The R5 Aircraft Proximity Alerter


What is it and how it works ?

The Proximity Alerter : 

The R5 Proximity Alerter is a passive device which detects  transponder replies of aircraft  flying in your vicinity and displays simultaneously both altitude, estimated distance, code and vertical trend of up to three threats. The R5 system can monitor simultaneously up to 10 threat aircraft. It implements techniques similar to those found in more complex and expensive systems used by commercial aircrafts (TCAS for Traffic Collision Avoidance System). Basically your transponder replies to two kinds of interrogators : Ground radar sensors and airborne TCAS anti-collision system. 


Ground radar sensors asks for both your code and altitude. Your on-board  transponder will replies by providing both the code and altitude if set to ALT mode or only your code. As we all acknowledge it is frequent to forget to set this mode ... Not a limitation for the R5 system which is designed to detect aircraft even if its transponder is in Mode A only mode. It will display the aircraft code and distance but no altitude information and no vertical trend whatever vertical range you set. Not all devices available in the market monitor Mode A only threats. 

TCAS anti-collision systems are mostly interested by your altitude and your distance. Thanks to a complex arrangement of antenna they can provide information about the threat azimuth. Obviously this kind of set-up is not easy to install on a small GA aircraft and rather expensive to acquire. Once a threat identify these sophisticated systems coordinate actions to be taken by the converging traffics to avoid a collision. Portable proximity alerters found on the market will not provide such guidances because they are purely passive and no communication occurs between them. To overcome this limitation at ProXalert we do think that affordable proximity alerter must provide you with as much information about threat traffic as the technology allows.This information must be delivered in a very organized way and simple to read because you are a busy pilot and not an Air Traffic Controller. 

The R5 is the only affordable system to display threat codes. Some will say this information is luxuous, but when you get use to it your will never flight without. Let's illustrate this advantage thru some real life examples :

1- You fly in a controlled area an your overloaded ATC forgot to mention the presence of a closing traffic. Call him an provide the threat code ... He could give you more information about this guy without spending to much of his precious time because he will immediately understand who you are talking about. 

2-  Since ten minutes you constantly see the same code. You could deduct that this guy is probably following a parallel or converging path to yours same general direction. You already identified this guy five minutes ago and now you know what to look for. Similarly a traffic was detected then disappeared then came back. Without code you can't say if this guy is an old friend or brand new one. As in the previous example knowing the code will help establish visual contact more quickly. 

3- Sometime automatic ATC asks you to squawk a certain code when following a recommend transit route. If you happen to see this code on your R5 system you will know with no doubt that this guy is following behind or closing just in front of you. 

4- In some European countries certain codes are reserved to Air Force ships. (ie codes ending with two zeros) If you see such code you will be better prepared to identify these threat aircrafts. This is also true for other critical mission aircrafts like fire fighters aircrafts (code 7076). As you fly with your R5 you will discover new methods to locate threat traffics and increase your safety. Obviously the R5 can tell you if a detected aircraft is experimenting emergency situation (code 7500, 7600 or 7700).

As we previously said affordable proximity alerters are passive devices that does'nt coordinate pilots reaction. Accurate information translates in a better understanding of your real situation. We added a vertical trend indicator to help  you be better prepared for an emergency avoidance by altitude. You will immediately know if it is preferable to climb, descent or level. 


Most of us fly in metropolitan areas where traffic is heavy. It is therefore more and more frequent to fly surrounded by fellow pilots. A modern proximity alerter can't anymore afford to provide information about a single threat unless you only fly cross country. A threat could pop up in very few seconds and replace the one you was trying to locate, this is a very disturbing situation. With the R5 you get the three closest threats. They are automatically ranked by altitude or distance proximity. (Programmable thru menu)

The R5 displays the altitude in MSL or signed relative to you altitude thanks to the built-in altimeter. You have more time to locate the threats because you get a global picture of the surrounding environment. Less stress is more safety.

The R5 can detect aircraft even if they are very near. Some devices use your on-board transponder to get your altitude and therefore can't see traffic when they are too close due to the risk of mixing up radar replies. (> 0.25 Nm). 0.25 Nm means 1400 ft. So if you set a vertical range of less than 1400 ft, a  traffic closing from below may not be seen by these devices. Having a traffic just above or just below is one of the worst situation for visual identification.

Depending on the season and weather forecast the pressure could be very high. The R5 system is designed to accomodate this situation keeping its best accuracy. Whatever the mode you set absolute MSL or relative it will display a valid information by doing the proper math. Some devices assumes pressure is always above 29.92,  therefore they display smaller vertical separation in this case when threat fly below you at low altitude. This could create a stressing  situation.

For those who still continue to search for flying objects after their flight, we included a special ground mode to monitor traffics as a radar station does. You set the vertical range to Unlimited and the horizontal to 10 Nm and you catch traffics flying at up to 44, 000 feet, included cruising airliners.  



The Cruise Altitude Alerter : 


As we were on our way to pack more functions into this tiny package we think that providing a cruise altitude alerter will satisfy a large portion of our customers. How it works ? First of all you will have to set the range tolerance in the MENU to  matching your actual flight condition. The range tolerance could be set from 300 feet to 500 ft by 100 ft increment.  In most case 300 feet will be a good choice. You can set it once forever since the R5 memorizes its last configuration in a  non-volatile memory. 

In flight the R5 will monitor your current MSL altitude thanks to its built-in altimeter and will send a warning if you exceed the limits of the range tolerance. A suggesting audio beep sequence will tell you to climb or descend. At the same time a visual 'advice' will be displayed in the cruise altitude alerter status portion of the display.  A set of three arrows pointing up or down will suggest to climb or descend. 

Upon reaching of your cruise altitude press the SCA blue button, the R5 memorizes and displays your current MSL altitude for three seconds then displays the signed difference between your current altitude and the target you previously set. If you decide to change to another cruise altitude you simply have to press this same SCA blue key to disable the cruise altitude alerter. When reaching your new cruise altitude press the SCA button to re-activate it. Simple ! 


The A/C transponder tester :


The R5 system monitors threat aircrafts transponder but what about yours ? Knowing that your transponder sends accurate information will further increase your safety. TCAS and other proximity alerter will report proper information to their crew.

Reduce the horizontal range up to displaying a 'X' as the H range and the R5 will display both your code and altitude. It is a good practice to include this task during the first minutes of your flight. Always revert to normal horizontal range upon completion of this test. If you are 'covered' by radar when still on ground we recommend to perform this test before taxiing. 



The very low power consumption of the R5 (1 watt typical) is particularly well suited for usage in glider and superlight vessels. The unit accepts input voltage from 6 to 16 volts allowing operation from a small solar panel.



Usage notice : The R5 system will help the user establish visual contact with surrounding traffics. The user must be aware that in  some conditions the R5 unit may fail to detect threat aircrafts. The R5 unit user as a VFR pilot in command will stay responsible to avoid collision.

2003  Proxalert