The following is a long post but I thought it might be interesting to anyone considering these technologies. It was posted on the PocketFMS Forum by a European user as his first experience of the ZAON XRX. Other posts suggest that FLARM is becoming increasingly popular for GA in Europe.
Cheers,
Ron
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Heinz,
Yes, I was able to take her out on my flight from EHHO to EDWJ and back again, so here are my first impressions based on some basic questions that I had before we took off.
Q: IS THE PLACE WHERE YOU PUT THE XRX IN THE COCKPIT SIGNIFICANTLY IMPORTANT?
A: YES, it certainly is!
During this first flight, I found two reasons for this (maybe there's more?):
(1) The aircraft we were flying with is an older type Socata Rally with an almost fully curved dashboard; not having an anti-slip mat caused the thing to slide and turn on the little flat piece in the middle, the power- and headphone wires pulling on it being the main reason for turning. With only that one flat surface available in the Socata, convenience of operation was out the door...
(2) Another effect that I observed was the indication of the own plane's heading, which I believe was caused by the position relative to the avionics and compass: on certain positions in the cockpit the heading was off as much as 140 degrees (!), moving it some 30 centimeters sideways resulted in a correct indication.
Q: HOW WELL IS TRANSPONDER-EQUIPPED TRAFFIC DETECTED?
A: (this part of my PiREP might be a little premature, since I only tested the XRX during this one flight; so this piece has to be taken with reservations!)
First some known facts, that are also mentioned in the manual:
- transponder-equipped aircraft that are not triggered into responses are BY DEFINTION not detected (this includes traffic flying below radar)
- transponder-equipped aircraft flying in your own plane's cone of silence are not (or barely) detectable
- configurable thresholds can be set to limit relative distance and relative altitude
My observations:
- detection on lower altitudes is significantly worse than higher up; not only detection is worse, also the indication of distance seems to be of lesser quality (the manual has a FYI mentioning about a distance indication being up to twice the real distance while on the ground, but this also seems to be the case while flying below 1000 feet). During this first flight only 1 out of 4 other planes that we saw was detected (both we ourselves and the other traffic flying below 1000-1300 feet AGL), quite a poor score IMHO!
- detection of traffic higher than roughly 1500 feet AGL seems to be excellent (all other traffic that we spotted was also detected by the XRX)
- setting a high threshold on relative distance (6NM) and relative altitude (+/- 2500 feet) makes the XRX to be be 'really present' in the cockpit, drawing too much attention to itself (I found myself to be glancing over at the XRX in sort of a reflex with every beep it gave, which I feel takes too much of my attention away from scanning the skies - this certainly is not to be ignored!). Setting relative distance to 3NM and relative altitude to 1500 feet improved that 'pitfall' significantly.
- indication of direction: the traffic the XRX detected was usually in the indicated quadrant. When an airplane departing EDWJ immediately after we did was crossing our path a few hundred feet above from right-behind to left-behind, I was able to observe when the XRX was changing the indication accordingly. I was in for my biggest disappointment of the day: only when the crossing plane was at our 7-8 o'clock it changed the quadrant Maybe it had to do with the PA28 that -at that same moment- was flying about 2NM + 600 feet of us, that it was 'paying less attention to the crossing plane behing'. I just don't know, but if this behaviour also applies to the other quadrants and to traffic considered to be 'primary threat'......... (hmmm, don't want to think about that just yet)
Q: ANY BUGS/MISSING THINGS IN THE SOFTWARE?
A: Yes, I found one: regarding callibrating the internal altimeter while being on the ground: not being able to callibrate using negative alitudes (called Flight Levels by the XRX) there's limitations based on airport elevation and QNH. Yesterday QNH at EHHO was 1029, field elevation 40 feet; the XRX showed FL001 (100 feet), so recallibration (actually initial callibration was required. The XRX however does not allow you to put in negative FL's.
Instead, I had to callibrated in-flight, subtracting 30 feet for every hPa from the indicated altitude (I can't imagine this to be the best way to callibrate when you're flying alone, so I will put in a change-request for this with Zaon, asking them to allow negative FL's during callibration)
My first (maybe premature) conclusions:
- cockpit-design and positioning of avianocs does greatly affect the readouts of the XRX's built-in compass that indicates your own plane's heading
- the XRX cannot be trusted to detect traffic equally well in all situations, my first impression is that when flying below 1300 feet AGL it's to better turn it off completely (the readouts that we got were incorrect, so no use to even consider the XRX in those situations, is there?).
- even with the directional indication down to a single quadrant, about half of the sky remains to be scanned (which of course is a lot better than not receiving any indication at all)
- if the XRX is getting onto your nerves by it's detections and alerts, decrease the tresholds for relative distance and altitude immediately! (as we all know: flying the plane remains THE most important thing to do, don't let any device endanger that - including PocketFMS)
- my next flight with the XRX I will ignore the detection-beeps, and just pay attention to the advisories and alerts; I found my regular scanning of the skies to be degrading a little, but maybe that had to do with me being anxious to find out how well the XRX performs.
IS IT ALL BAD?
NO, CERTAINLY NOT!
From the previous you might get the impression that I was in for a major disappointment.
Fortunatley this is not the case, because there are a number of important positive qualities as well:
- First and most importantly: during this first flight the XRX did detect other traffic before we did on at least three occasions.
- It also once detected traffic that we never even saw (the XRX indicated the traffic to crossing behind and 600 feet below and descending at 2NM distance)
- It correctly ignored traffic with relative distance and altitudes beyond the set threshold (that is: we did spot some distant traffic that seemed beyond the threshold, and also a rescue-helicopter flying at least 2000 voet below that it disregarded)
- Battery pack that bought with it (the small one) does indeed have the advertised capacity: earlier this week I kept the XRX running on my desk for about 8 and a half hours straight!
Well, you got my message I presume: I'm not all Halleluja just yet, but am certainly not disappointed either!
Some lessons learned today, and some new experiments need to be conducted to find out how the XRX can be best used from a technology point of view, and how to effectively incorporate working with the XRX in my normal flying routine.
I guess the most important lesson that I learned today is that the XRX has a strong tendancy of providing you with a false sens of safety and comfort, which holds the risk of decreased See-and-Avoid skills over time! (similar to GPS-es drawing people away from basic navigation skills using only a paper chart). In my opinion, this fact alone should be the basis for a strong discussion on whether an integration with PocketFMS should be developed, because such an integration would greatly increase the false feeling of safety by presenting an accuracy on a moving map that really does not exist!
Hope this preliminary PiRep will help others.
Blue skies,
Marcel
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http://www.zwakie.com
PocketFMS running on: HP 4700 with Windows Mobile 6
(Zaon PCAS XRX hopefully filling in the gaps
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