During a ground check point for an instrument takeoff, the EHSI must be within how many degrees of a known reference point?

The requirement for the EHSI (Electronic Horizontal Situation Indicator) to be within 5 degrees of a known reference point during a ground check for an instrument takeoff is grounded in the need for accuracy in navigational systems. The EHSI plays a crucial role in providing the pilot with essential flight information, including heading and navigational data. Ensuring that the EHSI aligns closely with a known reference point minimizes the risk of navigational errors during takeoff.

Maintaining this 5-degree tolerance ensures that the aircraft's navigational readings are reliable, which is vital for safe instrument flying. Small discrepancies beyond this range could lead to significant navigation errors, especially when flying in reduced visibility or relying solely on instruments. Thus, this standard is in place to promote operational safety and enhance situational awareness for pilots during critical phases of flight, such as takeoff.

The other options suggest wider tolerances, which could compromise accuracy and safety, emphasizing why the standard is set specifically at 5 degrees. This figure reflects an industry consensus on the balance between practical operational limits and the necessity for precision in aviation instrumentation.