Weather and Flight Experience
I was flying a scheduled cross-country "training" flight with a new co-pilot who was working on his upgrade. We had completed an uneventful flight from San Antonio to McAllen, Texas, and were preparing our return trip and discussing our IFR flight plan. I might add that the month was July, the temperature approaching 100 degrees and afternoon thunderstorms possible, if not likely.
About 3:00 PM, my copilot got a weather update and was advised that a band of thunderstorms were quickly developing southeast of McAllen and were expected to move northwest across our route of flight. We decided to file a route that would take us northwest toward Laredo and then northeast to San Antonio which would allow us to get in front of and around the weather system (a 300 mile trip).
We taxied out and while doing our run-up, the tower gave us a weather update, telling us a thunderstorm was developing about a mile north of the airport with "cloud to cloud" lightning, gusty winds but no rain at that time. We were cleared for take-off on runway 13 and I requested a right turn out to put us further from the ominous clouds. (It should be noted that the remainder of the sky was severe VFR.) I was switched to departure control, cleared to 6000 feet and at that time requested a course deviation to the south on a westbound heading off the filed northwest victor airway in order to remain well south of the storm system. At that time, I noticed clouds building and some cloud-to-cloud lightning.
ATC allowed us to proceed westbound for about 15 minutes (25 miles) and then advised we were going to enter restricted airspace (Mexico) if we could not turn north in the next few miles. ATC gave a "suggested" heading of 350 degrees, stating their radar showed no activity on that heading. After again checking our stormscope we saw we were about 15 miles west and slightly south of the echoes. I advised ATC we were level at 6000 feet and were turning to the suggested heading.
The leading edge of the IMC did not appear threatening and no lightening was observed in the last 10 miles. I set up the autopilot and switched it on. Almost immediately after entering the IMC, there was an intense flash of lightening followed by the VSI "blurring" to 2000 feet per minute ascent. I switched off the autopilot. I observed the attitude indicator showing a 70-degree angle of bank to the left and felt the plane trying to roll over on it's back. The altimeter was rapidly winding upward and the airspeed had increased. I applied and held hard right aileron, appropriate rudder and reduced power; not much could be done with pitch. During the next few seconds we gained 1200 feet in altitude, turned 180 degrees counterclockwise and then "spit out" into the clear air, free of the meteorological forces.
The remainder of the flight was uneventful and I had time to reflect on my past "unusual attitude recovery while under the hood" training; in this case, a very beneficial phase of learning. After seven years of flying in our Honolulu division, I never realized south Texas IMC was so exciting!