Who benefits from Urban Air Mobility? Spatial and income equity in multi-phased vertiport deployment

Phased deployment of Urban Air Mobility (UAM) vertiport produces distributional effects that static, end-state assessments miss. How accessibility gains evolve across construction phases and population groups has not been studied systematically. This study investigates three questions for the phased vertiport siting problem: how equity trajectories change from phase to phase, whether spatial equity at the zonal level and income-based equity at the individual level move in tandem, and whether conventional interventions such as fare reductions and construction subsidies produce their intended distributional effects. Applying a two-dimensional equity framework that pairs the Gini coefficient with the Concentration Index, we analyze a multi-phased vertiport deployment in the Munich Metropolitan Area under three policy scenarios, complemented by sensitivity analyses on network scale and subsidy depth. Three principal findings emerge. First, spatial and income-based equity are decoupled: the scenario with broadest spatial coverage exhibits pro-rich income distributions across all construction phases. Second, income-based equity trajectories converge toward pro-rich configurations by the final phase across all scenarios despite different starting points. Third, fare reductions intensify income inequality by increasing trip frequency among already-served upper-middle income households rather than expanding the beneficiary pool, while construction subsidies reduce inequality by redirecting vertiport sites toward middle-income populations. Sensitivity analyses show network expansion can approach income-neutrality with diminishing returns, and subsidy effectiveness varies between spatial and income dimensions. These findings demonstrate that equity-conscious UAM planning requires multi-dimensional assessment and supply-side interventions rather than demand-side pricing policy.