What is the accuracy of GPS in terminal and departure phases?

The accuracy of GPS during the terminal and departure phases is indeed 1 nautical mile. This figure represents the horizontal accuracy that can be expected from GPS technology in these operational phases. During terminal and departure phases, aircraft are typically operating at lower altitudes and in more congested airspace, where precision is vital for maintaining safe separation from other aircraft and ensuring adherence to prescribed flight paths.

The 1 nautical mile accuracy reflects the high performance of GPS in providing reliable navigation data that supports safe operations in the terminal environment. This is particularly critical as aircraft approach airports for landing or during takeoff, where precise navigation can enhance safety and efficiency.

When comparing this accuracy to the other options, 0.3 nautical miles represents a level of precision that is not typically achievable with conventional GPS under standard conditions. Options of 2 and 3 nautical miles would imply a broader margin of error that is not suitable for the critical phases of flight associated with terminal area navigation, where tighter standards are required. Therefore, the 1 nautical mile standard aligns with the operational needs and technical capabilities of GPS in these specific flight stages.