B737 Pilots reported receiving an airspeed unreliable notification on takeoff and returned to the departure airport.
Synopsis
B737 Pilots reported receiving an airspeed unreliable notification on takeoff and returned to the departure airport.
Narrative
On takeoff out of ZZZ; at 80 knots; we had an airspeed differential; Captain side low. F/O (First Officer) and Standby airspeed indicated normally. Shortly after; got an ENG light on the annunciator panel. Continued takeoff. Once airborne; received airspeed disagree indication along with intermittent altitude disagree indications on both displays. Referenced QRC; Airspeed Unreliable. Once complete; referenced QRH (Quick Reference Handbook) Airspeed Unreliable. We determined that the Standby and First Officer instruments were working properly. After assessing situation; decided to return to ZZZ. Notified Passengers. Notified Dispatch; coordinated air return to ZZZ. Once all QRH steps completed; coordinated for approach to ZZZ. On final; flap indication of 25 disagreed with 30 selected. Initiated go-around. On go-round selected flaps 15; per normal procedure. Left the flaps at 15 for subsequent flight; while further assessing the situation. Coordinated for vectors. Ran QRH Trailing Edge Flap Disagreed Checklist. Computed performance numbers for flaps 15 landing. Completed QRH Checklist. Landed normally with flaps 15 at ZZZ Runway XXL. Following an uneventful landing; ran performance and weights and balance; brake cooling numbers. Two minute cooling required. Accomplished. Taxi normally to gate.
Second reporter narrative
It was my leg from ZZZ to ZZZ1. On takeoff roll at approximately 80 knots; the Master Caution and 'ENG' annunciator light illuminated. The Captain called airspeed unreliable and elected to continue the takeoff. Once airborne; we received a constant Airspeed Unreliable message and intermittent Altitude Unreliable message on the PFDs (Primary Flight Display). I completed the QRC 'Airspeed Unreliable' Checklist memory items while we continued normal departure procedures. The Captain advised ATC of our situation and we were given vectors while we handled the malfunction. After completing the QRC Checklist and referencing the QRH (Quick Reference Handbook); we quickly determined the F/O and Standby indicators were providing correct airspeed and altitude information. The Captain stated his airspeed indicated low during takeoff roll and then indicated high while airborne (varying up to approximately 140 knots high). Due to the nature of the malfunction; the Captain elected to return to ZZZ. After completing all briefs and the QRH 'Airspeed Unreliable' Checklist; we were cleared for a visual XXL approach. When selecting the flaps to 30 for landing; the flap indicator stopped at 25. I initiated a standard go-around except leaving the flaps at 15 since that appeared to be reliable indication and a know configuration setting for landing. After completing the QRH 'Trailing Edge Flap Disagree' Checklist and brief items; we conducted an uneventful flap 15 visual approach and landing to Runway XXL. After clearing the runway; brake cooling did not require a gate holdout; so we proceeded to the gate.
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Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.