Which statement about quadrantal errors is true?

Which statement about quadrantal errors is true?

• A. They are caused by ground reflections only
• B. They are eliminated by turning off the transmitter
• C. They occur at high altitudes only
• D. They cause bearing indicator errors, maximized when RF signals cross the wings or stabilizers

Answer: (D)

Quadrantal errors come from the aircraft itself. The ADF uses a loop-type directional receiver, and the metal airframe—the wings, stabilizers, fuselage—distorts the received radio field. That distortion changes with the direction from which the signal arrives, creating a bearing error that depends on which quadrant the signal is in relative to the aircraft. The effect is strongest when the incoming RF signal lies in the plane of the wings or stabilizers, because the aircraft’s conducting surfaces interact most with the loop pattern in those orientations. So the bearing indication is biased most when the signal crosses the wings or tail, which is exactly why this statement is true. Ground reflections, turning off the transmitter, or the signal only at high altitude don’t define quadrantal error in the way described.

Quadrantal errors come from the aircraft itself. The ADF uses a loop-type directional receiver, and the metal airframe—the wings, stabilizers, fuselage—distorts the received radio field. That distortion changes with the direction from which the signal arrives, creating a bearing error that depends on which quadrant the signal is in relative to the aircraft. The effect is strongest when the incoming RF signal lies in the plane of the wings or stabilizers, because the aircraft’s conducting surfaces interact most with the loop pattern in those orientations. So the bearing indication is biased most when the signal crosses the wings or tail, which is exactly why this statement is true. Ground reflections, turning off the transmitter, or the signal only at high altitude don’t define quadrantal error in the way described.