Date: 201604
Local time of day: 1201-1800
Location: ZZZ.ARTCC, US
Flight conditions: IMC
Weather elements / visibility: Thunderstorm; Turbulence
Light: Daylight
Aircraft: Regional Jet 700 ER/LR (CRJ700)
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Descent; Cruise
Airspace: Class A ZZZ
ATC / advisory: Center ZZZ
Aircraft component: Pitot/Static Ice System
Component problem: Malfunctioning; Design
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Distraction; Confusion; Troubleshooting; Workload
Second reporter function: Pilot Flying; First Officer
Anomaly: Aircraft Equipment Problem Critical; Inflight Event / Encounter Weather / Turbulence
Detector: Automation Aircraft Other Automation; Person Flight Crew
When detected: In-flight
Result: Aircraft Equipment Problem Dissipated; Flight Crew Landed in Emergency Condition; Flight Crew FLC complied w / Automation / Advisory; Flight Crew Diverted; Flight Crew Took Evasive Action
Contributing factors: Aircraft; Weather
Primary problem: Weather

Narrative: While en route we were circumnavigating weather. First Officer (FO) was Pilot Flying (PF) and I the Captain was Pilot Monitoring. At this time we were IMC and receiving light to moderate turbulence at FL370. While circumnavigating the weather we were well away from any convective activity in what we were painting with our onboard radar. We did notice some 'green' returns on our deviation course; but nothing any more noticeable than that. The turbulence we received was continuous to occasional moderate turbulence at most - Flight Attendants and passengers were asked to stay seated. As we were exiting the area of turbulence I noticed the IAS was slightly decreasing with a red trend vector decreasing as well. I mentioned to the FO to add more cruise power since the trend vector was showing a decreasing value. At the time I requested this we were neither climbing nor descending. After adding power and the vector still decreasing I then informed him to set Climb power to prevent any further decrease of trend vector and airspeed. We could tell the winds were shifting and neither I nor he were sure if we were getting a slight wind shear at high altitude since the winds were changing quite a bit. At this time I requested lower altitude from ATC to help us increase airspeed. At no time did we get below Mach .70. I believe the lowest we indicated was .71 Mach.We were given a descent from 370 to 350 and all three airspeed indicators were showing a decreasing speed with a large decreasing trend even though we were in a descent. At this point we recognized we had blocked pitot tubes. Shortly after descending and throughout the descent we received numerous caution Msgs: Mach trim; Stall fail; rudder fault and rudder limiter cautions Msgs; 'Fadec 2' status messages for engine two and engine one also posted; IAS caution; EFIS Comp Mon IAS and ALT caution messages (these are the ones I remember). I (Captain) became the PF while the FO ran the QRH procedures. (Please understand that I am trying to recall all messages and events in the best order I can. Not necessarily were they all there together. Sometimes messages appeared; disappeared; and then reappeared. We were running the QRH procedures as best we could for the appropriate messages we saw.) During the descent I was utilizing Pitch and Power settings best I could and also listening to the air noise over the windscreen to provide the safest descent profile under the circumstances. At no time did I ever feel we were too fast (barber pole) or too slow (near a stall). We [advised] ATC somewhere around FL310; if I remember correctly; and informed ATC we wanted to land in [a nearby airport] since the QRH directed us to do so and it was within close distance to land utilizing normal descent rates; plus it had a long runway which I wanted to utilize for this situation. During the descent the FO was notifying dispatch we were landing at a divert airport. Also; some messages went away and airspeeds seemed to be normal; but then they would become erroneous again. During the descent my side seemed normal as well as the ISI and the FO's side abnormal; but at lower altitudes then the FO's airspeed became what seemed normal and concurred with the Integrated Instrument System (ISI) while mine was dropping showing near stall IAS; but the ISI; FO's IAS; and GS from the MFD were all providing data that seemed to elude we were flying safely. At this time we selected the Source selector panel ADC knob to the FO's side and left it there for the remainder of the flight.While descending through FL250 the autopilot did a rather abrupt wing rocking motion from right to left. I clicked the autopilot off and hand flew the airplane. Sometime later we tried reengaging the autopilot; but it wouldn't engage. Approaching the airport we ensured emergency equipment was standing by as a precaution and we elected to land runway XY for the extra landing length and winds were a little bit of a crosswind; but manageable. Unfortunately we did not have a glide slope to use as a backup and since it was a single FMS head unit we could not enable 'VNAV' since it seemed that used data from my side and that function was not usable. The FO then began calling out altitude and distance information to help me stay on a 3.0 degree glide path until I was able to utilize the VASI. We landed using flaps 20 (QRH directed with Rudder Limiter Fault) and taxied off the runway to the gate without any additional problems.There were numerous Threats in the situation. Weather; Erroneous instruments (IAS); numerous message both caution and fault messages. Fortunately we never were in an undesired aircraft state that I knew of other than trying to figure out what airspeed we were using. We also backed up ground speeds with ATC to do our best to ensure we were flying at safe speeds for the pitch and power settings used. As in any event we can always look back and think 'I could have done this or that better'; hindsight is always 20/20. What was an exceptional factor to flying this airplane safely was the use of good CRM. The First Officer was exceptional in all aspects in the way he helped me and ensured I wasn't forgetting to take care of necessary steps. I am very very thankful for the training has put into this high altitude pitot tube icing training as well as teaching solid CRM fundamentals and concepts to safely fly airplanes to the best of our abilities.


Second narrative: We began deviations to the left of course to avoid the convective activity. We were cruising at Mach .78 with a normal power setting. We were in IMC and the temperature was in the mid -50 deg C's Static Air Temperature. What started as up to a 15 degree left deviation turned into a 40 degree deviation to space ourselves from the storm. We began to encounter constant light chop with an occasional moderate bump. I slowed the aircraft to Mach .75. As we made our way around the storm we began a slow turn back to the right and turned direct. While we began the turn back to the right; we both noticed a slight dip in our airspeed. I continued to add power until I reached the max cruise limit setting. I originally associated the speed change with a wind shift and that it would pick back up. While turning back to the nearby airport; we saw another storm on the radar and asked if we could deviate as necessary and ATC acknowledged. Our airspeed continued to bleed down and the Captain commanded me to set climb power; which I complied with. Even after a minutes worth of climb power; we continued to see the downward trend in the airspeed. It was at this time I became aware of the possibility that our pitot system had froze with ice crystals. I stated this to the Captain and he agreed. All three airspeed indications were within 5-10 knots of each other and still showing a slowdown. We requested a lower altitude and were granted FL350. I did not move the thrust levers out of climb power. While descending we still had reducing airspeed trend. We requested lower again with ATC and were given FL310. I commanded the autopilot to descend at 1500 FPM and we still had a descending airspeed. The Captain noted that our GS was 500 knots and was constant. We continued our descent down and received a RUD LIMITER caution message. The Captain then assumed control of the aircraft and the radios while I started the QRH. The Captain [advised ATC]. While in the QRH for the RUD LIMITER caution; it states to land at the nearest suitable airport.At this point my airspeed indicator began to show a slower indication than the Captain's and ISI. We received an EFIS COMP MON; STALL FAIL; & MACH TRIM caution message within a minutes time span. While running the QRH for the RUD LIMITER; I saw the Captain was task saturated with flying and the radios. We were still in IMC and he was still deviating to avoid weather. I paused the QRH checklist and began to set up for the landing at the divert airport. I advised dispatch through ACARS that we were diverting due to RUD LIMITER caution and all pitot's possibly being iced over giving us erroneous airspeeds. Since we have no procedure for multiple erroneous airspeed indications; I crosschecked the ISI with both the Captain's and my airspeed to see which two most agreed. It was determined that it was the Captains so I selected the Source Selector to ADC 1. While descending from the mid to lower FL200's; we both became aware that the ISI had now appeared to recover and was indicating an airspeed around 280 knots. The Captain began to fly the aircraft off the ISI. We broke out into VMC and we switched controls so the Captain can talk to the flight attendants and advise the passengers of the situation. After he completed that; we decided to put the source selector back to normal to see if either airspeed came back. My side was more closely resembling the ISI and now the Captain's was far off. His speed was showing just above the low speed cue. Being unsure whether the shaker/pusher would engage; he switched the stall protection off. We choose to change the source selector to ADC 2. We switched controls again so the Captain could perform the landing. During the descent the RUD LIMITER caution flipped to RUD LIMIT FAULT status message. Through the synoptic page we determined that the rudder limiter had failed and was at a limited position. I continued on with the RUD LIMITER QRH and completed it. During the descent we had aL & R FADEC FAULT 2 messages post. We landed at flaps 20deg per the QRH with no further incident. We were able to pull off the runway and continue to the gate. At some point in the descent; the autopilot disengaged and would not re-engage. The cautions as stated above would disappear and reappear multiple times in the descent. At no point did I see any ice crystals form on the windows or wipers.Having multiple erroneous airspeed indications; in IMC; with no proper procedure to remedy it. After reviewing the events from the day prior; we could have ran the EFIS COMP MON QRH for the airspeed and altitude; but we were too task saturated at the time.


Synopsis: A CRJ-700 flight crew reported what appeared to be pitot icing at FL370 in IMC. The equipment affected were both airspeed/Mach systems; Integrated Standby Instruments; FADEC; RUD LIMITER; STALL Warning; MACH TRIM and EFIS COMP MON. The crew diverted to the nearby airport for an uneventful landing. Descending through FL200 in VMC partial equipment functionality returned.