Sylmar Hang Gliding Association

I promised to write a review of the Zaon MRX portable collision avoidance system (PCAS) and after using it for 6 or 7 flights, I think I can provide an estimation of its usefulness in our application.

For those who are interested but aren’t familiar with the unit, navigate your browser to www.zaon.aero and click on the MRX display for all the details.

You’ll find the MRX an iPOD size, plastic case with a short antenna for receiving transponder signals from other aircraft. It uses 2 AA batteries and I’ve found that the manual is correct in recommending NiMH rechargeables. I rotated two sets for a total of ten to twelve hours of flight and recharged them only because I like to have a full charge, not because they were out. I used a lower brightness setting for the display and that helps. Apparently, alkalines will not last as long.

The MRX is very light; the batteries double the weight

The manual is very informative and easy to understand. I had no problem deciding how to set the parameters of the MRX. However, the joy-stick-like main control button makes it easy to choose the wrong menu item and settings.

The display is OK when on the shaded side of flight; direct sunlight renders the red LEDs unreadable. An LCD display would be a great enhancement.

The audible alerts (there are two) can be heard only when flying slowly and when the variometer and radio are quiet. I mounted my unit with the display directly in my line-of-sight when looking at my 5030 so, the lack of an audible is not a problem for me as long as I glance that way often. My mount would be a problem for the ultimate, slipstream set but it is a small profile.

As for the alarms, the MRX beeps twice for an “advisory� and four times for an “alert.� It also displays the appropriate word for a few seconds. An advisory occurs when any transponder comes inside a range of the set parameter. Alerts occur when the transponder approaches nearer, depending on the range set. For example, when set at the default range of 5 nautical miles, the MRX gives an advisory when a transponder-equipped aircraft approaches within 1.5NM and ±1000 Ft. The alert comes at 0.9NM and ±700 Ft. Not to worry, the display indicates an aircraft when it is anywhere within the 5NM and ±2000Ft range. Almost all aircraft in the L.A. area are required to have transponders.

Again, I’ve only heard the audible once or twice but I’ve seen the “advisory� and “alert� messages flash several times. Usually, I just check regularly to see if anything is in the 5NM range.

The range is adjustable to presets of 5.0, 3.0 and 1.5NM. The smaller the range, the nearer the transponder can approach before returning an advisory or alert.

I haven’t had any reliability issues but, overall, the unit seems fragile; it wasn’t intended for open-air flight. I mounted it high so there’s less chance of damage in case of whack and I think the metal Simpson tie I used to create a mounting bracket will offer some protection. Putting it in a modified iPOD-type bumper case would help but probably limit access to the batteries which the manual says to remove, when not in use, for longevity.

The greatest feature is that, although the MRX doesn’t indicate the direction of approaching craft, it does indicate the transponder’s altitude and trend, ascending or descending, relative to the MRX’s position. It’s good to know that I can ignore the display because the approaching plane is already above me and going up.

So how was the MRX useful? For me, it has granted a bit more peace of mind, especially when venturing into the usual traffic areas. Last Sunday, for instance, I noticed the display indicated an aircraft at +100 Ft of my altitude 1.5 miles away. I looked and there it was, a Rutan Canard heading North through the dam canyon about 1 mile away. On the same run, I was gaining through 4200’ at West Towers with nothing in range. When the display suddenly lit up with something within 5 miles, I didn’t bother to look around very long. I pulled the string and headed back to the 1500 at 60+ until I was under 3800’. I originally set the MRX for the 3NM range but I find I like having more notice of anything in the space and the audibles obviously don’t bother me.

Last words: the MRX is a pricey little thing at ~$500 and I don’t believe everyone needs one. However, mine has given me a lot of comfort these last few weeks and, if just one or two are in use, pilots could radio warnings with the pertinent information such as, their altitude and the range, altitude and relative climb/descent trend of the approaching plane, to get all pilots looking around them. This is something to discuss club-wide, if any are interested.

Actually, I think $500 is not so bad for a little more safety. Anyone who would like to see my unit and the mount is welcome to come by at set up or breakdown. I won’t guarantee it but I think Joe Greblo is allowing demos with his unit. Keep in mind, though, that mine is an updated version and I think it works better than his, from what he’s told me. Windsports carries or can order the MRX so, avoid the shipping charge, if you decide to buy.

Very well written review, Jim.

Good news, bad news!
Price is now $550. from Zaon, but it's improved and now comes with a cable that will pipe it's audio signal into a headset (that's very good!). Aircraft Spruce and Supply sells it for $535. plus tax and shipping. Windsports is making them available for $500. +tx. and W/S pays shipping and insurance.

I started to write a satirical blurb on these things but chickened out because I thought some people would think I was serious. I was going to publicly suggest to Ken and Jim that we offer to sell subscriptions to our "MIG WARNING SERVICE". We would encode our 2 meter radios with a private PL code and provide this private channel to pilots who pay a fee to get real time, in flight, radio warnings of when the jets are coming through.

I can just picture a gaggle of pilots with half the pilots diving for safety and the other half circling "happy as clams".