[8] Windshear is a phenomenon which can happen anywhere within the atmosphere. It can have both horizontal and vertical components, and involves large volumes of air which move rapidly in different directions (usually opposite). One type of windshear which is most threatening to pilots in the microburst, which produces a column of downward-moving air. Microbursts are most threatening below 500 feet, where pilots have little time and airspace for recovery. Figure 33-4 shows two microburst situations, one in takeoff and the other on approach, with the appropriate explanalions. When the GPWS determines that windshear conditions exist, the aural warning “WINDSHEAR”is repeated and the red windshear warning is displayed on both EADIs.
Fig 33-4 Windshear
A summary of all GPWS mode annunciations is shown on this table.
READING MATERIAL
QUETIONS TO LESSON 33 READING MATERIAL
1. What is the purpose of GPWS mode 5 ?
2. When is mode 5 armed ?
3. The mode 5 envelope is divided into 2 alerting areas, what are they ?
4. When does the low level alerting area indications occur ?
5. When does the normal level alerting area indications occur ?
6. How is mode 5 annunciated ?
7. When is the “GLIDE SLOPE”message repeated more rapidly ?
8. What may be inhibited or cancelled by pressing the G/S P-INHIBIT
light /switch?
9. If the G/S P-INHIBIT light/switch is pressed before the mode 9
indication have started, what will happen?
10. If the G/S P-INHIBIT light /switch is pressed after the mode 9
indication have started, what will happen?
11. When is mode 5 automatically rearmed ?
12. How many aural message are there? what ary they?
EXERCISE
A. Find out the explanations of the following words in your“English-chinese technical dictionary”
1. Go- around (GA) [ P1-70 ]
2. Windshear [ P1-171 ]
3. misssed approach [ P1-101 ]
4. exceedance [ P1-54 ]
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本文链接地址：第31课 大气数据系统 LESSON 31 AIR DATA SYSTEM(13)
