figure following MDA which, when added to the airport     是MDA后括號內的數值，它與機場標高相加后即是

elevation, will give the MDA in feet above mean sea     MDA高于平均海平面的英尺數。只有當接地區跑道頂端或

level. A HAA will follow a DA or DH only when there is  跑道頭標高不可得時，機場上空高度才跟著決斷高度（DA

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

available.

HEIGHT ABOVE TOUCHDOWN (HAT), IS the                    離接地點高度（HAT），

parenthetical figure following DH, DA or MDA which,       決斷高度或最低下降高度后括號中的數值。它與接地

when added to the touchdown zone, runway end, or        區、跑道頂端、或跑道頭標高相加后即是決斷高度（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數。

above mean sea level. HAT is published in conjunction   接地高度是與直接進場著陸的最低天氣條件同時公布的。

with straight-in minimums.

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

frequency in cycles per second of an electromagnetic      單位是周期/秒的電磁波頻率的標準射電當量。一千赫

wave. One Kilohertz (kHz) is a frequency of one         茲是每秒一千周期的頻率。一兆赫是每秒一百萬周期的

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

frequency of one million cycles per second.

HEXADECIMAL NUMBERING SYSTEM, A numbering               十六進制編號系統，

system with sixteen as the base. The system includes      一種以16為底數的編號系統。該系統包括由數字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         高頻（HF），

3 and 30 MHz.                                             頻率帶在3至30兆赫之間。

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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      是一條半徑大的滑行道。該滑行道有燈光和標志表明飛

marking to define the path of aircraft, traveling at high 機從跑道中心到滑行道中心一點高速（可大到60海里）通

speed (up to 60 knots), from the runway center to a      過的路徑。也被稱為大半徑出口或脫離道。高速滑行道的