B737 Undifferentiated or Other Model
Flight Crew Last 90 Days 180; Flight Crew Total 8000; Flight Crew Type 2000
Distraction; Human-Machine Interface
Deviation - Speed All Types; Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy
Aircraft; Human Factors
After takeoff and on climb from Runway 28R at EE; PF made normal rotation (6.1 pitch) and callouts. After 'Flaps 1' callout and retraction; PM changed from tower to Departure Control frequency; then was told we were on the wrong frequency and were queried as to whether tower had assigned the frequency or we had selected it from the plate. Then GPWS annunciated 'Airspeed Low' as the airspeed had slowed to the top of the amber band and VNAV had apparently disengaged; although it had been selected before takeoff. PF corrected with additional thrust; reselected VNAV; and called for 'Flaps Up' on schedule. Better monitoring of FMA modes [could have prevented this event].
Due to uncertain circumstances the flight crew of a B737 received an airspeed low warning during takeoff and configuration cleanup.  Failure to select and/or remain engaged in VNAV was cited as a possible cause.