Flight Crew Air Transport Pilot (ATP)
Other / Unknown
Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Loss Of Aircraft Control; Inflight Event / Encounter Weather / Turbulence
Flight Crew Diverted; Flight Crew Landed As Precaution; Flight Crew Took Evasive Action; Flight Crew Regained Aircraft Control; General Maintenance Action
Weather
Enroute on an empty reposition leg; we encountered severe turbulence and mountain wave near ALS. Aircraft began to climb in excess of 1000 fpm and accelerate near red line despite us slowing in anticipation to M .76. Upon acceleration I quickly went to idle thrust; and then deployed the boards to 1/4. At that time the plane began to encounter the turbulence. The plane banked to what looked like near or slightly over 30 degrees left and was rattled by heavy jolts of turbulence at the same time. The other pilot helped by grabbing the ailerons at which time we worked as a team. He tried to keep the wings level and descend as I adjusted power and boards to keep plane at a safe speed. We advised ATC of turbulence and need to descend to which they cleared us to FL370. We were unable to adequately see the altitude and told them we would be descending until we could get good control of the aircraft. ATC turned a couple of planes out of our way; and we recovered and smoothed out at FL350. After a bit and a visual check of the wings and control checks; we decided it was best to make a precautionary landing to get a better exterior inspection and contact our mechanic. Enroute weather also made us decide to get a better idea if any damage occurred before entering more possible turbulence. Upon landing; we contacted our mechanic; looked at the areas that he recommended for damage; and found none. We also looked at the chart he emailed to us from the maintenance book about weight to G force ratio; and we decided we were in the clear; and no further inspections were needed. The flight continued with no further issues.
CL604 Captain experiences severe turbulence over ALS at FL390 resulting in a 1;000 FPM climb at idle thrust and partial spoilers. Flight eventually descends to FL350 with ATC's approval; but the Captain cannot read the altimeter during the initial descent due to the turbulence. The crew elects to divert to inspect the aircraft for damage before continuing to destination.