What is a major drawback of accelerometer-based altimeters?

Accelerometer-based altimeters primarily rely on the measurement of acceleration to determine altitude, which involves integrating the acceleration data over time. A significant drawback is that for these altimeters to provide accurate altitude readings, the flight must be nearly vertical. If the rocket veers off from a vertical path, the acceleration readings can become complicated and lead to incorrect calculations of altitude. In a non-vertical flight, the accelerometer may pick up lateral accelerations that distort altitude measurements.

In contrast, accelerometers may still provide some readings in various conditions, but the reliance on a perfect vertical trajectory highlights the limitations of this technology for accurate altitude measurement. Therefore, while other options may present challenges, the need for a perfect vertical flight is a fundamental issue that affects the reliability of accelerometer-based altitude readings.