ADV

The provided articles do not mention any organization called "ADV." Instead, they focus on two distinct issues within the German aviation sector. The first article reports on an impending strike by Lufthansa flight attendants, potentially leading to numerous flight cancellations on the last day of the Easter holidays. Lufthansa is attempting to mitigate the impact by scheduling additional flights. The second article discusses the German government's decision to lower the air travel tax, aiming to reduce revenue to 2024 levels, fulfilling a coalition agreement promise. While this tax reduction might seem beneficial, the article suggests that travelers shouldn't expect significantly cheaper flights as a result. Therefore, neither article provides any information about an organization named ADV, making it impossible to summarize its activities or relevance based on the given text.