Session 5 at SOAR by AVEMBSYS

               Session five began with an introduction to Avionics.The term Avionics is derived from Aviation Electronics.It consists of all electronic and electromechanical systems and subsystems(hardware and software) installed in an aircraft or attached to it.Avionics must be integrated in the conceptual design phase in the design of an aircraft.Aircrafts can be further classified as:

• Aircraft with ejection.eg:Civil Aircraft(probability of catastrophic failure<10-9/flight hour).
• Aircraft with ejection.eg:Fighter Aircraft(probability of catastrophic failure<10-7/flight hour).

                 The following are the basic principles:

1. Safety of an aircraft.
2. Mission of an aircraft.
3. Life Cycle Cost/Cost of Ownership.
4. Certification.

[note:
 FAA(Federal Aviation Administration) does the certification of aircrafts for the US.
 DGCA(Director General of Civil Aviation) does the certification for India.
 CEMILAC(Center for Military Airworthiness Certification) for military aircraft certification.]
                   The military IFF(Identify Friend or Foe) sends a code.Commercial aircrafts flying over a particular country's airspace send codes,which the radars fixed on the ground,catch.If the aircraft is not a civil aircraft(i.e if the IFF code does not match) the aircraft is shot considering it to be an enemy aircraft.These IFF codes are standard codes and cannot be manipulated easily.
                    The Avionics System consists of the following:Weather Radar,Glide Slope,Marker Beacon,DME(Distance Measuring Equipment),ATC Transponder(transmitter and receiver),TCAS,Radio Altimeter,VHF or UHF,FM Broadcast(communication between two pilots),ADF(Automatic Direction Finder),UHF Satcom(Satellite communication).
                    The next topic to be discussed was about navigation.Under navigation you have Absolute Navigation System,Dead Reckoning Navigation System and Mapping Navigation System(most widely
used).The various type of controls are:

• Flight Control
• Engine Control(electronic control of engine thrust).eg:FADEC which stands for Full Control Digital Engine Control System.
• Flight Management eg:FMS which stores th co-ordinates of the en route way points and calculates the steering signals to fly towards them(4D Navigation).
• Subsystem Monitoring and Control(faults in all subsystems are displayed).
• Collision Avoidance(predicts impending collisions with other aircrafts).eg:TCAS and EGPWS.                     

                   There are four types of data that is handled:

1. Fresh and valid data.(this is the data that is used)
2. Fresh but invalid data.(not to be considered)
3. Stale but valid data.(new data is read every 50ms).
4. Stale and invalid data.(useless data).

The next term discussed was the ELT(Emergency Location Transmitter).This is triggered automatically on high-g(high gravity).ELT's emit distinctive tones on 121.5,234,406 MHz.The 121.5MHz is the emergengy frequency.When tuned to this frequency,the ATC instructions can be heard.
                  For military aircrafts the Avionics Systems are different.Namely:

• Radar,Infrared and other Target Sensors.
• Weapon Management(Fire control and Stores management).
• Electronic Counter Measures.(ACAX)
• Mission Planning.(preflight mission planning)
• Formation Flight.

The Regulatory and Advisory Agencies are:

• ICAO-International Civil Aviation Organization,Canada.
• FAA-Federal Aviation Administration,USA
• FCC-Federal Communication Commission
• RTC-Requirements and Technical in aviation
• ARINC-Aeronautical Radio Incorporated
• SAE-Society for Automotive Engineers
• IEEE-Institution on Electrical and Electronic Engineers
• JAA-European Joint Aviation Authorities
• EUROCAE-European Organization for Civil Aviation Equipment
• DGCA UK,DGCA-Director General of Civil Aviation

The term EGPWS stands for Enhanced Ground Proximity Warning System.This system provides caution and warning to the pilot about terrain around the aircraft so that pilot can take necessary action.There are seven modes:

1. Excessive Descent Rate
2. Excessive Closure to terrain
3. Altitude loss after takeoff
4. Unsafe terrain clearence
5. Excessive glideslope deviation
6. Advisory Callout/Backangle
7. Wind Shear Alerting

The next system discussed was the TCAS(Traffic Collision Avoidance System).It has two types of alerts:

• Traffic Advisories(TAs)-assist pilot in the visual search for intruder aircrafts.
• Resolution Advisories(RAs)-resolve potential mid-air collisions.