Date: 202012
Local time of day: 1201-1800
Location: ZZZ.TRACON, US
Flight conditions: IMC
Weather elements / visibility: Icing; Turbulence
Aircraft: MD-11
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Cargo / Freight / Delivery
Flight phase: Descent
Airspace: Class C ZZZ
ATC / advisory: TRACON ZZZ
Aircraft component: Pitot/Static Ice System
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Pilot Flying; First Officer
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Human factors: Workload; Human-Machine Interface; Troubleshooting
Anomaly: Aircraft Equipment Problem Critical; Deviation - Altitude Crossing Restriction Not Met; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Inflight Event / Encounter Weather / Turbulence
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Aircraft Equipment Problem Dissipated; Flight Crew Became Reoriented; Flight Crew Overcame Equipment Problem; Flight Crew Requested ATC Assistance / Clarification; General Maintenance Action
Contributing factors: Aircraft; Weather
Primary problem: Aircraft

Narrative: On departure climbing in icing conditions with engine and airfoil anti-ice on the Captain airspeed and altitude alerted to 40 feet [difference] from First Officer and airspeed 30 kts. [difference]. After a few minutes; alert cleared; and everything was normal up to cruise altitude. Flight continued normal until we descend into icing conditions. Radar showed scattered precipitation and ATC reported turbulence ahead. At 14;000 feet we got into heavy rime ice. Captain airspeed indicator went to zero; autopilot disconnected; FADEC went to alternate all 3 engines; LSAS (Longitudinal Stability Augmentation System) all failed. I started hand flying checking FO (First Officer) and standby instruments; First Officer notified ATC of the failure of our airspeed and altitude due to ice. The First Officer instructions looked to be reliable compared to the standby; so I transferred control of the aircraft to the First Officer and assumed Pilot Not Flying duties doing the checklist. After about 10 minutes Captain airspeed and altitude started working again. We were given a speed restriction of 260 kts. or less and to cross intersection ZZZZZ at 14;000 feet and then cross ZZZZZ1 at 12;000 feet. The incident happened just after ZZZZZ. We were not able to make the restriction at ZZZZZ2. I told the FO to stop descent until we were sure of the instrument readings while we were communicating with ATC telling them of our situation. We cross ZZZZZ2 at 13;800 feet about 280 kts. I took control of the aircraft back from the First Officer and continued the arrival and approach via ATC instructions.We were immediately aware of the malfunction. There were multiple alerts and warnings going off when it happened.After landing the mechanics did a CFDS (Centralized Fault Display System) check which showed a MSC (Miscellaneous Systems Controller) failure. Look like the Captain pitot tube was not being heated properly and descending into the icing conditions cause it to become blocked. Immediate corrective action was taken by both me and my First Officer to fly the airplane and contact ATC.




Synopsis: Captain reported that while flying in heavy icing conditions the autopilot disconnected and the airspeed indicator went to zero. Subsequent maintenance inspection determined that a pitot tube was not heating properly and had become blocked.