Date: 201811
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Aircraft: B737 Undifferentiated or Other Model
Operator: Air Carrier
Operating under: Part 121
Flight plan: IFR
Mission: Passenger
Flight phase: Cruise
Aircraft component: Airspeed Indicator
Component problem: Malfunctioning
Reporter organization: Air Carrier
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Multiengine; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Confusion; Workload; Troubleshooting; Distraction
Second reporter function: First Officer; Pilot Not Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation - Speed All Types
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Overcame Equipment Problem; General Maintenance Action
Contributing factors: Aircraft
Primary problem: Aircraft

Narrative: The flight proceeded normally until approximately 10 minutes prior to descent at FL280.The first indication of a problem was an 'IAS DISAGREE' message on both pilots' primary displays. We compared the three airspeed readings and found that the Captain and STBY readings agreed while mine (FO (First Officer)) was showing ~5 knots slow. I pulled out the QRH and turned to the 'IAS DISAGREE' page which referred us to the 'AIRSPEED UNRELIABLE' checklist. By the time I had reached that checklist; the 'IAS DISAGREE' message was gone and the airspeed indicators were within 4 knots of each other. Both pilots then reviewed the 'AIRSPEED UNRELIABLE' checklist for familiarization.Several minutes later the 'IAS DISAGREE' message returned; and we returned to the QRH. After only a few steps of the checklist had been accomplished we received a Master Caution with [ENG] light on the right RECALL panel and found that both EEC switches (aft-overhead panel) were showing 'ALTN'. The Captain decided to suspend the 'AIRSPEED UNRELIABLE' checklist; as his and the STBY airspeed indications were stable; and go to the QRH checklist for the EEC 'ALTN' lights.The Captain (PF; Pilot Flying) took the radios as I actioned the 'EEC ALTERNATE MODE' checklist. The 'DSPLY SOURCE' annunciation was not shown and the checklist was completed on that step.We returned to the 'AIRSPEED UNRELIABLE' checklist. By this time we were in the descent and the FO airspeed indication had dropped to the mid-100 knot range with the Capt and STBY indication ~280kts. The 'ALT DISAGREE' message also appeared on the altimeter displays on both pilot's primary displays. The FO altitude was reading between 100 feet and 400 feet HIGHER than the Capt and STBY altitude display for the remainder of the flight. During the descent; the FO airspeed indication dropped to 45 knots and remained there for the remainder of the flight.On the 'AIRSPEED UNRELIABLE' checklist; we followed the '...can be determined' option; 'Capt or FO airspeed indication is reliable' option; and 'Altitude is reliable' option which resulted in the end of the procedure.We next accomplished the 'ALT DISAGREE' checklist. We followed the '...stays illuminated' option and the '...can be determined' option.Weather conditions for descent and landing were clear; night; VMC. There was no visible moisture to suggest icing and we verified that the Probe Heat was on; all probe heat annunciators were off and working (bulb test). We conducted a visual approach to ZZZ Rwy XXL backed up by the ILS XXL in the VHF and FMS. The Captain hand-flew the approach with the auto-thrust off. Both pilots ignored the FO flight instrument airspeed and altitude readings and used the data from the Capt's instruments verified against the standby instruments for the approach and landing.This was the Captain's leg so the FD was mastered on his side and only Autopilot A was used. The transponder and Mode C were both selected to '1'. There were no abnormal or invalid FD commands nor AP control inputs at any time during the flight. ZZZ is a contract maintenance station. [Maintenance Control] requested us to remain to perform an engine run (both engines). With [Management] approval; and [Maintenance Control] instructions; we ran both engines for 11 minutes while the contract mechanic reset the EECs and verified that they operated normally.


Second narrative: [Report narrative contained no additional information.]


Synopsis: B737 flight crew reported several spurious instrument indications related to airspeed; altitude; and engine control.