This technical report presents the OAG Frequency and Capacity Statistics for June 2021, detailing global seat capacity trends compared to June 2019 levels. The report outlines significant increases in capacity across various regions, with global capacity reaching 37.3% below 2019 levels. Europe shows a notable recovery with 21.4 million additional seats, while North America adds 8.4 million seats, indicating a positive trend in the domestic market. Conversely, Asia experiences a reduction of 3.6 million seats due to ongoing COVID-19 outbreaks. The report also highlights the top twenty country pairs with increased capacity, including Spain-UK and Russia-Ukraine, and discusses the performance of major airlines and airports. American Airlines and Southwest Airlines lead in domestic frequency recovery, while Chinese airlines face reductions. The report concludes with insights into the ongoing impacts of COVID-19 on global air travel capacity and frequency.