What is required to discontinue opposite direction vertical separation?

Discontinuing opposite direction vertical separation typically requires both aircraft to report passing NAVAIDs. NAVAIDs help pilots and air traffic controllers identify their positions along the airway, and reports from both aircraft ensure that they are at the correct altitudes and are maintaining safe separation. This verification process allows controllers to confidently manage air traffic and ensure that the aircraft can safely operate at the same or crossing altitudes without the risk of a vertical collision. By confirming the positions using NAVAIDs, it provides an extra level of assurance that altitude and separation standards are being adhered to before lifting the restrictions on vertical spacing.