figure following MDA which, when added to the airport     是MDA后括号内的数值，它与机场标高相加后即是

elevation, will give the MDA in feet above mean sea     MDA高于平均海平面的英尺数。只有当接地区跑道顶端或

level. A HAA will follow a DA or DH only when there is  跑道头标高不可得时，机场上空高度才跟着决断高度（DA

no touchdown zone, runway end, or threshold elevation   或DH）．

available.

HEIGHT ABOVE TOUCHDOWN (HAT), IS the                    离接地点高度（HAT），

parenthetical figure following DH, DA or MDA which,       决断高度或最低下降高度后括号中的数值。它与接地

when added to the touchdown zone, runway end, or        区、跑道顶端、或跑道头标高相加后即是决断高度（DA，

threshold elevation, will give the DH, DA or MDA in feet DH）或最低下降高度（MDA）高于平均海平面英尺数。

above mean sea level. HAT is published in conjunction   接地高度是与直接进场着陆的最低天气条件同时公布的。

with straight-in minimums.

HERTZ (Hz), The standard radio equivalent of            赫兹（HZ），

frequency in cycles per second of an electromagnetic      单位是周期/秒的电磁波频率的标准射电当量。一千赫

wave. One Kilohertz (kHz) is a frequency of one         兹是每秒一千周期的频率。一兆赫是每秒一百万周期的

thousand cycles per second. One Megahertz (MHz) is a    频率。

frequency of one million cycles per second.

HEXADECIMAL NUMBERING SYSTEM, A numbering               十六进制编号系统，

system with sixteen as the base. The system includes      一种以16为底数的编号系统。该系统包括由数字0至

digits zero through nine, and letters A through F       9，字母A至F代表10至15．

representing the numbers ten through fifteen.

HIGH FREQUENCY (HF), The frequency band between         高频（HF），

3 and 30 MHz.                                             频率带在3至30兆赫之间。

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HIGH SPEED TAXIWAY/EXIT/TURNOFF (HST), A long            高速滑行道／出口（HST），

radius taxiway designed and provided with lighting or      是一条半径大的滑行道。该滑行道有灯光和标志表明飞

marking to define the path of aircraft, traveling at high 机从跑道中心到滑行道中心一点高速（可大到60海里）通

speed (up to 60 knots), from the runway center to a      过的路径。也被称为大半径出口或脱离道。高速滑行道的