+extern __pdata int16_t ao_ground_height;
+extern __pdata int16_t ao_max_height;
+extern __pdata int16_t ao_height; /* meters */
+extern __pdata int16_t ao_speed; /* m/s * 16 */
+extern __pdata int16_t ao_accel; /* m/s² * 16 */
+
+#define AO_M_TO_HEIGHT(m) ((int16_t) (m))
+#define AO_MS_TO_SPEED(ms) ((int16_t) ((ms) * 16))
+#define AO_MSS_TO_ACCEL(mss) ((int16_t) ((mss) * 16))