Many pilots worry about colliding with another airplane in flight, but not nearly as many worry about power lines. According to FAA numbers, that’s a mistake. There are roughly 75 accidents every year involving wires and while many of them involve helicopters, not all of them do. As the three accidents below show, airplane pilots regularly find ways to turn a fun flight into a fatal mistake.
The first accident involved a Cessna 172, which crashed while flying low over the Mississippi River in Minnesota. The flight appeared to be an example of a general aviation pilot trying to recreate the Dam Busters mission, but with tragic results:
“After takeoff, the pilot proceeded south until reaching the Mississippi River when he proceeded to fly along the river at a low altitude. As the airplane approached a bend in the river, the pilot entered a shallow left turn to follow the river. The airplane subsequently struck power lines spanning the river that were located about 200 yards beyond the bend. Ground-based video footage and witness statements indicated that the airplane was at or below the height of the trees lining both sides of the river shortly before encountering the power lines.”
The video referenced in the NTSB report shows just how low the Cessna was flying:
Even at a leisurely 90 knots, the airplane was covering 150 feet per second, which doesn’t give much time to react to wires. Combine that with the winding river and it’s easy to see how wires could sneak up on a pilot.
Beyond just the wires, the NTSB report notes many other obstructions – the airplane flew “within 400 feet of the residences located along the river during the final portion of the flight.” That endangered people on the ground in addition to the pilot and his passenger. Of course it was also completely illegal.
In the second accident, a Citabria crashed near Lake Travis in Texas on a VFR day. The taildragger was on a local pleasure flight when a witness observed the airplane flying as low as 25 feet over the water. You can guess what happened, but as is increasingly the case these days, the pilot was recording the flight with a GoPro so we know for sure:
“A GoPro video camera was mounted to the airplane and was recording the accident flight. The recording captured the takeoff and the entire accident flight. The last portion of the video showed the airplane flying low over water for several minutes followed by a left turn over a field. At 0708:13 the airplane pitched up and began to increase altitude. At 0709:21 the airplane began to pitch down into low altitude flight and trees became visible under the airplane. At 0709:34 the airplane initiated a shallow bank to the right and at 0709:36 the camera was deflected downward and the impact sequence started immediately thereafter. A set of powerlines is visible just before the camera was deflected downward.”
Not all wire accidents involve buzz jobs over rivers and lakes. A surprising number of accidents occur after takeoff, like a 2012 crash of a Lancair. The pilot and the pilot-rated passenger took off from Belen, New Mexico, before sunrise. While the surrounding terrain is reasonably flat, a north-south power line is located just west of the airport:
“The investigation revealed that the power lines were barely visible on the horizon in the desertlike terrain during daylight hours… Evidence at the accident site showed that the airplane had collided with 25-foot high power lines about 1.2 miles west of the departure end of runway 21. “
There are a lot of problems with this flight, including the fact that the pilot-rated passenger did not have a medical and the pilot had a limitation for flying during daylight hours only. There’s also the question of why the airplane was only 25 feet high 1.2 miles from the airport. But it also highlights the importance of the background behind wires. In this case it was dark night but even in daytime, the flat desert of New Mexico would hide the wires quite effectively.
One reaction to these accidents is “don’t be stupid.” As usual, that’s a convenient way of ignoring a legitimate risk. Better to use these accident reports as a springboard to improve your flying habits. Here are some rules to consider:
- All rivers and valleys have wires. This is the helicopter pilot’s equivalent to “all guns are loaded.” Even if you’re sure that river valley doesn’t have wires strung across it, you should fly as if it does.
- Last time doesn’t matter. Just because you’ve flown a route at low altitude before does not mean you’re safe – wires get put up all the time and they don’t show up in NOTAMs. In the 172 accident, it’s possible that the pilot’s familiarity with low altitude river flights led to some complacency. The NTSB report mentions, “The pilot’s father also informed FAA inspectors that his son was in the habit of flying at low altitudes along the Mississippi River.”
- Fly above 500 feet. This is still fairly low – and certainly low enough for passengers to enjoy the view – but it puts you clear of all but the highest towers. Remember that anything above 200 feet must be approved by the FAA, so even flying above that altitude offers some modest protection (assuming you look at the chart). But notice that each of the three accidents mentioned above involved wires that were no more than 50 feet AGL!
- When in doubt fly over towers, not wires. It’s much easier to judge height over a steel tower than a thin wire, and even if you see a wire you might not see all of them.
- If you have to fly low, circle at high altitude first. If you positively have to fly at 100 feet (and you should ask yourself whether you really need to), first evaluate the area from a higher altitude. Look for towers or straight lines in the trees that might indicate power lines.
- Weather doesn’t matter; time of day does. Most wire strikes happen in day VMC so just because the weather is good does not mean you’re safe. However, low sun angles do seem to increase the risk for a wire strike so be extra paranoid at sunrise or sunset.