Far more successful was the land based Lockheed EC-121 Warning Star, which was introduced in 1954 in both Air Force and Navy service as pickets and in other roles. As pickets the Air Force EC-121s provided radar coverage by flying "Contiguous Barrier" orbits 300 miles offshore, between the coasts and the AGR Guardian picket lines. The Navy version (designated WV-2 before 1962) flew over the more distant BarLant and BarPac DER lines. Their main deficiency was lack of endurance, which made them unsuitable for naval fleet coverage.