What happens to engine performance as altitude increases?

As altitude increases, the performance of a turbine engine is affected primarily due to the decrease in air density. This change in density leads to less available oxygen for combustion. As a result, if no compensating actions are taken, the overall performance of the engine may decrease, particularly in terms of thrust output.

In turbine engines, performance at high altitudes typically shows a decline in specific power output because of this reduced oxygen supply, which adversely affects the combustion process. Turbine engines may require adjustments, such as increasing fuel flow or utilizing variable inlet guide vanes, to maintain efficiency and thrust. Recognizing the need for these compensations is crucial for pilots and engineers to ensure safe and optimal operation of the engine at higher altitudes.

The other options imply that the engine performance improves or remains unaffected at higher altitudes, which does not accurately reflect the dynamics involved in how turbine engines operate in thinner air.