Before an aircraft enters the Terminal Manoeuvring Area (TMA) a delay may need to be introduced due to capacity limits. An Air Traffic Controller (ATCo) has the opportunity to introduce a holding procedure. When multiple aircraft need to be delayed in this form a holding stack may be formed. This holding stack is formed above the Initial Approach Fix (IAF). Current industry standard is able to achieve an accuracy within two minutes of planned Estimated Approach Time (EAT), at which the aircraft is planned to fly over the IAF and proceed to the TMA. In this research a display tool to aid Area Controllers (ACC) in realising a more accurate delivery and improving their situational awareness is designed, called the Stack Planner (SP). The SP assists controllers with choosing an optimal holding leg time for aircraft in the holding stack to adjust their IAF flyover time. The display aims to assist ATCo by showing the possible space of their control actions as well as system constraints. In an initial proof-of-concept experiment, comparing the SP display with a baseline state of the art display, promising results are found; the SP display shows a more manageable workload with increased situational awareness that scales with scenario complexity. The new display also shows the potential to move from minute accuracy to second accuracy. Future studies would need to investigate the extent to which scenario complexity plays a role in accuracy of delivery for both baseline and SP displays.