One thing needs to be added about approaches before addressing the en route problem. With WAAS, we get vertical guidance on GPS approaches. Will that make it safer? Apparently not. More serious accidents occur while pilots are negotiating ILS than non-precision approaches. I don't know of any definitive information on the number of each type approach flown by general aviation airplanes, but I'd bet we fly a lot more non-precision approaches and will continue to do so until most users have WAAS and thus vertical guidance. Apparently the quality of the flying counts for a lot more than does the type approach.
When there is a terminal/en route loss of control, there is often a distraction. That distraction is often turbulence as found around thunderstorms as well as in frontal zones and areas of wind shear. Just a moderate amount of turbulence can make cloud flying a nightmare in a light airplane. Certainly what seems like reasonable bumpiness in clear air feels like it is magnified many times when we are flying in clouds. Flying in turbulence under a hood is not a very good simulation of what goes on in clouds, either. Just rain drumming on the windshield can be a major distraction.
Even though more weather radar information is available on the ground as well as in the cockpit, the number of thunderstorm-related en route accidents appears to be increasing.
The pilot in the accident related at the beginning of this story apparently had some form of weather in the cockpit. The pilot said that he had it and that it gave him information every five minutes. That's the general update rate on Nexrad from most of the weather services, so that is apparently what he had.
From the discussion, it sounds like this pilot was avoiding the areas of heavier rain. But that is not all it takes. There can be turbulence, really bad turbulence, around thunderstorms and in any clouds associated with thunderstorms, whether or not rain is falling.
The pilot said he lost "attitude." He might have meant "altitude" but, whatever, the airplane got away from him and turbulence was the likely reason for this.
Using Nexrad information for close storm avoidance is not a good idea. It's a strategic tool and should be used to avoid, not penetrate, areas of weather. If it is not used strategically, the NTSB folks are going to find an ever-increasing number of handheld Nexrad receivers in the wreckage of airplanes that are lost en route.
I remember the day this accident happened. It was an active day and visually the clouds in the area where he was flying would have appeared fearful. I say that only to emphasize the fact that if it looks mean to the eye it probably is mean, regardless of what a Nexrad picture might show. Best look at stuff like that from a distance.
High-performance singles and light twins stand out in the IFR/IMC accidents, with, I think, proportionally more singles on the list. There are a few engine-failure wrecks, in singles and twins, but these are a drop in the bucket.
One equipment item that these piston airplanes have in common is an autopilot. From the types involved, virtually all have this item of equipment.
For the person flying single-pilot IFR, an autopilot is an absolute necessity. However, if a pilot does not understand everything about the autopilot, it might cause trouble for the pilot when the going gets rough.
Many autopilots have disconnect parameters. Turbulence could cause these parameters to be exceeded. In that case, the autopilot would simply shut down and the pilot would have to hand-fly or, at least, reset the autopilot. These parameters are in the autopilot supplement in the pilot's operating handbook, and knowing all about them is important for each autopilot in each airplane that you fly. Pay special attention to any parameter that could be exceeded in turbulence.
Then there are some general autopilot features you need to understand if the device is to help you maintain control of the airplane in turbulence.
If the turbulence is convective, that means there are up- and downdrafts. That also means that if the altitude (or vertical speed) hold is engaged, the airspeed will reflect the effects of the vertical currents. The aggressive use of power may or may not allow the airspeed to be kept within limits. If the airspeed strays far away from maneuvering speed, that is definitely not good. Also, in a downdraft (or in ice or near the ceiling of the airplane), the autopilot can fly into a stall.