Digital Avionics II

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Digital avionics II

Class Presentation CP 2


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To enable the flight crew to carry out the aircraft

mission safely and efficiently

Mission is carrying passengers to their destination(Civil Airliner)

Intercepting a hostile aircraft, attacking a groundtarget, reconnaissance or

maritime patrol (Military Aircraft)

Why Avionics Systems


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CORE AVIONICS FUNCTIONS


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Aircraft Mission Requirements to Avionics

System Requirements


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Starting point for designing a digital Avionics system is a clear

understanding of the mission requirements and the

requirement levied by the host aircraft

Top-level Requirement for Military

The customer prepares the statement of need and top-level

description of possible missions

Describes the gross characteristic of a hypothetical aircraft that could

fly the mission

Customer may also describe the mission environment and definestrategic and tactical philosophies and principles and rules of

engagement.

Avionics System Design


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Capability

Reliability

Maintainability

Certificability Survivability(military)

Availability

Susceptibility

vulnerability Life cycle cost(military) or cost of ownership(civil)

Weight & power

Major Req of Avionics System


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Capability:

How capable is avionics system?

can they do the job and even more?

Designer to maximize the capability of the systemwithin the constraints that are imposed.

Reliability: Designer strives to make systems as reliable as

possible.

High reliability less maintenance costs.

If less reliable customer will not buy it and interms of civil airlines the certificating agencies willnot certify it.


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Maintainability:

Closely related to reliability

System must need preventive or correctivemaintenance.

System can be maintained through built in testing,automated troubleshooting and easy access to

hardware. Availability:

Combination of reliability and maintainability

Trade of between reliability and maintainability to

optimize availability. Availability translates into sorties for military aircraft

and into revenue flights for civil aircrafts.


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Certificability:

Major area of concern for avionics in civil airlines.

Certification conducted by the regulatory agencies

based on detailed, expert examination of all facets

of aircraft design and operation.

The avionics architecture should be straightforward and easily understandable.

There should be no sneak circuits and no

noobvious modes of operation.

Avionics certification focus on three analyses:

preliminary hazard, fault tree, and FMEA.


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SONAR

RADAR

Military communications Electro optics (FLIR or PIDS)

ECM OR ECCM

ESM Tactical missile guidance

Integrated Avionics weapon systems


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Essential :A function is essential if its loss degrades the flight

control system beyond operational state III.

Flight Phase Essential:Same as essential except it applies only

during specific flight phases.

Non-Critical:Loss of function does not effect flight safety or

reduce control capability beyond that required for operation

state III

Criticality Classification Definitions-9490


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Five operational States for the flight control system:

Operational State I: Normal Operation

Operational State II: Restricted Operation

Operational State I: Minimum safe Operation

Operational State I: Controllable to an immediate

emergency landing

Operational State I: Controllable to an evacuable flightcondition

Requirements of MIL-F-9490


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Probability of failuresFAR 25.1309


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Primary flight information,

Navigation information, Engine data,

Airframe data,

Warning information.

Infrared imaging sensors,

Radar,

Tactical mission data,

Weapon aiming,

Threat warnings.

Military aircrafts

Primary information required

Crucial Information reqd

Heading

Altitude

Airspeed

Rate of turn

Rate of climb (or descent)

Attitude (relative to the horizon )


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Modern Integrated Primary Flight Info Display


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Instrument layout in AIRBUS 320


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Measurement Units : Generally Followed

Pressure : 1 millibar = 100 N/m^2 = 100 Pa

Distance : 1NM = 6076 .1155 ft = 1852 m

Speed : 1 Knots : 0.5144 m/sec ~ 0.5 m/sec

1 m/s = 2 knots


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Digital Avionics II

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