Steering by automatic pilot and by magnetic compass in stead of automatic pilot measure the exactness of magnetic compass by qualified calibrator and provide compass adjustment card.
自动驾驶仪操舵和用磁罗经代替自动驾驶仪，通过合格的校准器来测定罗经的正确功能并提供罗经校正卡。
2
The compass is very essential for us to travel in the forests. without ti, we may get lost. in a word, among all above, I think the ID card is the most important.