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because the airplane stalls at higher-than-published speeds with ice accumulation. On final approach for landing, increased airspeed must be maintained to compensate for this increased stall speed. After touchdown with heavy ice accumulation, landing distances may be as much as twice the normal distance due to the increased landing speeds. In this chapter, ice prevention and ice elimination using pneumatic pressure, application of heat, and the application of fluid is discussed. 

The ice and rain protection systems used on aircraft keep ice from forming on the following airplane components: 

• Wing leading edges 

• Horizontal and vertical stabilizer leading edges 

• Engine cowl leading edges 

• Propellers 

• Propeller spinner 

• Air data probes 

• Flight deck windows 

• Water and waste system lines and drains 

• Antenna 

Figure 15-3  gives an overview of ice and rain protection systems installed in a large transport category aircraft. In 

modern aircraft, many of these systems are automatically controlled by the ice detection system and onboard computers. 

## Ice Detector System 

Ice can be detected visually, but most modern aircraft have one or more ice detector sensors that warn the flight crew of icing conditions. An annunciator light comes on to alert the flight crew. In some aircraft models, multiple ice detectors are used, and the ice detection system automatically turns on the WAI systems when icing is detected. [Figure 15-4] 

## Ice Prevention 

Several means to prevent or control ice formation are used in aircraft today: 

1. Heating surfaces with hot air 

2. Heating by electrical elements 

3. Breaking up ice formations, usually by inflatable boots 

4. Chemical application 

Equipment is designed for anti-icing or for deicing. Anti-icing equipment is turned on before entering icing conditions and is designed to prevent ice from forming. A surface may be anti-iced by keeping it dry, by heating to a temperature that evaporates water upon impingement, or by heating the surface just enough to prevent freezing, maintaining it running wet. 

<img src='content_image/588814.jpg'>

