AIRCRAFT AIRWORTHINESS STANDARDS FOR CIVIL UNMANNED … · Slide 1 Safety Regulation Group CAA-SRG visit to AIRCRAFT AIRWORTHINESS STANDARDS FOR CIVIL UNMANNED AIR VEHICLE SYSTEMS

Safety Regulation GroupSlide 1

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AIRCRAFT AIRWORTHINESSSTANDARDS FOR CIVIL

UNMANNED AIR VEHICLE SYSTEMS

Cliff Whittaker, Policy Manager,Design & Production Standards Division,

Civil Aviation Authority, UK

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Airworthiness of Civil UAVs

A complete “Poster Paper” covering thecontent of this presentation has beenprovided for inclusion on the conferenceCD.


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CAA Overall Objective

UAVs will pose no greater risk topersons or property in the air or on theground than that presented byequivalent manned aircraft.


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Existing civil aircraft:Regulatory environment includes definedstandards for:

• Airworthiness, (including Design, Production andContinued Airworthiness Management).

• Qualification of Personnel, (aircrew and groundcrew)

• Operation of Aircraft

• Air Traffic Management

• Etc…………


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This presentation covers the currentCAA policy for the AirworthinessCertification and regulation of theDesign and Production of civil UAVs

(It does not address the standards applicable to the approval ofoperations etc.).


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The future development potential of civil UAVsis unclear in many respects:

• Fleet size

• No limits (high or low) on aircraft size,mass, speed, range, endurance etc.

Any system of regulation we choose mustbe flexible enough to cope with anynumber of aircraft of any physical size andcapability.


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Alternative processes considered:

• Use of “Safety Target” approach;

• Certification by compliance withdefined minimum airworthinessstandards


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Safety Target Approach• Sets an overall “safety target”, (numerical)

• Focuses on critical features of the system

• Does not rely on commonly adopted designrequirements

• Combines operational and design requirements toachieve target – Example: Uncertainty over controlsystem integrity can be addressed by restrictingoperation to empty airspace over uninhabitedregions


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Certification by compliance with minimumairworthiness standards.

• Certification by compliance with comprehensivecodes of design requirements, (e.g. JAR 23), withadded Special Conditions as necessary

• Type Certification of the defined design.

• ICAO Certificates of Airworthiness for aircraft inconformity with the approved design.

• Wherever possible the design requirements do notpresume any particular role or mission.


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Safety Target or Code of Requirements?

• Expectation is that there will be an overallsafety target for the Operation of UAVs.BUT…….

• Will the Airworthiness contribution toreaching this target be a fixed, minimumstandard, (Code of Requirements); or avariable standard depending upon the role ofthe particular UAV and the restrictionsapplied to its operation?


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Review of Safety Target Approach.Use of Safety Target by the military is assistedby the following:

• The Government is both the regulator and the sole“Operator” – Easy to control frequency, duration,and location of operations to be consistent withrequired safety levels.

• No commercial competition in flying operations.

• Normally military aircraft are designed under contractto the customer – the operator’s missionrequirements are well-defined at the preliminarydesign stage


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Use of Safety Target approach for civil aircraftwould raise the following issues:

• Exports or international operations will requirerecognition of equivalent standards – Requiresagreement by all relevant countries on commonSafety Targets and on acceptable methods for thecompilation of safety cases.

• Any restriction of frequency, duration, or location ofoperations upon which the safety case relies mayhave a direct adverse effect on the profitability ofthe Operator. (Profit vs Safety).


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Use of Safety Target for civil aircraft - Issues -Continued:

• Civil aircraft are designed to appeal to as manypotential customers as possible. Designing toparticular missions may damage sales prospects.

• Any need to operate over populated areas mayrequire a very demanding Safety Target; it may notbe possible to provide sufficient data to justify that itwill be achieved.


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Existing legal framework for civil aircraft airworthiness

International conventions and treaties and theNational Legislation of all ICAO Member Stateshave the in-built assumption that civil aircraft willhave –

Certificates of Airworthiness granted on the basisof compliance with appropriate standards ofdesign and manufacture consistent with ICAOAnnex 8


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Safety Case - SummaryAdvantages:

• No need for comprehensive code of requirements

• Focus on safety critical areas

• Allows less demanding design standards if all operations willbe away from 3rd parties

Disadvantages:

• Design assumptions valid for anticipated missions only. Changeof mission may need a completely new safety case/re-design

• Reliance on operational restrictions to address shortfalls inairworthiness conflicts with commercial viability

• Not consistent with ICAO and national legislation


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Code of Requirements for Certification - SummaryAdvantages:

• Clarity over commonality of standards – Facilitates mutualrecognition of standards for export sales and internationaloperation.

• Role/mission changes can take credit for certification ofbasic vehicle, reducing re-certification costs and timescales

• No special, type-specific, operating restrictions to addressairworthiness uncertainties – Greater operational freedom– Avoids conflict between safety and commercial gain.


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Code of Requirements for Certification - SummaryAdvantages - continued:

• Familiar to existing civil aircraft industry. Clearminimum standards are defined at the designstage.

• Builds on past experience, giving confidence thatthe primary objective of “no greater risk” will beachieved.

• Fits existing international legal framework.Equivalence to existing manned civil aircraftstandards is a clear and defendable position


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Code of Requirements for Certification - Summary

Disadvantages:

• Requires compilation of a “Basis ofCertification”/Code of Requirements.

• May be unnecessarily demanding if the aircraft isalways to be operated well away from 3rd parties.


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Related issues:• UK industry wants UAV to mean:

“UNINHIBITED AIR VEHICLE”

Minimum of operating restrictions - equality withmanned aircraft – (Implies Code of Requirements & CofA)

• If the Safety Target is demanding, designers arelikely to choose compliance with existingairworthiness requirements as the most expedientmeans of justifying that the target will be achieved.


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Having considered all of these issues the CAA hasconcluded that civil certification of UAV Systems shouldfollow existing practice for manned civil aircraft. i.e.:

• The design of any civil UAV System shouldbe required to comply with a defined code ofairworthiness requirements to achieve “TypeCertification”

• Individual UAV Systems will be issued withCertificates of Airworthiness when they showconformity with the approved design


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Application of JARs/FARs to UAV guidance systems

• In common with manned aircraft thecomplete flight guidance system will have tobe included in the design certificationprocess.

• All systems and equipment which contributeto or can prejudice airworthiness, whether onboard the UAV or not, will be subject toregulation as part of the aircraft.


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Airworthiness Requirements for Civil Certification

If UAV Systems are to be certificated bydemonstration of compliance with codes ofairworthiness requirements, how are wegoing to compile those codes?


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Preamble to ICAO Annex 8 says:

“…the objective of international airworthinessstandards is to define..the minimum level ofairworthiness…for the recognition of certificates ofairworthiness…..thereby achieving, among otherthings, protection of other aircraft, third parties andproperty.”

i.e. The primary purpose of Annex 8 requirements isthe protection of third parties, not the occupants.


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So existing manned aircraft codes of requirements,(JARs/FARs), can be considered to be:

• a set of ICAO-related standards for the protectionof third parties;

supplemented by:

• cabin safety requirements aimed specifically at theprotection of occupants

It follows that a suitable starting point for a UAV code,could be JARs/FARs with the cabin safety requirementsdeleted, and Special Conditions added to addressremote guidance etc.


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A proposal to derive UAV airworthiness requirementsfrom manned aircraft codes raises two immediatequestions:

• Can the existing JARs/FARs be readily extended toaddress the autonomous/remote guidance ofUAVs?

• There are many JAR/FAR aircraft codes. Theseinclude the number of occupants in theirapplicability criteria. How should we selectrequirements from the existing JAR/FAR codes toconstruct the certification basis for a particulardesign of UAV System?


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1. Can the existing JARs/FARs be readily extended toaddress the autonomous/remote guidance of UAVs?

• Civil National Airworthiness Authorities have been verysuccessful in developing the requirements to cope with novelaircraft/technology.

• Modern Civil Large Transport Aeroplanes are highlyautomated; including automatic fault analysis and correctiveaction.

• When we have auto-take-off to complement auto-land etc., itmay become routine for airliners to complete their missionswithout a pilot operating the primary flying controls at anystage. i.e. Fully pre-programmed missions.

So we expect to be able to write suitable JARs for UAV controlsystems; (However, showing compliance with those JARsmay be difficult!)


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2. How should we select requirements from the existingJAR/FAR codes?

• Specialist knowledge.

• Experience and judgement.

• Consultation and discussion

Compiling a Certification Basis is always aniterative process involving:

But the process needs an initial preliminaryproposal as a starting point…………


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CAA method for obtaining a first estimate of theappropriate airworthiness standards

The capability of a vehicle to harm third partiesis broadly proportional to its kinetic energy onimpact


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CAA method for obtaining a first estimate of the appropriateairworthiness standards - continued

Consider two scenarios:

• Impact with the surface at a velocity appropriate toan emergency landing under control;(Unpremeditated Descent Scenario)

• Impact at a velocity resulting from loss of control ataltitude; (Loss of Control Scenario)

Calculate the kinetic energy for each impact forthe UAV and compare with similar calculationsmade for a wide range of certificated mannedaircraft -


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Comparison in terms of kinetic energy at impact(Schematic example only; for actual figures see Paper)


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CAA method for obtaining a first estimate of theappropriate airworthiness standards - continued

• Compare the UAV with the manned fleet for eachscenario – then choose the appropriate types ofrequirement to address (1) forced landing, and (2)loss of control, to the appropriate level.

• Add outline Special Condition paragraphs toaddress novel features, (e.g. remote guidance)

• Start refining this first estimate into an appropriateset of requirements


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CAA method for obtaining a first estimate of theappropriate airworthiness standards - continued

• This method is not a solution – just a starting point!

• It does not oblige the CAA to agree to any particularstandard.

• Precise calculation is not appropriate – The scale ofthe kinetic energy graph is logarithmic – We arelooking at orders of magnitude.

• It is a useful tool to start the process of compilingthe certification basis.


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Regulation of Design, Production and Maintenance

For a Certificate of Airworthiness to be valid thedesign requirements must be complied with, and

• The Design Organisation must be approved by theappropriate National Airworthiness Authority.

• The Production Organisation must be approved bythe appropriate National Airworthiness Authority.

• There will need to be appropriate arrangements toensure the UAV System is correctly maintained andremains in conformity with the approved design.


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Airworthiness of Civil UAVs - Summary

Complete UAV Systems will be required to qualifyfor Certificates of Airworthiness, by

• Demonstration of compliance with airworthinessstandards derived from existing manned aircraftrequirements.

• The civil certification will include any systemcomponents remote from the aircraft which supportor can affect airworthiness

• Organisations which design or manufacture civilUAV Systems will have to be approved under JAR21 or similar requirements


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Airworthiness of Civil UAVs - Summary

The primary reasons for adopting this position are:

• Using airworthiness standards derived from existingmanned aircraft requirements facilitates commonstandards – (International flight; Export sales).

• Type Certification reduces the re-certification required onmodification for role/mission changes.

• The use of airworthiness standards derived from existingmanned aircraft requirements of gives confidence that the“no greater risk” objective will be satisfied.

• The application of comprehensive codes of requirementsavoids additional operational limitations and hence apotential direct conflict between safety and commercialconsiderations.


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Questions?

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AIRCRAFT AIRWORTHINESS STANDARDS FOR CIVIL UNMANNED … · Slide 1 Safety Regulation Group CAA-SRG visit to AIRCRAFT AIRWORTHINESS STANDARDS FOR CIVIL UNMANNED AIR VEHICLE SYSTEMS