What is a significant requirement for IFR operations?

For IFR (Instrument Flight Rules) operations, a crucial requirement is that pilots must file an IFR flight plan and adhere to Air Traffic Control (ATC) instructions. This requirement is in place to ensure organized and safe management of air traffic, especially in conditions that necessitate instrument guidance, such as low visibility or inclement weather.

Filing an IFR flight plan alerts ATC to the flight's route and expectations, allowing for effective tracking and assistance. Adhering to ATC instructions is vital because it ensures that pilots maintain safe separation from other aircraft and comply with all necessary regulations throughout their flight. This process is essential for efficient traffic flow in crowded airspace and enhances safety during IFR operations.

The other options do not reflect the core requirements of IFR operations. For example, while maintaining an appropriate altitude is important, there is no fixed minimum altitude of 3,000 feet applicable to all IFR flights, as this may vary based on airspace class and terrain. Additionally, increasing speed in poor weather conditions is not a standard requirement; rather, pilots are encouraged to maintain control and manage their speed according to the performance of the aircraft and the specific situation. Lastly, using visual flight rules (VFR) in controlled airspace contradicts the principles of