B737 flight crew reported the First Officer's airspeed indicator was unreliable and a diversion was necessary.
Synopsis
B737 flight crew reported the First Officer's airspeed indicator was unreliable and a diversion was necessary.
Narrative
Report menu will not let me choose hours awake before event and hours on duty before event. Actual times are 4 hours awake and 3 hours on duty. Flight was normal all the way up to and including cruise at FL 340. Upon climbing out of cruise from FL340 to FL 360; the First Officer (FO) airspeed indicator started increasing and the IAS disagree annunciation appeared on both ADI's. Moments later the alt disagree annunciator appeared on both ADI's; as well. The FO airspeed was approaching Mach limit and the over speed clacker annunciated. Initial action Quick Reference Checklist (QRC) items were completed and it was determined that the Captain (CA) airspeed and altitude information was correct and matched the standby instruments. Manual pitch and power settings for flaps up were also used to confirm the reliability of the operating CA airspeed and altimeter. The Quick Reference Handbook (QRH) checklist for airspeed unreliable was executed and all steps complied with. Aircraft was no longer RVSM compliant and ATC directed a decent to FL 280. This put our fuel status in a state that would no longer reach our scheduled destination of ZZZ1. The CA contacted Maintenance and there was no available solution to remedy the aircraft status. After working with dispatch; ZZZ2 was determined to be the best divert location. At that time we requested priority and requested routing to ZZZ2. After setting up for the arrival and approach into ZZZ2 for XXL; we started to descend from FL280. During the descent; the FO airspeed began rapidly decreasing to the point where the FO airspeed was bottomed out at 45 kts passing FL180 while the CA airspeed read 250. While the aircraft entered the stall warning red zone; the stick shaker did NOT activate. Overweight landing checklist was also ran. After descending through approximately 13000 ft.; the FO airspeed and altimeter readings appeared to revert back to normal and match the CA's and standby readings. Landing and taxi to park were uneventful. Also on descent during the recall check; the FO noticed an engine warning and both EEC's were in alternate mode. Checklists were ran for that condition and the engines operated in alternate mode for the rest of the flight. Alternate mode was not displayed after engine shut down.
Second reporter narrative
While in a step climb from FL340-360 we received an Airspeed Disagree message. We complied with the immediate action items; and the Altitude Disagree message closely followed. I noticed the First Officer's (F/O's) airspeed was increasing and approaching the redline. My airspeed and altitude appeared accurate; and after running the Quick Reference Checklist (QRC)/ (QRH) Quick reference Handbook; we determined my side was accurate. We informed ATC that we were no longer RVSM capable and they told us to descend to FL280. After conferring with Dispatch and Maintenance we determined a diversion to ZZZ2 would be the most prudent option. We [requested priority landing] and requested routing to ZZZ2. We knew we would have to land overweight so we consulted that non-normal procedure also. We noticed that the F/O'S airspeed indicator was increasing if we climbed and decreased when we descended. At redline the high speed warning came on. During descent the airspeed decrease all the way down to 45 KIAS. Fortunately the stick shaker never came on so there was one less distraction. We accomplished a normal descent; visual approach and landing. We had a normal taxi into the gate. During the descent at around 13000msl; the F/O's instruments started reading normal and the warnings went away. This was my F/O's very first leg of OE. It was quite the welcome to [the company] but he performed very well.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.