By Robert N. Rossier, EAA 472091
This piece originally ran in Robert’s Stick and Rudder column in the August 2021 issue of EAA Sport Aviation magazine.
Anyone who has been flying for very long recognizes the potential for a midair collision. No matter how careful we are, there is always a chance that we’ll miss something or that someone will sneak up on us (or us on them) undetected. So, we keep our heads on a swivel, make accurate position reports, perform clearing turns, properly scan for other traffic, watch our ADS-B, and use ATC radar services when we can. Even with all that, aircraft can still slip through the gauntlet and pose a threat, even on a clear, sunny day.
Not so long ago, I had a close encounter with another aircraft while inbound to my home airport. I had just come across Block Island Sound and was descending as I flew northwest toward the airport when I heard a pilot in a Mooney make a position report just a few miles northeast of my position. The pilot reported being more than a thousand feet higher than I was, but since I expected he would be faster than I was in a pokey Britten-Norman Islander (BN-2), I figured I had better find that airplane and keep close tabs on his position.
Our primary means of detecting other aircraft is the visual scanning technique we learn early in our flight training. We scan the sky in sectors roughly 10 degrees wide, stopping to focus briefly before continuing our scan to the next sector. We intersperse this outside visual traffic scan with periodic scans of the instruments.
No matter how good or diligent we are, visual scans are anything but perfect. We can only focus clearly in a narrow cone of our visual field roughly the size of a quarter held at arm’s length. Outside that sharply focused area, our visual senses readily recognize motion. But if an airplane is coming straight toward us, there is no relative motion — just a sudden blossoming when the aircraft gets close. Other factors limit our visual scan as well. Hazy conditions make it difficult to see anything at a distance, as can the bright illumination that comes with low sun angles.
One way we can make ourselves more visible is to turn on our landing lights and strobes, which greatly improve the chances of someone else seeing us. As usual, I had my strobes and landing lights on, which I hoped might help the Mooney pilot spot me. And I was using my best scan techniques to try to spot him. So far, I was having no luck.
Within a few moments, a new target appeared on my ADS-B. It had to be the Mooney. Sure enough, it looked like our flight paths might soon merge. I called the Mooney pilot and asked if he had me in sight but received no response.
Pilots might not communicate for any number of reasons. Some might be uncomfortable with radio communication techniques. Some don’t see the need or prefer to keep quiet, especially when it seems like nobody else is around or listening. Pilots might be tuned to the wrong frequency, have the volume turned down, or not have a radio to begin with. For all I know, the Mooney pilot was simply distracted and missed my call.
Radio communication can be an important tool in collision avoidance, but it too can suffer from a variety of problems. We all know what happens when too many pilots make calls and step on one another’s transmissions. We have the case of a stuck mic, which effectively jams the frequency. We also have situations where pilots give inaccurate position reports. As much as we would like to give, hear, and believe in position reports as a viable collision avoidance tool, we can’t always depend on them.
In this case, the ADS-B said the airplane was there, so just to be safe, I altered course to put more distance between us. For some reason, the Mooney changed course with me. Not a good sign, and one I couldn’t quite explain.
There’s another collision avoidance trick that works well on a sunny day. If we can see our own shadow traveling over the ground, we can scan to see if other shadows are approaching it. Simple physics tells us that airplanes can’t collide unless their shadows collide. This day we had a high cloud layer, so no shadows were there to be seen. I had to rely on my own vision and the ADS-B. The thought crossed my mind that perhaps I was the one with the radio problem. Maybe the Mooney didn’t respond because I was not transmitting. The distance between us was growing steadily closer, and I was becoming somewhat anxious. Suspecting I had a problem, I asked another pilot for a radio check. “I hear you, five by five” came the reply. My radio was transmitting just fine.
Other tools in our toolbox can help guard against midair collisions. One of the best, when available, is radar services from ATC. Having a set of radar-enhanced eyes to look after us is a good insurance policy. Unlike ADS-B, radar can see other aircraft that are not ADS-B equipped, even if they don’t have transponders, and can give us a heads-up to their position, if not altitude. In this particular location, the ATC radar couldn’t pick up targets at our altitude. No help there.
It was beginning to look like a classic setup for a midair collision: a low wing aircraft — in this case, the Mooney — descending on top of a high-wing aircraft – my Islander. I still could not see the Mooney, but the ADS-B indicated he was there, closing in on me and descending right on top of my position.
We all know that technology is not infallible, and for a moment I was wondering if perhaps there was some glitch. Could there be a malfunction? Was the ADS-B acting up, somehow presenting a faulty image? Or maybe the display was just too crowded and made it look like we were closer than we really were. I zoomed in the display to get better resolution. The hairs on the back of my neck were starting to stand as the ADS-B showed the Mooney nearly on top of me. I could only imagine the sickening screech as the Mooney’s prop sliced through my empennage, the loss of control, and the horrifying tumble toward the Earth that would follow. Our altitudes were merging, and even though I could neither hear nor see the illusive Mooney, I finally broke off my approach and made a 360 for spacing.
It turned out it was my lucky day. A split second later, I saw the Mooney pass through my altitude and enter the pattern ahead of me. Still no calls.
Minutes later my wheels kissed the runway. The Mooney had made a touch-and-go and disappeared to the west. And I’m convinced that without the ADS-B, a midair collision would have been my demise.
Wherever you’re headed this summer, keep a sharp lookout. Use all the resources you have available to ensure against midair collisions. Lucky days come when you make your own luck.
Robert N. Rossier, EAA 472091, has been flying for more than 30 years and has worked as a flight instructor, commercial pilot, chief pilot, and FAA flight check airman.