Pitot source blocked Increases with altitude gain,  decreases altitude loss. Decreases with altitude gain,  increases with altitude loss. Both static sources blocked Both static and pitot sources blocked Does not change with actual  gain or loss of altitude. Does not change with actual  variations in vertical speed. Unaffected Inaccurate while sideslipping; very sensitive in turbulence. One static source blocked All indications remain constant, regardless of actual  changes in airspeed, altitude, and vertical speed. Unaffected XPDR 5537 IDNT LCL23:00:34 VOR 1 270 ° 2 1 1 2 3 300 3 200 3 100 4 000 2 900 2 800 2300 60 20 3 000 130 120 110 90 80 70 1 100 9 TAS 100KT NAV1 108.00 113.00 NAV2 108.00 110.60 134.000 118.000 COM1 123.800 118.000 COM2 $_{WPT }$_ _ _ _ _ _$_{ DIS}$ _ _ ._ $_{NM}$ $_{DTK }$_ _ _$_{°}$ TRK 360° MAP - NAVIGATION MAP ADF/DME MSG D195I D212I A212I HDG UP 10 NM 140 160 200 250 AIRSPEED KNOTS IAS TAS 40 60 80 100 120 140 160 180 200 260 Indicated Airspeed Indicated Altitude Indicated Vertical Speed Indicated Airspeed Indicated Altitude Indicated Vertical Speed Effect of Blocked Pitot/Static Sources  on Airspeed, Altimeter, and Vertical  Speed Indications Figure 17-10.  Effects of blocked pitot-static sources. of Federal Regulations (14 CFR) part 23 for IFR flight,  redundant instrumentation is required for electronic displays  of airspeed, altitude, and attitude indications. Dedicated  standby instruments or dual independent pilot flight displays  (PFD) must be installed in the aircraft. Many of the light  aircraft equipped with glass cockpits typically share the same  pitot-static inputs for the backup instrumentation. Since both  systems are receiving the same input signals, both may be  adversely affected by obstructed or blocked pitot tubes and  static ports making redundancy much less than desired. Some  manufacturers combine both the air data computer (ADC) and  the attitude and heading reference system (AHRS) functions  so that a blockage of the input system may also affect the  attitude display. It is imperative for pilots to obtain equipment-specific  information in reference to both the aircraft and the avionics  that fully prepare them to interpret and properly respond  to equipment malfunctions of electronic flight instrument  displays. Rapidly changing equipment, complex systems,  and the difficulty or inability to simulate failure modes and  functions can impose training limitations. Pilots still must  be able to respond to equipment malfunctions in a timely  manner without impairing other critical flight tasks should  the need arise.  The AFM/POH for the specific airplane contains information  that should be followed in the event of any abnormal engine  instrument indications. The table shown in  Figure 17-11 offers generic information on some of the more commonly  experienced in-flight abnormal engine instrument indications,  their possible causes, and corrective actions.  With conventional instrumentation, the design and  operation are similar regardless of aircraft or manufacturer.  By comparing information between the six conventional  instruments, pilots are able to diagnose common failure  modes. Instrument failure indications of conventional  instruments and electronic flight displays may be entirely  different, and electronic systems failure indications are not  standardized. With the wide diversity in system design of  glass cockpits, the primary display and the backup display  may respond differently to any interruption of data input,  and both displays may function differently than conventional  instruments under the same conditions. In most instances, the occurrence of an inadvertent door  opening is not of great concern to the safety of a flight, but  rather, the pilot’s reaction at the moment the incident happens.  A door opening in flight may be accompanied by a sudden loud  noise, sustained noise level, and possible vibration or buffeting.  If a pilot allows himself or herself to become distracted to the  17-13 Door Opening In-Flight Abnormal Engine Instrument Indication