DA42 Twin Star
Flight Crew Commercial; Flight Crew Flight Instructor
Flight Crew Total 1700; Flight Crew Type 1000
Training / Qualification; Time Pressure; Situational Awareness
Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter VFR In IMC
Flight Crew Took Evasive Action
Weather; Human Factors
The weather enroute to ZZZ1 wasn't too bad. I would characterize the clouds as scattered around 9;000 to 1;0000 feet with periodic cells of precipitation. Low temperatures meant icing conditions so we avoided all precipitation. Preflight planning weather briefing was in agreement with what we were observing; and we listened to each Automated Weather of the airports we passed.The area was nearly clear skies. Few clouds if any and no observed precipitation within 20 miles. Winds and clouds were moving east; following a cold front which passed the day prior. We encountered one broken cell at 10;000 feet off our left and few clouds off our right. We climbed to 11500 feet and passed above and well clear of that cell within a short period of time.We stayed VFR; away from known icing conditions and moisture. The ride was uneventful. On the ride back; I expected the same weather. Conditions at my destination were VFR with scattered clouds up high; and a nearby airport was reporting the same. I did not check one of the airports enroute.  Radar returns on the map showed the same few cells scattered without only light precipitation. In the same region we encountered what I believed to the be the same cell we crossed over in the previous flight. We took note of precipitation left; right and ahead to the left. With a large enough gap of scattered clouds ahead to the right. We continued; and I made the decision to climb up to 10;500 feet to determine the height of the clouds. The clouds which were still only 500 feet in height; were now based around 10;500 feet.I made the decision then to climb to 12;500 feet to cross over them. I knew we were less than 30 minutes from an area which previously was nearly clear skies. Upon reaching 12;500 feet; I started the timer and we continued to cross well above the layer. I would describe this layer to be 6/8 to 7/8 as there were often breaks where we could see ground and see that the layer was not very thick in height. Roughly 10 to 15 miles; 5 to 8 minutes we noticed the clouds were becoming higher altitude; and we were losing spacing from them. We maneuvered around them as best we could; but would need to climb to stay above them and away from icing conditions. I absolutely knew that we would not be putting the airplane into known icing conditions. At this point; turning back didn't seem to be any more promising than continuing on course. We had confidence that the weather in the area was better beyond this cell; and we just witnessed the weather make a change of heart behind us.At this point; I knew that things could turn worse. As contingency; we began direct course for an airport with good weather. In the event that we reached 30 minutes above 12;500 feet or encountered any ice; we would immediately descend through the nearest break and land the airplane.As we continued; the clouds continued to rise. Still broken and overcast beneath us; we were faced with few options. Climb higher; enter known icing; or drop through a break and hope there is not precipitation around which would become ice.Entering icing conditions was not an option; or if anything a very last resort. Hypoxia was our biggest threat at altitude; and we were well aware and cautious of any symptoms. Luckily; I have had the experience of an altitude chamber and know my symptoms and signs. But we had to climb higher to avoid the icing conditions. We climbed up to 14;500 feet briefly and descended back down when able. Then the weather cleared up; the clouds became scattered; and we were able to descend back down to 8;500 feet. A total time of 24 minutes was observed above 12;500 feet. I would estimate that only 2-3 minutes were spent above 14;000 feet. No signs or symptoms of hypoxia were observed. The remainder of the flight was VFR and uneventful.The challenge was the lack of weather reporting equipment to determine the weather enroute; but this is not an excuse. I will exercise more resources such as a phone briefing or additional charts next time. I will also remember to never expect the weather to remain the same. Next time I will remember my favorite motto; Plan for the worst; and hope for the best.
A flight instructor on a VFR flight reported encountering unexpected IMC weather and momentarily climbed to 14;500 feet to avoid clouds without oxygen.