Earlier this spring, I wrote about my experience building a Raspberry Pi-based Aircraft Tracker and then taking it for a test flight around the traffic pattern at Hayward Airport in the San Francisco Bay Area. At the time, I mentioned that our wet winter in Northern California limited my ability to take it very far and really see its utility. After some wait for better weather and finishing the aircraft’s routine annual inspection and maintenance, it was time to take it out for a longer flight and see how the tracker worked in more realistic conditions.
For this flight, I went from Hayward Airport (KHWD) to Tracy Airport (KTCY), a relatively small uncontrolled field 33 nautical miles to the east. Tracy serves as a convenient airport for landing practice as it is less busy than airports in the heart of the Bay Area. Figure 1 shows the route of flight as displayed on the Foreflight Electronic Flight Bag software with the tracker engaged. Livermore Airport (KLVK) was chosen as an intermediate waypoint for navigation.
Figure 1. Route of Flight from Hayward to Tracy
Figure 1 also provides a good illustration of what the tracker shows in the display. Note the aircraft traffic displayed south of the route, including at least two easily identifiable airliners, United Flight 1978 [UAL 1978 in the lower left] and Southwest Flight 1948 [SWA 1948 in the lower center]. The arrows and line indicate direction of flight. The length of the line shows relative speed. The letters and number below the arrow is the aircraft identifier, and the number above the arrow is the altitude in hundreds of feet. So, United Flight 1978 is flying southwest at 10,400 ft, while Southwest Flight 1948 is also flying southwest at about the same speed but at 8,000 ft. A diamond indicates that directional data are not available, while a lack of letters and numbers below the symbol indicate that the identifier data are not available.
My first verification of the system is shown in Figures 2-4. Figure 2 shows the view out my own windscreen as I am flying east next to Interstate Highway 580 (I-580) approaching the intersection of Interstate Highway 680 (I-680--the line off to the left). Figure 3 shows my own tracker-displayed aircraft track, flying east along I-580 at 2,800 ft altitude. Finally Figure 4 shows my altimeter reading of 2,900 ft., roughly matching the altitude on the display. (The altimeter is read like an analog clock with the small hand on thousands of feet and the large hand on hundreds of feet. Note there is a slight delay in the reporting, and I was climbing at the time.) So, the first check of the system proved to go well and displayed my own aircraft track.
Figure 2. View Flying East over I-580 approaching I-680
Figure 3. My own aircraft track as shown on the map display
Figure 4. Altimeter reading of ~2,900 ft (Note slight delay in reported altitude.)
The real test, and value of the system, came on the return trip. As I returned along the same route, I had two instances in which there was nearby traffic, and the tracker proved its value. I managed to capture the first in Figure 5, below. As I am approaching Livermore Airport at 3,300ft, I see an aircraft on the display fairly near my location at 2,000ft heading west. Though my heading information is not displayed, I know I am also heading west. From the display, I can see that the aircraft is actually behind me and 1,300ft below me. It is also low enough and close enough to the Livermore airport, that it is likely to be landing there, so it is not a factor for me.
Figure 5. Aircraft Traffic (arrow at 2,000ft) below me and behind me (diamond at 3,300ft).
Sadly, I was not able to get a good photo of the best use case. As I was descending back to land at Hayward, I was already communicating with the Hayward control tower, and they called out to me to look for traffic (an aircraft) above me and to my left. I looked at my iPad display to see the aircraft icon heading in the same general westerly direction but off to my left and reporting an altitude 1,300 ft above me. I then knew where to look and visually found it instantly. I could confidently call the tower to advise them that I had visual contact with my traffic so we could avoid each other. In practice, such a quick confirmation lessens the controller’s workload, and they are often appreciative. In this case, he waived my next waypoint reporting requirement and cleared me to land.
This is where the tracker really proved its value. My initial optimism was confirmed. I expect to use my Arm-powered tracker for many flights to come.