Fig. 33-2 GPWS warning indications
The red PULL UP warning lights come on when mode 1, 2,3,or 4 flight path is detected. The amber BELOW G/S warning lights come on when glide slope deviation becomes excessive. Pressing the BELOW G/S lens cap will inhibit this warning. The red WINDSHEAR warning message on the bottom of the EADI is shown whenever windshear conditions are detected.
[3] The purpose of mode 1 is to alert the flight crew to an excessive descent rate with respect to terrain clearance. This mode is independent of landing gear and flap positions. Mode 1 indications occur below 2450 feet radio altitude down to 10 feet when the descent rate exceeds a threshold value as indicated on figure 33-3, The mode 1 envelope is divided into two areas: the initial penetration area and the inner warning area.
Initial penetration of the mode 1 envelope is annunciated by the illumination of the red PULL UP light and the repeated aural message “SINK RATE …”.Penetration of the inner warning area is annunciated by the red PULL UP light and the repeated aural message“WHOOP, WHOOP, PULL UP…”
Fig. 33-3 GPWS- mode 1
[4] The purpose of mode 2 is to alert the flight crew to an excessive closure rate with respect to rising terain. This mode consists of two submodes: If the flaps are 15 units or less and the airplane is not on the glide slope beam, mode 2A is annunciated ; if the flaps are down greater than 15 unit or the airplane is on the glide slope beam and within 2 dots of deviation, mode 2B is annunciated.
[5] The mode 3 is designed to alert the flight crew to an excessive loss of altitude after take off or during a missed approach. Mode 3 provides two types of warnings; Type-1 warning is provided whenever the airplane loses a predetermined amount of inertial altitude on take off or go around and type-2 warning is provided when the airplane does not have sufficient radio altitude. Mode 3 and mode 4 may not be armed at the same time. When one of these modes is armed the other mode is disabled.
[6] The purpose of mode 4 is to alert the flight crew to insufficient terrain clearance when not in landing coufiguration. Mode 4 usually applies during the landing phase of flight .It is armed after take off when the airplane exceeds the mode 3, type-2 upper boundary. Mode 4 consists of two submodes. When the landing gear is up, mode 4A is annunciated. When the landing gear is down, but the flaps are less than or equal to 15 units, mode 4B is annunciated.
[7] The purpose of mode 5 is to alert the flight crew to an excessive deviation below the glide slope when making a front-course approach. Mode 5 is armed when the airplane is below 1000 feet with the gear down. The mode 5 envelope is divided into two alerting areas:the low level (6 db below normal) initial penetration alerting area, and the normal level inner alerting area. The low level alerting area indications occur when the glide slope deviation exceeds 1.3 dots. The normal level alerting area indication occur only below 300 feet radio altitude and down to 30 feet, and when the glide slope deviation exceeds 2.0 dots. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：第31课 大气数据系统 LESSON 31 AIR DATA SYSTEM(12)
