Cross country ( xc ) - an advanced skill where pilots take advantage of air currents to cover the greatest distance possible over the ground 越野飞行飞行者在空中掌握气流状况优势的先进技术，去突破地表上横跨最远距离的可能。
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The study commenced in october 2003 to explore the feasibility of establishing some protocols to assess the effects of major planning and development proposals on external air movement for the achievement of enhanced macro wind environment 二零零三年十月，本署展开研究，探讨可否设立若干规程，以评估大型规划和发展建议对户外空气流通情况的影响，从而改善整体环境的气流状况。
