Thunderstorm Avoidance
Thunderstorms are not to be taken lightly. I know you have probably heard that many times in your flying career. Weather related accidents account for approximately 25% of airline and GA accidents.
The Airman’s Information Manual suggests giving a 20 mile berth around thunderstorms. If you are an experienced aviator or a newbie please take this piece of advice seriously. At one flight school where I taught, we had the policy of maintaining a 25 mile buffer around isolated thunderstorms. A bit excessive you think? Maybe, but safety is a good thing!
On this particular day, I was operating a Bell Jet Ranger helicopter during a power line patrol. Power line patrol by itself offers numerous challenges. The job consists of flying along electric power transmission lines at approximately 40 feet above the ground at 40 knots. The crew consisted of me (the pilot) and an observer. The observer is an employee of the power company and it is his job to determine which line(s) will be patrolled during the given day. As I fly along the lines, the observer is checking for anything out of the ordinary such as broken, cracked, or even shot out insulators, excessively large bird nests at the top of structures, or woodpecker holes in wooden poles. The observer knows the lines and he is also a great help in letting me know there is a crossing, and potentially higher, line in our flight path. That makes him a true safety asset!
It was late afternoon during the summer and we were about to finish up for the day. We only had about another 10 miles of line to follow before calling it a day. Up ahead, I noticed an isolated thunderstorm near our power line. I could see the heavy rain falling below the anvil shaped leading clouds. It appeared to be well beyond the end of our day’s work so we pressed on.
As we drew closer to the thunderstorm, we were suddenly tossed up on our left side like a dog toy in mid-flight! It seemed like we were 90 degrees to our normal cruise attitude and, to make it worse, we had the doors off on that hot summer day. I was able to recover and we did an immediate about face and high tailed it home. Forget the rest of that line, tomorrow is another day.
The destructive force of thunderstorms cannot be overstated. In addition to extremely heavy rain, they can contain strong wind shear, large hail, and severe turbulence, each of which can damage or destroy an aircraft. Take care when one of these bad boys is near your flight path. Give it plenty of respect and a lots of room, for safety’s sake.
Alan VanDoren is a 7000 hour ATP pilot. He has flown both fixed wing and helicopters as a police pilot, missionary pilot, flight instructor, and most recently as an EMS pilot. He has flown in five countries around the world and also teaches university level aviation courses in his spare time.
