horizontal earth rate

horizontal earth rate

[‚här·ə′zänt·əl ′ərth ‚rāt]
(navigation)
The rate at which the spin axis of a gyroscope must be tilted about the horizontal axis to remain parallel to the earth's surface to compensate for the effect of earth rate; horizontal earth rate is maximum at the equator, zero at the poles, and varies as the cosine of the latitude.