If I understand your question correctly this correction is necessary if you need to find the direction of the geographic north (or south), which is usually different from the magnetic north. There is a tilt of approximately $11^O$ between the two. As of 2010, the magnetic north was located at approximately 80.08°N 72.21°W, on Ellesmere Island. One way to find the direction of the geographic north on the surface of the Earth is if you know the direction of the magnetic field and if you know the direction of the center of the Earth, which you can find with the accelerometers, and if you know the geographical position of the magnetic north (this is important). I would imagine that the measurements of $\vec{B}$ and $\vec{g}$ would have to be very precise to get a good correction. If you had your (lat, lon) location from GPS this could substitute the need for the accelerometers, that's correct. But you would still need $\vec{B}$ and the geographical position of the magnetic north.

To answer your questions, as you go to higher latitudes this correction can become more important, depending on the longitude. But even at the equator, depending again on the longitude, your corrections could be significant, since the magnetic north has a westward component.

If I understand your question correctly this correction is necessary if you need to find the direction of the geographic north (or south), which is usually different from the magnetic north. There is a tilt of approximately $11^O$ between the two. As of 2010, the magnetic north was located at approximately 80.08°N 72.21°W, on Ellesmere Island. One way to find the direction of the geographic north on the surface of the Earth is if you know the direction of the magnetic field and if you know the direction of the center of the Earth, which you can find with the accelerometers, and if you know the geographical position of the magnetic north (this is important). I would imagine that the measurements of $\vec{B}$ and $\vec{g}$ would have to be very precise to get a good correction. If you had your (lat, lon) location from GPS this could substitute the need for the accelerometers, that's correct. But you would still need $\vec{B}$ and the geographical position of the magnetic north.

To answer your questions, as you go to higher latitudes this correction can become more important, depending on the longitude. But even at the equator, depending again on the longitude, your corrections could be significant, since the magnetic north has a westward component.

If I understand you question correctly this correction is necessary if you need to find the direction of the geographic north (or south), which is usually different from the magnetic north. There is a tilt of approximately $11^O$ between the two. As of 2010, the magnetic north was located at approximately 80.08°N 72.21°W, on Ellesmere Island. One way to find the direction of the geographic north on the surface of the Earth is if you know the direction of the magnetic field and if you know the direction of the center of the Earth, which you can find with the accelerometers, and if you know the geographical position of the magnetic north (this is important). I would imagine that the measurements of $\vec{B}$ and $\vec{g}$ would have to be very precise to get a good correction. If you had your (lat, lon) location from GPS this could substitute the need for the accelerometers, that's correct. But you would still need $\vec{B}$ and the geographical position of the magnetic north.

To answer your questions, as you go to higher latitudes this correction can become more important, depending on the longitude. But even at the equator, depending again on the longitude, your corrections could be significant, since the magnetic north has a westward component.

If I understand your question correctly this correction is necessary if you need to find the direction of the geographic north (or south), which is usually different from the magnetic north. There is a tilt of approximately $11^O$ between the two. As of 2010, the magnetic north was located at approximately 80.08°N 72.21°W, on Ellesmere Island. One way to find the direction of the geographic north on the surface of the Earth is if you know the direction of the magnetic field and if you know the direction of the center of the Earth, which you can find with the accelerometers, and if you know the geographical position of the magnetic north (this is important). I would imagine that the measurements of $\vec{B}$ and $\vec{g}$ would have to be very precise to get a good correction. If you had your (lat, lon) location from GPS this could substitute the need for the accelerometers, that's correct. But you would still need $\vec{B}$ and the geographical position of the magnetic north.

To answer your questions, as you go to higher latitudes this correction can become more important, depending on the longitude. But even at the equator, depending again on the longitude, your corrections could be significant, since the magnetic north has a westward component.