C425 pilot reported approach and landing difficulties related to inflight ice accumulation.

Attributes
ACN	1312872
Time
Date	201511
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	IMC
Light	Night
Aircraft 1
Make Model Name	Cessna 425/441 Conquest I/Conquest II
Operating Under FAR Part	Part 91
Flight Phase	Descent
Route In Use	Vectors
Flight Plan	IFR
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Multiengine Flight Crew Commercial Flight Crew Instrument
Experience	Flight Crew Last 90 Days 13 Flight Crew Total 734 Flight Crew Type 140
Events
Anomaly	Deviation - Altitude Excursion From Assigned Altitude Deviation - Procedural Published Material / Policy Ground Excursion Taxiway Inflight Event / Encounter CFTT / CFIT Inflight Event / Encounter Weather / Turbulence

Narrative:

Cleared for the ILS approach. Turned to capture localizer; aircraft began to lose altitude quickly. Went below the glide slope enough that tower informed of low altitude warning; pilot was already trying to resolve the situation. Autopilot was disengaged in order to recover aircraft. Controls were extremely heavy and required more than usual force. Once recovered; broke out of the overcast and was high and fast. Pulled power back and aimed for the runway. Landed long and fast. In an attempt to stop the aircraft; ran out of runway. Attempted the turn off the runway to taxiway. Due to slick runway and taxiway; the aircraft did not brake very well and slid off of the taxiway. Due to light snow covering on the grass and frozen ground; able to apply power to aircraft and return it to the runway threshold. No damage to airport property or aircraft. Able to taxi to FBO without further incident. Upon looking at the aircraft; needed to activate device boots more often. There was a heavy accumulation of ice. Should have probably gone miss once control was regained and activated deicing equipment more often.

Original NASA ASRS Text

Title: C425 pilot reported approach and landing difficulties related to inflight ice accumulation.

Narrative: Cleared for the ILS approach. Turned to capture localizer; aircraft began to lose altitude quickly. Went below the glide slope enough that Tower informed of low altitude warning; pilot was already trying to resolve the situation. Autopilot was disengaged in order to recover aircraft. Controls were extremely heavy and required more than usual force. Once recovered; broke out of the overcast and was high and fast. Pulled power back and aimed for the runway. Landed long and fast. In an attempt to stop the aircraft; ran out of runway. Attempted the turn off the runway to taxiway. Due to slick runway and taxiway; the aircraft did not brake very well and slid off of the taxiway. Due to light snow covering on the grass and frozen ground; able to apply power to aircraft and return it to the runway threshold. No damage to airport property or aircraft. Able to taxi to FBO without further incident. Upon looking at the aircraft; needed to activate device boots more often. There was a heavy accumulation of ice. Should have probably gone miss once control was regained and activated deicing equipment more often.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.