Instrument Scan

IFR SCAN

Attitude Instrument Flying Method

·        Control and Performance Method   (attitude/Power to get desire performance)

o   Control instruments

§  Setup AI,   power ASI  and Altitude ALT

o   Performance Instruments (provides feed back to confirm support control instruments)

§  ASI, TC , DG, VSI, ALT

o   Navigation Instruments

§  VOR – Position of aircraft relative to facilitate or fix

·        Primary / Support method

o   Pitch control instrument  - ALT (Primary), VSI (Supporting) AI, ASI

o   Bank control instruments –Heading Indicator (DG) (Primary),  AI (supporting), TC,

o   Power control Instrument – ASI (Primary), TAC (supporting), Manifold Pressure (supporting)

•   Instrument cross check
•   Instrument interpretations
•   Aircraft Control – adjust pitch /bank/power

Problems of SCAN

• Omission 
• Fixation on one instrument
• Emphasizing on one instrument instead of combination of instruments

Types of Scan

1. Inverted 'V'      
• Attitude Indicator  => Vertical Speed Indicator  => Attitude Indicator
• Attitude Indicator =>  Turn Coordinator => Attitude Indicator
• Attitude Indicator  => Vertical Speed Indicator  => Attitude Indicator
• Note: Each instrument has a different source  VSI - Static Air, TC, Electrical, AI - Gyro 
2. Rectangular Cross Check
• ASI => AI => ALT => VSI => HI => TC
3. Radial Scan
1.  AI  => ALT  =>  AI => VSI  => AI => HI => AI => TC => AI => ASI => AI

6 Pack Key 

1. AI    - Attitude Indicator
2. ALT - Altimeter
3. VSI  - Vertical Speed Indicator
4. HI    - Heading Indicator (Directional Gyro)
5. TC   - Turn Coordinator
6. ASI  - Airspeed Indicator 

          Maneuvers                                              Pitch                                            Bank

1. Straight and Level Flight                         Altimeter                                      Heading Indicator