Which of the following is considered a disadvantage of buying an aircraft?

Purchasing an aircraft comes with significant financial implications that can be considered a disadvantage. Investment and finance requirements entail the need for capital to buy the aircraft outright or secure financing, leading to a large upfront expenditure or ongoing debt obligations. This financial burden can strain cash flow, especially for businesses that may need to allocate funds for other operational needs.

In contrast, the other options depict situations that do not negatively impact the purchasing decision. For instance, having no residual value risk would imply that the aircraft owner does not have to worry about the aircraft's value decreasing over time, which is typically advantageous. Reduced taxes could arise from ownership due to possible depreciation deductions, and less operational costs could be a benefit associated with owned assets, particularly if a company optimizes its usage. Hence, the capital-intensive nature and financial commitments associated with buying an aircraft are surely substantial disadvantages, making investment and finance requirements the correct choice.