Data-link: Fact and Fiction

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Data-linkFact and Fiction

• Kim ONeil
• Advanced Aviation Technology Ltd.
• www.aatl.net

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Data-link Fact Fiction

• Decision Process
• Safety
• Key Factors
• Comparison of Data-links
• Conclusions.

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Decision Process

• Who Chooses?
• ICAO? CAAs? Airlines? Eurocontrol? ECAC?
• What Criteria?
• Safety? Cost? Benefits? Functionality?
• Commercial Interest? Spectrum Efficiency?
• Political expediency? Vested Interest?
• ...or something else?

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Decision Process

• Probable Answer All of the above.
• Implies - No Perfect Solution
• i.e. some ones going to be unhappy..
• Also implies - A LOT of Confusion!

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Decision Process

• WHAT Application?.
• CPDLC?
• AOC?
• ASAS? ADS-B? Etc. Etc.
• Different Datalinks for each?
• Aerials????
• Or one Datalink for all?

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Safety

• Is Safety an Issue?
• Application dependent
• Typical Factors
• Integrity
• Reliability
• Availability
• Communication delays
• Security

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Certification

• Certification
• Equipment, installation, maintenance
• People, procedures, safety management
• HMI, human factors..
• Operations..
• Applications.

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Certification

• End to End Certification?
• Implies certification of Network
• NEVER been done before.
• Legally impossible
• Outside authority of CAAs.
• Regulators will have to work hard..

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Certification

• Certification Necessary
• e.g. for time critical applications
• If no application safety standards
• then no operational certification..
• Conformance is NOT Safety
• Safety Cases are not enough.

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Decision Factors

• Many Players
• Airlines
• ATC
• Telecom providers
• Manufacturers
• Many priorities
• Consensus difficult
• Vested Interests.

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Decision Factors

• Commitment?
• Airlines watch service providers
• Service providers watch ATC
• ATC watch airlines
• Manufacturers watch everyone.
• Or lack of comittment?
• CAAs not installing VDL2
• BUT want others to.

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Decisions VDL mode 4

• Russia
• Entire Surveillance System
• Communication Services, more.
• European States
• Intensive evaluation and trials.
• NEAN/NUP, FARAWAY etc. etc. etc.
• CPDLC over VDL4 prototypes

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Functionality

• CPDLC
• A long road
• Required functionality depends on timescales.
• Quick Fix may be counter-productive
• Beware dead-end solutions
• NEED a highly adaptable data-link

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Spectrum Efficiency

• Key Issues
• NEED 25 kHz service
• Essential for frequency planning
• No interference to voice
• Frequency re-use
• Capacity
• No special protection

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Transition

• LONG Transition period
• NEED a Transition Strategy
• MUST coexist with existing system
• VDL23 increase pressure on spectrum
• ACARS to VDL2 requires more frequencies
• CPDLC and AOC share frequencies????

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Feasibility

• VDL mode 4 widely demonstrated
• 100,000 flight hours on commercial aircraft
• many demonstrations, evaluations, simulations
• including CPDLC!
• VDL mode 2?
• VDL mode 3?

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Cost/Benefits

• Airlines sensitive to costs
• Equipment, installation, certification
• Maintenance, crew training,
• Operating fees.
• Minimal cost to ATC
• Favourable contracts with service providers
• Communication providers business drivers
• Want to expand and want more spectrum..

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Cost/Benefits

• NEED to address entire operational life
• the future?
• Ideally fit ONLY one data-link
• with operational redundancy
• NEED to compare datalink options
• assess each against future needs
• calculate the cost
• guestimate the benefits

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Comparing Datalinks.
Global Standard VDL2 VDL3 VDL4 Block to
Block No No Yes Availability No Yes Yes Integ
rity Yes Yes Yes Robustness No ? Yes Spectru
m Efficiency No No Yes Capacity No No Yes Fut
ure Needs No ? Yes Transition ? ? Yes
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Conclusions

• ICAO sets Standards
• Does not mandate technologies
• States decide
• VDL 2 has severe limitations
• VDL 3 has limitations ..and when?
• Risk loss of both Voice and Data
• Transition?

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Conclusions

• VDL mode 4 meets known requirements
• VDL mode 4 widely demonstrated
• VDL mode 4 can provide CDTI and ASAS
• Situation Awareness essential for CPDLC
• VDL mode 4 meets time critical requirements
• VDL mode 4 has higher capacity
• VDL mode 4 has graceful degradation

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Conclusions

• VDL mode 4
• Spectrum Efficient
• High capacity
• Long range
• Redundant
• Robust
• Expansible
• VDL mode 4 provides Seamless Transition

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The End!

• Thank You!
• (updated paper at WWW.AATL.NET)