An instrument rating entitles a pilot to legally navigate an aircraft when the weather is bad enough that he can’t see outside.  A pilot who is not instrument-rated must always stay out of the clouds. If the weather is such that he can’t do that, he must stay on the ground.  

The training required to obtain an instrument rating is extensive.  In most cases, it takes a pilot longer and costs him more to obtain the rating than it did for him to get his pilot’s license in the first

place. But without an instrument rating, a pilot who flies into clouds will quickly become disorAgua Dulce Crash Siteiented, be unable to keep the aircraft "right side up," lose control of the aircraft, and crash. According to one popular article, the life expectancy of a non-instrument rated pilot who wanders into the clouds is about 178 seconds. 

"Technologically advanced aircraft," such as the Cirrus, are equipped with sophisticated autopilots that are capable of keeping the aircraft right side up. That may tempt pilots who don’t have instrument ratings to fly through the clouds, thinking they can always rely on the autopilot if things get dicey.  But that thinking is illegal and dangerous. 

Cirrus N427MC crashed near Agua Dulce, California.  The pilot and his two passengers were killed. The weather, according to the NTSB preliminary report, was cloudy. (As the NTSB put it, "instrument meteorological conditions prevailed.")  But the pilot, Dale Smet, did not hold an instrument rating.  (Though the NTSB report doesn’t mention that fact, Smet’s piloting credentials can be found here.)    

Witness accounts are consistent with this accident being caused by a non-instrument rated pilot venturing into the clouds, losing control of the aircraft, and crashing.  According to an article appearing in the Signal, one witness saw the aircraft come out of the clouds while out of control:

[The witness] was riding her horse along Canyon Quail Trail when she heard the plane’s engine. Moments later, she saw a white plane spinning out of the clouds. It flew over her head –  the plane was about 40 feet above the ground and plummeting fast.

Other witness accounts are similar.  

An overconfident pilot is a dangerous thing.