This dataset provides the atmospheric volume mixing ratio of formaldehyde measured during airborne campaigns conducted by NASA's Atmospheric Tomography (ATom) mission. ATom deploys an extensive gas and aerosol payload on the NASA DC-8 aircraft for systematic, global-scale sampling of the atmosphere, profiling continuously from 0.2 to 12 km altitude. Flights occurred in each of 4 seasons from 2016 to 2018. The NASA In Situ Airborne Formaldehyde (ISAF) instrument, based at the Goddard Space Flight Center, measures formaldehyde on high-altitude NASA aircraft. The instrument uses laser-induced fluorescence (LIF) to obtain the high detection sensitivity needed to detect formaldehyde in the upper troposphere and lower stratosphere where abundances are 10 parts per trillion. LIF also enables a fast time response needed to measure the abundance of formaldehyde in the finely structured outflow of convective storms. These measurements of formaldehyde will be used elucidate mechanisms of convective transport and quantify the effects of boundary layer pollutants on the ozone photochemistry and cloud microphysics of the upper atmosphere.