What action should be taken after takeoff on dark nights with poor horizon visibility?

After takeoff on dark nights with poor horizon visibility, it is essential to continue relying solely on instruments. This is primarily due to the insufficient visual references available in such conditions, which can lead to disorientation and increase the risk of spatial awareness issues. Instrument flight allows pilots to maintain proper altitude, heading, and control of the aircraft without depending on potentially misleading external cues that may not be visible in low visibility situations.

Utilizing instruments ensures that the pilot is managing the aircraft safely and effectively, especially during the critical phases of flight when maintaining a correct flight path is vital. It emphasizes the importance of instrument proficiency and the ability to navigate and operate the aircraft effectively when visual cues are unreliable or absent, such as during night operations or in weather conditions that limit horizon visibility.

Other options suggest varying degrees of reliance on visual references, which could compromise the safety of the flight given the conditions described. Therefore, the focus on instrument use underscores the best practice for maintaining safety in these circumstances.