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B737 captain reported an IAS disagree warning and erroneous airspeed indications while on the arrival.
| Attributes | |
| ACN | 1519775 |
| Time | |
| Date | 201802 |
| Local Time Of Day | 1201-1800 |
| Place | |
| Locale Reference | ZZZ.Airport |
| State Reference | US |
| Environment | |
| Flight Conditions | IMC |
| Light | Daylight |
| Aircraft 1 | |
| Make Model Name | B737-700 |
| Operating Under FAR Part | Part 121 |
| Flight Phase | Descent |
| Flight Plan | IFR |
| Component | |
| Aircraft Component | Airspeed Indicator |
| Person 1 | |
| Function | Captain Pilot Not Flying |
| Qualification | Flight Crew Instrument Flight Crew Air Transport Pilot (ATP) Flight Crew Multiengine |
| Experience | Flight Crew Last 90 Days 385 Flight Crew Type 12000 |
| Events | |
| Anomaly | Aircraft Equipment Problem Less Severe Deviation - Speed All Types |
Narrative:
During descent on the arrival we noticed an IAS disagree on the captain's display. The first officer was the pilot flying in LNAV/VNAV with the B autopilot on. We received a VNAV disconnect message with the cws (control wheel steering) pitch flashing. The captain's airspeed on the pfd; HUD; and standby airspeed indicator were all erratic and unreliable. Airspeed showed anywhere between 280 and 140 with the buffet alert on the FMC scratchpad. The wind readout on the left inboard du (display unit) showed a wind of 110/188 while the right du readout showed 230/35 which corresponded with the flight plan and forecast winds from the weather packet. We were in IMC conditions from top of descent to 10;000 ft with the engine anti-ice on. We complied with the QRH for IAS disagree which directed us to the airspeed unreliable checklist. We notified ATC we would be unable to fly the airspeeds and altitudes on the arrival and received radar vectors for a visual approach. We continued in VMC conditions and landed uneventfully. Upon arrival; we notified ops; maintenance; and dispatch; and the aircraft was removed from service.
Original NASA ASRS Text
Title: B737 Captain reported an IAS Disagree warning and erroneous airspeed indications while on the arrival.
Narrative: During descent on the arrival we noticed an IAS DISAGREE on the Captain's display. The First Officer was the Pilot Flying in LNAV/VNAV with the B autopilot on. We received a VNAV Disconnect message with the CWS (Control Wheel Steering) Pitch flashing. The Captain's airspeed on the PFD; HUD; and standby airspeed indicator were all erratic and unreliable. Airspeed showed anywhere between 280 and 140 with the Buffet Alert on the FMC scratchpad. The wind readout on the left inboard DU (Display Unit) showed a wind of 110/188 while the right DU readout showed 230/35 which corresponded with the flight plan and forecast winds from the weather packet. We were in IMC conditions from top of descent to 10;000 ft with the engine anti-ice on. We complied with the QRH for IAS DISAGREE which directed us to the AIRSPEED UNRELIABLE checklist. We notified ATC we would be unable to fly the airspeeds and altitudes on the arrival and received radar vectors for a visual approach. We continued in VMC conditions and landed uneventfully. Upon arrival; we notified Ops; Maintenance; and Dispatch; and the aircraft was removed from service.
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.