UAV - Unpiloted Aerial Vehicle
Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Commercial; Flight Crew Multiengine
Flight Crew Last 90 Days 50; Flight Crew Total 6000; Flight Crew Type 50
Deviation - Altitude Excursion From Assigned Altitude; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Regained Aircraft Control; Flight Crew Took Evasive Action
Weather
While returning to base from an operational mission; aircraft encountered high cloud tops; and heavy precipitation in very low temps. Before reaching the clouds formation; crew ran the icing checklist and asked for higher because they could not determine cloud base. ARTCC approved a climb from FL240 to FL280. However; despite attempts to avoid the icing conditions; the aircraft began to accumulate ice and the aircraft lost almost 4;000 feet. Center inquired if crew needed assistance and offered an altitude block once crew explained they were having difficulty maintaining altitude due to the icing conditions on the aircraft. Center approved and the crew maintained FL210B240 until clear of the weather. Once clear of weather; crew continued on without further incident.
Pilot of an MQ-9 Aircraft (Unmanned Aerial Vehicle) reported that due to weather conditions and icing they needed to change altitude in order to maintain flight.