B737-800
Flight Crew Air Transport Pilot (ATP); Flight Crew Instrument; Flight Crew Multiengine
Confusion; Training / Qualification
Deviation - Speed All Types; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Human Factors
ZZZ Tower told us to go-around due to the aircraft landing in front of us not clearing the runway. On go-around I inadvertently pressed the autothrottle disconnect switch instead of the go-around switch. As I rotated and began the go-around litany; my First Officer stated 'Airspeed.' I had not added enough power during clean-up and our airspeed got below Vref.I am new to the 737; just reaching the 100-hour consolidation period last week. It has taken me over 3 1/2 months to accumulate the 100 hours. I am very junior on the aircraft so I am on reserve and have not flown very often. I transitioned from the MD80 which I have flown for over 11 years straight. On the go-around; I was having trouble locating the go-around switch on the throttles because my old habit pattern kicked in and I was searching for the switch where it used to be on the MD80. I then mistakenly pressed the auto throttle disconnect switch and initially did not added enough power for the go-around.I have to mentally practice the go-around procedure; including all of the physical movements I would be making during the go-around so that my hand can reflexively find the go-around switch instead of reverting to old 'muscle memory'.
B737 Captain reported that unfamiliarity with a new aircraft caused them to inadvertently disconnect the autothrottle during a go-around.