+#define BOOST_TICKS_MAX AO_SEC_TO_TICKS(15)
+
+/* This value is scaled in a weird way. It's a running total of accelerometer
+ * readings minus the ground accelerometer reading. That means it measures
+ * velocity, and quite accurately too. As it gets updated 100 times a second,
+ * it's scaled by 100
+ */
+__data int32_t ao_flight_vel;
+
+/* convert m/s to velocity count */
+#define VEL_MPS_TO_COUNT(mps) ((int32_t) ((int32_t) (mps) * (int32_t) 100 / (int32_t) ACCEL_G))