Small Aircraft
Flight Crew Instrument; Flight Crew Commercial; Flight Crew Flight Instructor
Flight Crew Last 90 Days 50; Flight Crew Total 550; Flight Crew Type 350
Situational Awareness; Distraction; Training / Qualification
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Overcame Equipment Problem
Procedure; Airspace Structure; Human Factors
Squawked VFR (1200) in the SFRA. Returned to work as flight instructor after being gone for about three months due to closures caused by the COVID-19 Virus. First day back at ZZZ. Flying with XX year old student who tends to skip around checklists (it was his first day back; too); I usually watch him like a hawk because of this tendency. Still; he managed to miss the 'transponder' item and somehow it got past me. Even still; I normally double (sometimes triple) check the transponder as part of my pre-takeoff flow. Because of my extended absence and lack of proficiency in the SFRA; I forgot to double check and took off with 1200 on the transponder. In order to resolve this issue; I need to keep a closer watch on my students; as I am the PIC. Aircraft is based in ZZZ; so transponder should be set to 12XX as its default squawk code. I must be more adamant about checking my transponder before takeoff.
Instructor pilot reported taking off with incorrect transponder code and cited lack of flying due to the COVID-19 as a contributing factor.