My In-Flight Data Recorder

A while back, I discovered a little mobile app from Google called My Tracks. It’s basically a simple GPS recorder that then renders your track in various pretty ways. Here’s how Google describes it:

My Tracks records your path, speed, distance, and elevation while you walk, run, bike, or do anything else outdoors. While recording, you can view your data live, annotate your path, and hear periodic voice announcements of your progress. With My Tracks, you can sync and share your tracks via Google Drive.

And as you can see from the preview screenshots, it looks like a nifty little app:

My Tracks

Now that last page view on the right caught my eye. It had an elevation reading. And that got me to thinking, “My phone never touches the ground. It doesn’t care if I’m suspended by a mountain or air. I wonder if I can use this as an in-flight data recorder.” The answer is: Yes.

But where things get really interesting (and a bit entertaining) is in rendering the flight data. The app itself does an OK job, but it can be configured to automatically synchronize with Google Drive. That means my flight data is available on my desktop before I get home, and I can open it in Google Earth.

My first such adventure, a literal test drive, was driving from my house to a nearby pho restaurant. Loading that up in Google Earth gave me more or less what I’d see in My Tracks. But then there’s this curious little feature called “Show Elevation Profile.”

Haus to pho profile

That pulls up an elevation and speed profile. The speed profile has some rather profound spikes that are clearly errors, but these are easily mentally filtered. The remaining data seems to be what I remember.

Now this got me thinking. I said to myself, “Self, couldn’t this little app be used as an in-flight data recorder?” I decided to test my theory. I recently took a friend of mine from work up in my airplane for a short flight over his current house and the site where he’s building his new house. Before starting up the engine, I activated the app on my tablet, then tossed the tablet in the back seat and forgot about it until we landed. Later that evening after I had returned home, I looked inside my Google Drive folder, found the flight, and double-clicked it to view it in Google Earth.

Friend Flight

This is the entire flight. The airport is toward the south (the left side of the image), and my friend’s house is up north (the right side of the image). There are a lot of trees in the area, so we didn’t spot his current house right away. So we had to do a few turns around until we could get the right angle. Then in the upper-right of the image where the red arrow is, that’s when we turned south so we could fly over the site of his new house.

That highly-developed-looking area between Silverdale and Poulsbo that’s to the west (up) from our flight path is a nuclear submarine base. We avoided flying over that. We didn’t want to get shot down.

Looking at the elevation and speed profile, there were those occasional error spikes like what I experienced in my car. However, filtering those out, the speed seems just about right. The elevation doesn’t have those spikes, but the data is a couple hundred feet off consistently. I’ve noticed this is consistent across several different flights, and it’s why if I zoom in to the airport area, it looks as if I’m landing below the airport runway. It’s a bit annoying, but it’s an easy thing to mentally recognize and calculate away.

Friend Flight Landing

Now I must admit, I thought this was all pretty cool even for a simple, normal, uneventful, and short flight. But what if I tried using the in-flight data recorder for practice to improve my flying?

I own a Lake Buccaneer. It’s an amphibian, an airplane boat, with the propeller set high above the fuselage to make landings on the belly on water safe. It’s a flying brick, built strong and heavy, lots of drag, which means it’s not exactly what you’d call an “elegant” airplane. It has what one pilot called the glide slope of a dead cat. It has many very strange flight characteristics. It is, however, extremely versatile; it can land almost anywhere safely. Still, it’s not exactly an easy airplane to fly, so I took it on as a challenge to have tight landings and take-offs in less than 1,000 feet of runway.

Here’s one set of three cycles through the airport pattern. (For those of you non-pilots, the “pattern” is a rectangular pattern with one of the long sides of the rectangle being the runway.)

Short Field Practice

Seeing this data represented this way after the flight was thrilling. Notice how the loop on the far right is extended beyond the other two loops? That was the first pattern I flew, and I had to extend my downwind leg because there was another airplane flying a direct approach on an extended final. I extended my downwind to give him enough time and space to land and get off the runway before I came in. The other two patterns were pretty normal.

Again, filter out the speed spikes and the airspeed is becomes fairly accurate. And mentally add a couple hundred feet to the altitude.

One of the incredible advantages of viewing this data in Google Earth is that I can zoom in and out, tilt, pan, and otherwise see the entire flight from nearly every angle imaginable. So I zoomed in on the start of the runway, and I examined one of the three take-offs a bit closer. I was able to determine the exact point on the runway when I took off, which is where the red arrow is.

Take Off Role

Using Google Earth’s ruler, I then measured the distance. It’s less than 900 feet. Victory is mine!

I have no intention of and no interest in becoming a CFI (Certified Flight Instructor), but if I were to teach flying, I’d consider recording every flight and giving the student the data afterward. It would make for some pretty great post-flight review, I think. It certainly has been interesting and helpful to me at improving my skills so far.

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