As we all try to figure out contermeasures to what LEO’s may use in speed traps, there is a desire to figure out when planes are being used for VASCAR. While aerial VASCAR is (in my opinion), less cost effective than a trooper sitting at an onramp, LEO’s still seem to use this method, so after consultation with protias, we thought it would be helpful to have a thread discussing countermeasure options. Primarily my information below stems from my general aviation knowledge of collision avoidance systems. As you can imagine, in a small plane, collisions with other aircraft are like shark attacks for swimmers – they’re rare but always in the back of your minds. As such, there is a fair amount of time, energy, and money devoted to figuring out where other aircraft are. Here are some of the ways pilots (and potentially you) can be made aware of other aircraft. Some of this stuff I may take for granted so if anything needs further clarification, let me know. As I get feedback from folks, I will revise and update this. Also, if this is too long, let me know and I’ll try to condense it. Old Fashioned Transponders – Most aircraft are required to have a transponder which identifies the plane’s position and aircraft tail number to ATC (Air Traffic Control). Further, operating within the airspace of moderately busy airports (Raleigh-Durham, Greensboro-Spartanburg, etc) or within 30 nautical miles of the big boys (Atlanta, New York, etc), the transponder needs to report altitude as well. Transponders work by responding to interrogations from ATC facilities. Essentially, ATC sends out a ping that says “who’s there” and transponders of aircraft within range respond with “I am” in the form of a 4 digit squawk code and depending on requirements, an altitude. This Squawk code is given to the pilot by ATC and the pilot manually sets the code into the transponder. The actual code is irrelevant for our purposes here. Zaon has developed several devices they call PCAS (portable collision avoidance system) devices to listen for these transponder replies. Depending on the model you have, they will tell you the relative altitude and distance of other aircraft. The MRX will give you the distance and relative altitude of the nearest plane. The XRX will track several planes and give you positional information as well and will track the 3 nearest planes. Note, these typically only have a reporting range of a couple miles but that should be sufficient for VASCAR. I have one of these devices (XRX) I use when I fly and while they do increase situational awareness, I have found them to be a bit imperfect. First, I have gotten falses before which scared the living daylights out of me (for instance, reporting a plane at 0miles distance and 300 feet below me). Second, this device will pick up any aircraft’s transponder and there are a lot of planes out there, compounded by the fact that there are a lot of small airports near interstates where you will likely be operating. This consideration can be countered by also looking for nearby VASCAR lines, but your PCAS device may be chattier than you’d like. Finally, and potentially most importantly, for this device to indicate a plane, their transponder needs to be functioning and has to be within interrogation range of an ATC facility. In some mountainous places, or even flying at low elevation it is possible to be out of range of an ATC facility so you may not pickup operations in those areas/conditions. As an alternative to PCAS, better equipped planes use TCAS (Traffic Collision Avoidance System), but that requires you have a transponder that will receive traffic information from ATC and I don’t think they’d be too happy about people running those in cars and I doubt it’s legal. Plus, they are very expensive and you’d need an aviation GPS that can translate that data into something visually usable. Aviation GPS’ are also very expensive. PCAS Pros: Portable, Cost Effective (relatively), Should alert in most cases, Active Alerting (will alert you if there is a plane nearby) PCAS Cons: Potential for falses, No ability to verify a bogey, Coverage issues create potential no-alert situations ADS-B – The current methodology for identifying and disseminating aircraft locations is pretty outdated and imprecise. As part of the FAA’s NextGen ATC platform, they have developed the ADS-B platform (Automatic Dependent Surveillance-Broadcast). Essentially, rather than working off of radar, this platform requires that planes broadcast their GPS position and altitude which ATC then uses to determine everybody’s position. When an ADS-B equipped ATC receiver gets an ADS-B transmission from a plane, it then responds with traffic information on all traffic it knows of within 30nm of the plane in question. Additionally, each ADS-B location will also broadcast weather information (very important for pilots) Now, there are ADS-B receivers for sale. Primarily, these exist to provide in-cockpit weather without the need for an XM weather subscription. Some offer the additional capablity of receiving ADS-B traffic information. Some systems come complete, but most are designed to feed into an iPad aviation app or an aviation GPS. They will then display the traffic information on a moving map centered around you. But here’s the catch – As stated above, ATC only transmits traffic information within 30nm of a plane transmitting ADS-B. So, if you’re driving and there are no ADS-B equipped planes within 30nm of you, you will get no information. If there are ADS-B planes within 30nm, you will only get info on planes within 30nm of THEM. The deadline for ADS-B compliance is currently 2020 and there are rumors that the deadline will be extended as these systems can be expensive to implement. Needless to say, most smaller aircraft do no currently have ADS-B transmitters. A further disadvantage is that your receiver will be listening for ground-based transmissions that are not meant to be received by ground sources, which creates the potential for reception issues if you’re behind a mountain, hill, etc. ADS-B Receiver Pros: More Robust than PCAS ADS-B Receiver Cons: Expensive, Coverage/Compliance gaps, Will not provide info if no compliant aircraft nearby Other Options The primary function of the devices listed above is to assist in mid-air collision avoidance. Therefore, the main function is to let planes know what other planes are nearby and that might pose a threat. The information below is more geared towards generally knowing what planes are out there. Web/App Flight Trackers: One intriguing option is to use some sort of app or web-based software that reports plane positions as it will probably be far more cost effective than buying a separate piece of equipment. One app I found with a BRIEF google search that uses ADS-B data is http://planefinder.net. I’m sure there are other options out there such as FlightAware but I haven’t fully investigated these. I also don’t know how frequently these apps refresh the traffic data. Presumably, some apps can lookup ownership info of operating planes so you can see if it’s owned by a law enforcement agency. However, these would all require somebody to be watching the map to see what aircraft are nearby and the screen may be saturated with irrelevant traffic (do you really care if a US Air flight at 30,000 feet is above you?). Perhaps an enterprising programmer could design an app that filters out traffic above a certain altitude and those that are on flight plans to a specific destination Web/App Pros: Very Cost Effective, Should alleviate ADS-B reception issues, Web/App Cons: Reliability of app data, Refresh frequency unknown, May report too many aircraft, Requires monitoring - will not actively alert Scanners: Safe VFR (visual flight rules) usually requires pretty diligent communication to let other planes know what you’re doing and where you are. Presumably a plane running VASCAR should periodically broadcast its location and its current flight actions (maneuvering or circling over a specific location). To check for nearby planes, you could listen to the frequencies of nearby airports but that requires a lot of frequency monitoring and probably isn't practical. As Ersin noted, you could also listen for communication with LEO's on the ground. IF VASCAR is prevalent in your area, listening on LEO frequencies is probably not a bad idea irrespective of if its ground or aerial VASCAR you're worried about. Eyeballs - You could always try to look for planes, but small planes are VERY hard to see, even when you know where to look. Nighttime is probably the easiest as you can look for the beacon or strobe lights, but I imagine they can’t run VASCAR at night since they can’t identify specific cars. Conclusion: In the end, a PCAS type system may provide the most reliable method of reporting nearby aircraft, but be aware it is not foolproof and nothing is a good substitute for an eagle-eyed driver paying attention. FEEDBACK WELCOME!!!