Question 68 FCP01 - First Class Pilot

The Correct Answer is B ### Explanation of Correctness (Option B) **1. Understanding Gyrocompass Error:** Gyrocompass error is defined as the difference between the True Heading (TH) and the Gyro Heading (GH). $$\text{Error} = \text{TH} - \text{GH}$$ The error is named for the direction of the True Meridian relative to the reading shown by the Gyrocompass. If the error is **East (E)**, it means the gyro reading (GH) is to the East (clockwise) of the True Heading (TH) when viewed from the direction of travel, or, more commonly used in navigation, it means the True Meridian is East of the Gyro North. When the error is East: * The Gyro North pole is displaced to the West of True North. * The gyrocompass reading (GH) is numerically **smaller** than the True Heading (TH). **Example:** If True North is 000°, and the gyro error is 5° East, the gyrocompass is indicating 355° for True North (or, if sailing $090^\circ$ True, the gyro reads $085^\circ$). **2. Determining the Correction:** To obtain the True Heading (TH) from the Gyro Heading (GH), you must apply the correction (the amount of the error). Since the Gyro Heading (GH) is too small (low numerically) when the error is East, the amount of the error must be **added** to the Gyro Heading to obtain the True Heading: $$\text{TH} = \text{GH} + \text{Error (when Error is East)}$$ Therefore, the readings are too low (small numerically) and the amount of the error must be added to the compass to obtain true. *** ### Explanation of Incorrect Options **A) The readings are too high (large numerically) and the amount of the error must be added to the compass to obtain true** * **Incorrect:** If the error is East, the readings are **too low**, not too high. If the readings were too high, the error would be West. **C) The readings are too low and the amount of the error must be subtracted from the compass to obtain true** * **Incorrect:** While the readings are correctly identified as being too low when the error is East, subtraction is the wrong mathematical operation. If the reading is too low, you must **add** the correction to increase the numerical value to reach the true heading. Subtraction would result in an even smaller, incorrect value. **D) The readings are too high and the amount of the error must be subtracted from the compass to obtain true** * **Incorrect:** This describes the scenario where the error is **West**. If the error were West, the gyro reading would be too high, and you would subtract the error to get True. It does not describe an East error.