• CopterSpotter 2021 Report


    HelicoptersofDC is dedicated to bringing DC residents the most accurate and up-to-date information on what's overhead and to foster collaboration and education about helicopter identification and mission profiles. This year's (January) GAO report found that 96.3% of helicopter noise complaints to the MWAA from 2018-2021 were unattributed to any specific operator - this is why we feel it's important to educate the community on helicopter identification in addition to reporting what is happening currently and why.

    I'd like to thank our Patreon supporters, their contributions cover server costs and allow me to invest in hardware to bring radio calls to the platform.

    Unique Strengths of the CopterSpotter System

    Many flight tracking sites like Flight Aware, Plane Finder and Radar Box remove flights as a paid service to the owner. Even ADSBExchange, which doesn't filter any flights, does not receive tracking information from most military helicopters due to the Code of Federal Regulations Title 14, Chapter I, Subchapter F rule 91.225 which makes an exemption to mandatory flight transponders for "sensitive government mission for national defense, homeland security, intelligence or law enforcement." This makes an enormous amount of helicopter flights over the NCR untraceable in any systematic way. As a result, we rely on user submitted photos and identification of helicopters in addition to a separate system that allows users to categorize helicopter radio calls to/from DCA tower.

    Acknowledgement of Data Shortcomings

    All CopterSpotter reports are voluntarily submitted, and thus cannot be considered a measured random sample of the full population of like events. One thing that can be reasonably expected from Copterspotter data is that the number of reports received represents the lower measure of the true number of such events that are occurring.

    A unique quality to Copterspotter data - unlike ADSB - is it inherently represents the helicopters that people notice. In other words: if a helicopter flies over a forest and no one is around to hear it, as far as CopterSpotter is concerned - it didn't happen. Another way of thinking about it: CopterSpotter is like the Nielsen ratings of DC helicopters: what helicopters D.C. residents are currently watching.


    Another inherent bias to the system is the location of its users: it was my (all of our) hope that in 2021 our geographical range would expand, and so with it would CopterSpotter data. However user data seems to still be rooted near their homes for now, thankfully we have several contributors situated along major helicopter routes.

    One bias we acknowledge is what we will call "rarity bias," or that someone would decline posting a medevac helicopter, for example, because it is too common and does not interest them. As a spotter, you can mitigate this bias by deciding whether you will post a CopterSpotter sighting before you see or attempt to photograph the helicopter.

    Types and Operators

    Luckily the DC area is uniquely positioned to benefit from CopterSpotter data because:

    1. The high proportion of military and government agency flights that are not reported on ADSB

    2. Operators can be reasonably inferred by aircraft type. If a user can identify type based on blades on the primary rotor, landing gear and tail shape, we can infer the operator with a high degree of accuracy.

    *See "Proportional Comparison of our Data to GAO/DoD" below for examples of operator overlap

    Transparency Statement

    We want researchers and residents to have access to this data so we have made an anonymized copy of the 2021 data set, after corrections were made to types based on provided images, available for download in the CSV format here.

  • Data Overview

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    Over 10,000 Spots in 2021

    Most spots on a given day:

    February 3rd: 96 spots

    January 20th: 95 spots

    April 19th: 94 spots


    The leaderboard to the left shows our most active spotters, who collect 1 point for each spot and an additional point for attached media. Presently transcriptions of helicopter radio traffic are worth 2 points each.

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    Monthly Spots by Type

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    Proportion of Day/Night Spots

    *For simplicity, daytime here is represented as between 6am and 6pm.
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    Spots by Day of The Week

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    Active Users and Unknown Spots

    Active users decreased proportional to unknown helicopter spots January through October.

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    2021 Distribution of Helicopters by Operator

  • 2 Big Reports

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    USGAO: Aircraft Noise: Better Information Sharing Could Improve Responses to Washington, D.C. Area Helicopter Noise Concerns

    Of substantial value to our project was Appendix II: a comprehensive dossier on each operator in the NCR including helicopter types and number of helicopters in operation.

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    DoD: Review and Assessment of Mitigation of Military Helicopter Noise

    One thing that appears in both reports is the phrase "helicopters are required to follow the helicopter routes and altitude restrictions
    established and enforced by FAA
    " yet in the previous paragraph they acknowledge frequent deviation from these routes. What is not mentioned nor shown on their limited route chart is the use of "Zones" that cover the NCR.

    Over a limited 2-month sample of the radio calls we collected from the last year, helicopters requested zones in 75 of 200 requests.

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    DoD and GAO Numbers

    While we can't draw an apples-to-apples comparison between these two data sources it is valuable to look at the data the two agencies provided side-by-side. The DoD report notes the difference in detail:

    "Government Accountability Office (GAO) Report GAO-21-200 counted 11,011 military helicopter flights within the NCR in 2019, including Department of Homeland Security flights, which is substantially lower than the 21,863 flights reported in CY 2020 by the Army, Marine Corps, and Air Force. However, it is important to note that GAO used available flight track data from FAA and limited its data collection to flights within 30 miles of Ronald Reagan Washington National Airport, which differs from the prescribed scope of this report."

    DoD annotation

    GAO annotation

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    Proportional Comparison of our Data to GAO

    Again, not an apples-to-apples comparison, but interesting to look at the proportional rates of our data compared to GAO, and we roughly fall in line with the ranking, though local law enforcement is relatively over-represented while air medical is relatively under represented in our data set. It's easy to infer why as local law enforcement is the most likely operator to fly circles over your neighborhood.

    While we fit our data as best we can to their categories, the following conflicts arise with type designations:

    • Unclear if Coast Guard is included in GAO's Military or Federal Law Enforcement category, omitted from our data here
    • B412 type is included in Federal Law Enforcement and Emergency support, most frequently Park Police but can also be Dept of Energy's 'Nuke Sniffer' helicopter
    • B06 is included in Federal Law Enforcement here as Park Police #N33PP however it can also be @Chopper4Brad's news helicopter: News here represented solely by R66 shared by ABC/CBS/FOX
    • B429 included in State and Local for Fairfax County Police,  similarly H60 used in Military, but both crafts are used less often by FBI
  • 2021 #CopterSpotter Most Spotted Award

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    The Air Force 1st Helicopter Squadron's primary mission is to be prepared to evacuate high-ranking personnel from the Capital area in the event of a national emergency. It also supports Washington D.C. area airlift for high-ranking Executive Branch, dignitaries, military leaders and other VIPs. The squadron also supports search and rescue missions. [Wikipedia]


    Spotting tips:

    • UH1N type helicopters have been in use since Vietnam, frequent breakdowns mean you might see this helo landed at your local playground or sports arena
    • Goes by call sign MUSEL
    • two blades on the main rotor when photographed
    • distinct whooping noise
    • dark blue with gold or blue and white stripe, commander flies grey livery with a yellow tail
  • The President's New Copter

    from burning holes in The White House Lawn to *almost* ready for action

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    The Sikorsky VH92A has been slated to take over for the aging VH3D. Through various operational tests this year it has had numerous setbacks and we expect testing to continue through 2022.

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    Issues and Overflights

    In early March Bloomberg reported new VH92A risked scorching White House Lawn.

    In late November Bloomberg report cited reliability concerns.

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    Present and Future

    This chart from The War Zone shows the current and planned distribution of Presidential executive air transports.

  • 2022 and Beyond

    Tweet Less

    Currently a bot tweets helicopters with ADS-B transponders over the NCR every 10 minutes. One of my top goal is to build a more intricate system that looks at craft patterns and will de-prioritize flights that are circling or landed for example. The goal being to lower the frequency of automated tweets to make the account more attractive to Twitter power users.

    Automated Copter ID with MAchine Learning

    We have been logging every photo to Roboflow (the founder is based in D.C.!) and intend to implement a computer vision model to include a "guess" at the helicopter ID when someone posts an unknown copter.

    Analysis of Radio Spots

    Since October we have been logging spotters' transcriptions of helicopter radio calls and will be thinking of a way to present this data next year.