The analysis of 140 dual flights between two types of ozonesondes, namely, the Brewer-Mast (BM) and the electrochemical concentration cell (ECC), is presented in this study. These dual flights were performed before the transition from BM to ECC as the operational ozonesonde for the Payerne Aerological Station, Switzerland. The different factors of the ozonesonde data processing are considered and their influences on the profile of the difference are evaluated. The analysis of the ozone difference between the BM and the ECC ozonesonde data shows good agreement between the two sonde types. The profile of the ozone difference is limited to ±5% (±0.3 mPa) from the ground to 32 km. The analysis confirms the appropriateness of the standard BM data processing method and the usefulness of the normalization of the ozonesonde data. The conclusions of the extended dual flight campaigns are corroborated by the analysis of the time series of the Payerne soundings for the periods of 5 years before and after the change from BM to ECC which occurred in September 2002. No significant discontinuity can be identified in 2002 attributable to the change of sonde.