Sometimes your best intentions just go horribly wrong. Such was the case as we flew a short trip back to St Louis one afternoon. Between us and our destination lay a line of thunderstorms. My first inclination was to divert all the way around to the west, passing behind all of this late afternoon summer convective activity. Visually the cells were well defined and clearly visible. Soon though we entered the clouds and lost sight of the buildups. We checked in with approach control and immediately informed them we needed to deviate left (west). The reply was that there was a break in the line ahead and others were getting through so he’d vector us through it. A CapeAir Cessna 402, going the opposite direction at 4000’, reported a smooth ride. Mistake number 1: Abandoning my instincts, premium weather radar and satwx and letting myself be led by ATC. We had two technicians on board and a donor patient. We descended to 5000’ as instructed and they turned us between two cells, or so I thought. KA-WHAM! Suddenly we are seeing purple on the radar and getting violently hammered. After a few seconds that seemed like forever, we came out of it and exited the clouds with downtown St Louis dead ahead. Mistake number 2: I never told ATC anything about the turbulence. On the ground the techs informed me that the patient had moved somewhat in the bed and the breathing apparatus had fallen and broken, but they were able to fix it. Mistake number 3: After we unloaded the patient, instead of filling out a Safety Report, I thought I'd just fire off a quick letter to ATC pointing out the error of their ways. This course of action left our management in the dark and caused ATC to start a full fledged investigation into this "service failure". Imagine my bosses delight when the FAA called to discuss it and he didn't know what they were talking about.
Eventually I ended up going to a meeting with ATC and my boss. Approach control showed us a tape of the incident, and clearly the path we flew was the same as the others, between two cells. Of course the others were at 4000' in smooth air, while we were at 5000' and getting hammered. Yes, you can get a difference in ride like that with only a 1000' change in altitude. Weather can be unpredictable that way. I have to say that ATC was pretty good about the whole thing, and we got a nifty tour of the facility.
Bottom line: Don't let someone else take over your job of weather avoidance. Second, don't fly through an area of bad turbulence and not say anything. If you tell ATC then they will know not to send someone else through there at your altitude. Finally, if an incident like this does happen, fill out the Safety Report and let the program run its course. It's there for a good reason. There's no fun at all in standing at the big green table and doing a rug dance. Nope, no fun at all.