as the Red Hills MOA. This is a designated piece of airspace set aside for military aircraft training activities. Red Hills MOA was the site of an F-15C Eagle fighter jet crash during a training mission in 2007 in which the aircraft’s structure gave out and it broke apart around the pilot. 

A map showing the Red Hills MOA. , via

The Red Hills MOA is relatively large, including areas of both Illinois and Indiana. We don’t know if the MOA was active at the time the plume appeared on radar, but it might help explain the incident. 

It is also worth noting that, even within MOAs, the Federal Aviation Administration (FAA) has restrictions on the use of chaff that can impact air traffic and navigational radars because of the obvious hazards to civil and commercial aircraft. But still, that risk is considered somewhat low. A 1998 report on the safety of chaff, which includes evaluations of its impact on people and the environment, from the Government Accountability Office describes the concerns and what had already been done to mitigate the issue:

The report noted that while chaff is effective at confusing enemy radar, it also interferes with air traffic control radar. The report said that chaff had interfered at least twice with Federal Aviation Administration (FAA) radar but added that such events could be effectively avoided or managed. According to the report, safety risks from the use of chaff are extremely low and impacts on aircrews, aircraft, or the public are not anticipated. For example, the report found (1) no incidents of chaff interfering with satellite tracking; (2) two recorded incidents of military fighter aircraft interfering with FAA radar, but details were unavailable; (3) no documentation that chaff had caused aircraft radar systems to falsely identify nearby traffic; (4) no evidence of an aircraft engine failing after ingesting chaff; and (5) no reported accidents in which pilots were distracted by chaff.

The report states that the primary safety concern is the potential for interference with FAA’s air traffic control radar but notes that DOD and FAA have agreed to restrict locations, altitudes, and times at which chaff can be used. The report states that a newer type of chaff that does not interfere with FAA radar is readily available.

At this time, that is what we have to report. The incident is odd because it should be readily explainable on an official level. It very well could have been a C-130, but why was it punching out chaff at a relatively low altitude over that seemingly odd location on a Monday afternoon. And what type of chaff was able to stay airborne and in a relatively cohesive formation for nearly half a day after being released at 10,000 feet? 

Hopefully, we will find out this and more in the coming hours and days. We will keep you up to date as we continue to investigate. 

Update 12/12/18: We have obtained new information about this incident, which you can find here.

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