Data-link:Fact and Fiction

Kim O’Neil

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 one’s 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 VDL2&3 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…. A A T

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Global Standard VDL2 VDL3 VDL4

Block to Block No No YesAvailability No Yes YesIntegrity Yes Yes YesRobustness No ? YesSpectrum Efficiency No No YesCapacity No No YesFuture Needs No ? YesTransition ? ? Yes

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)

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