Date: 201502
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Weather elements / visibility: Icing; 5
Light: Daylight
Aircraft: PA-60 600 Aerostar
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Personal
Flight phase: Cruise
Airspace: Class E ZZZ
ATC / advisory: TRACON ZZZ
Reporter organization: Personal
Reporter function: Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Multiengine; Flight Crew Flight Instructor
Human factors: Situational Awareness
Anomaly: Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Weather / Turbulence
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Diverted
Contributing factors: Weather; Human Factors
Primary problem: Weather

Narrative: Departed VFR direct to ZZZ with flight following.Approximately 20 miles from ZZZ; approach notified us that ZZZ was reporting 2.5 miles and snow. I requested an IFR clearance and received a squawk and clearance from [Approach] with instructions to climb to 4;000 feet and expect vectors to ZZZ ILS.Upon penetrating the cloud base we began to immediately pick up ice on all leading edge surfaces (mixed rime and clear) including front wind shield to the extent that within minutes we had absolutely no visibility through the front wind shield. At 4;000 feet we made an attempt to fly vectors to the approach; however; we quickly determined that wasn't going to happen. Ice buildup was just happening way too fast and we couldn't see out the windshield.We notified Approach that we were abandoning the approach and immediately turned around and headed back in the direction we came from towards ZZZ1. We were told to maintain 3;000 feet and cleared to ZZZ1. We attempted to maintain altitude; but could not because we were still in the clouds and we continued to pick up ice. Without request from Approach I descended under the ceiling to 2;500 feet and proceeded to ZZZ1 where after about 9 or 10 visual approaches (roughly an hour) we were able to shed ice on the windshield to make a normal landing. It was a learning experience I really do not want to repeat. ZZZ1 approach and tower were extremely patient and helpful with us essentially giving us carte blanche use of the airport. We finally landed on runway 14 which was a 9;000 feet long runway I had chosen in the event we could not shed ice before running out of fuel. I could see the runway out my side window as we passed over it; I just could not see the runway out of my frosted up windshield. The length of the runway would have given me enough time to attempt a blind (out the side window) landing in the event it became inevitable. What would I have done different? Probably turned around sooner. The problem is; the ice came on so fast and thick we really didn't even recognize it until it was almost too late. Just writing this gives me the shakes. I can't remember a time I was this close to death.The funny thing is; I probably could have requested a contact approach; received it; stayed out of the clouds and landed non-eventfully at ZZZ. Again; a real learning experience I do not want to repeat.




Synopsis: Aerostar 600A pilot reported encountering severe icing conditions after takeoff from a Midwestern airport.