King Air C90 E90
Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 35; Flight Crew Total 2700; Flight Crew Type 80
Situational Awareness
Aircraft Equipment Problem Less Severe; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence
Flight Crew Took Evasive Action
Human Factors; Weather; Aircraft
The event occurred during cruise on a medical transport. Flight conditions were in and out small storm buildups and intermittent IMC/VMC. Upon exiting an area of IMC a very large buildup/thunderstorm appeared in front of me in very close proximity. I had no time available to request deviation from my course to avoid the hazard. I immediately turned approximately 30 degrees right of course to avoid the possible storm cell.Contributing to this was the XM weather and radar did not accurately depict what I was about to fly into. Had I selected a different altitude I may have been able to see and avoid the area much earlier. My inaction created a situation where I had to deviate from my assigned route.
King Air 90 pilot reported deviating without clearance for a thunderstorm that suddenly appeared on the nose during transition from IMC to VMC. XM weather and the aircraft radar did not show the buildup.