Challenger CL604
Flight Crew Multiengine; Flight Crew Flight Instructor; Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument
Flight Crew Last 90 Days 100; Flight Crew Total 14200; Flight Crew Type 2200
ATC Issue All Types; Deviation - Altitude Excursion From Assigned Altitude; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter Weather / Turbulence; Inflight Event / Encounter Loss Of Aircraft Control
Air Traffic Control Issued New Clearance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Returned To Clearance; Flight Crew Regained Aircraft Control
Weather
Climbing out of FL330 we requested a deviation from Indianapolis Center right of course for a thunderstorm top. Denied deviation by Center until FL350. Entered tops of thunderstorm. Could not maintain directional control; course; or altitude; due to severe turbulence. ATC questioned us if we had deviated from course and told us to expedite climb to FL350 in 30 seconds or less. We informed unable to comply and reported out of FL340 at ATC request. After being handed to the next Center Controller; Indy Center asked us to contact them after landing.
After breaking out of a cloud deck we noticed a thunderstorm build up in front of us. We requested a deviation from Indianapolis Center to the north for the weather but were denied. We informed them we would need a turn soon. They authorized a deviation left of course; however; we informed them that would put us deeper into the storm. We experienced severe turbulence and were unable to maintain altitude or heading control. ATC asked us if we were deviating and we informed them we were not as we attempted to control the aircraft through the turbulence. They asked us to expedite our climb to FL350 and reach it in 30 seconds or less and we told them we were unable. After clearing the weather the controller told us on frequency we couldn't deviate without their permission and we informed them that we hadn't; we were unable to maintain heading due to turbulence. They gave us a number to talk to them about it after landing; which my Captain did.
CL604 flight crew reported altitude and course deviations resulted from an encounter with severe turbulence associated with thunderstorm activity.