usually plumbed to a non-pressurized baggage compartment.  The pilot must activate the alternate static source by opening  a valve or a fitting in the flightdeck. Upon activation, the  airspeed indicator, altimeter, and the vertical speed indicator  (VSI) is affected and reads somewhat in error. A correction  table is frequently provided in the AFM/POH. Anti-icing/deicing equipment only eliminates ice from the  protected surfaces. Significant ice accumulations may form  on unprotected areas, even with proper use of anti-ice and  deice systems. Flight at high angles of attack (AOA) or even  normal climb speeds permit significant ice accumulations on  lower wing surfaces, which are unprotected. Many AFM/ POHs mandate minimum speeds to be maintained in icing  conditions. Degradation of all flight characteristics and large  performance losses can be expected with ice accumulations.  Pilots should not rely upon the stall warning devices for  adequate stall warning with ice accumulations. Ice accumulates unevenly on the airplane. It adds weight  and drag (primarily drag) and decreases thrust and lift. Even  wing shape affects ice accumulation; thin airfoil sections  are more prone to ice accumulation than thick, highly- cambered sections. For this reason, certain surfaces, such  as the horizontal stabilizer, are more prone to icing than the  wing. With ice accumulations, landing approaches should  be made with a minimum wing flap setting (flap extension  increases the AOA of the horizontal stabilizer) and with an  added margin of airspeed. Sudden and large configuration  and airspeed changes should be avoided. Deicing equipment is generally limited to pneumatic boots on  wing and tail leading edges. Deicing equipment is installed  to remove ice that has already formed on protected surfaces.  Upon pilot actuation, the boots inflate with air from the  pneumatic pumps to break off accumulated ice. After a few  seconds of inflation, they are deflated back to their normal  position with the assistance of a vacuum. The pilot monitors  the buildup of ice and cycles the boots as directed in the AFM/ POH. An ice light on the left engine nacelle allows the pilot  to monitor wing ice accumulation at night. Unless otherwise recommended in the AFM/POH, the  autopilot should not be used in icing conditions. Continuous  use of the autopilot masks trim and handling changes that  occur with ice accumulation. Without this control feedback,  the pilot may not be aware of ice accumulation building to  hazardous levels. The autopilot suddenly disconnects when  it reaches design limits, and the pilot may find the airplane  has assumed unsatisfactory handling characteristics. Other airframe equipment necessary for flight in icing  conditions includes an alternate induction air source and an  alternate static system source. Ice tolerant antennas are also  installed.  In the event of impact ice accumulating over normal engine  air induction sources, carburetor heat (carbureted engines)  or alternate air (fuel injected engines) should be selected. Ice  buildup on normal induction sources can be detected by a  loss of engine rpm with fixed-pitch propellers and a loss of  manifold pressure with constant-speed propellers. On some  fuel injected engines, an alternate air source is automatically  activated with blockage of the normal air source. The installation of anti-ice/deice equipment on airplanes  without AFM/POH approval for flight into icing conditions  is to facilitate escape when such conditions are inadvertently  encountered. Even with AFM/POH approval, the prudent  pilot avoids icing conditions to the maximum extent  practicable and avoids extended flight in any icing conditions.  No multiengine airplane is approved for flight into severe  icing conditions and none are intended for indefinite flight  in continuous icing conditions. An alternate static system provides an alternate source of  static air for the pitot-static system in the unlikely event  that the primary static source becomes blocked. In non- pressurized airplanes, most alternate static sources are  plumbed to the cabin. On pressurized airplanes, they are  Anti-icing/deicing equipment is frequently installed on  multiengine airplanes and consists of a combination of  different systems. These may be classified as either anti- icing or deicing, depending upon function. The presence  of anti-icing and deicing equipment, even though it may  appear elaborate and complete, does not necessarily mean  that the airplane is approved for flight in icing conditions.  The AFM/POH, placards, and even the manufacturer should  be consulted for specific determination of approvals and  limitations. Anti-icing equipment is provided to prevent  ice from forming on certain protected surfaces. Anti-icing  equipment includes heated pitot tubes, heated or non- icing static ports and fuel vents, propeller blades with  electrothermal boots or alcohol slingers, windshields with  alcohol spray or electrical resistance heating, windshield  defoggers, and heated stall warning lift detectors. On many  turboprop engines, the “lip” surrounding the air intake is  heated either electrically or with bleed air. In the absence of  AFM/POH guidance to the contrary, anti-icing equipment  should be actuated prior to flight into known or suspected  icing conditions. Anti-Icing/Deicing 12-8