One standard, many airports: Evaluating a uniform ground-time planning parameter for KC-390 airlift operations

Abstract Ground-time allowances link aircraft ground operations to mission feasibility and crew-duty margins, but uniform values can conceal differences between airports. This study evaluates the two-hour allowance used to plan Brazilian Air Force KC-390 airlift missions against 1,679 ground events reconstructed from 2023–2024 mission reports. The standard covers 57% of stops, implying an overrun-to-unused-allowance cost ratio of about 1.3. A two-regime mixture separates routine service from extended ground events and supports a conservative 4.5-h trimming threshold; recorded durations show no anchoring to the planning value. Median and one-sided trimmed-mean models identify three of 14 aerodromes where the standard is systematically too short and only 25–35% of stops meet it. These findings survive Holm correction and empirical Bayes partial pooling. Two further aerodromes warrant monitoring with explicit sample-size rules. Extended-event shares range from 1% to 12%, distinguishing routine shortfalls from tail risks. In mission-level simulations, localized allowances of 2.39–2.47 h reduce the probability of a cumulative overrun above 30 minutes from 66% to 38% on a route through two affected aerodromes. A tiered adjust–monitor–retain policy translates these findings into mission-planning inputs, using an aggregate-data workflow compatible with restricted operational records.