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Helicopter precision approaches using GNSS


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Talk for the IET EC3 section,Wokingham, April 2013
Presenter: Philip Church of Helios
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Helicopter precision approaches using GNSS

  1. 1. www.askhelios.comSpaceTelecomsAir Traffic ManagementAirportsRailMaritimeHelicopter precisionapproachesusing GNSSPhilip Church25 April 2013Presentation for IET EC3 Section
  2. 2. 1Helios is the leading management and technologyconsultancy in air transportWe aim to be our customers’ first choiceCompany overviewPerformanceimprovementPerformanceimprovementRegulationRegulationBusiness economicsBusiness economicsSafety & securitySafety & securityEnvironmentEnvironmentTechnology & innovationTechnology & innovationPlanning & procurementPlanning & procurementTrainingTrainingPerformanceimprovementPerformanceimprovementRegulationRegulationBusiness economicsBusiness economicsSafety & securitySafety & securityEnvironmentEnvironmentTechnology & innovationTechnology & innovationPlanning & procurementPlanning & procurementTrainingTraining• leading consultancy specialising in airtransport, airports and in Air TrafficManagement• Also working in space, rail, maritime,telecoms and defence• Established in 1996• Joined Egis, an internationalengineering and infrastructure group,in January 2013• Headquarters in Farnborough UK• Turnover: ~£5M• Over 70% of revenue from exports,mainly within Europe• Two Queen’s Awards forEnterprise (2004, 2009)Customer baseServices areas
  3. 3. Overview2Difficulties of the offshoreenvironment‘Existing’ approach procedures‘Safety’ assessment of ‘existing’proceduresProposed mitigationsFuture steps
  4. 4. www.askhelios.comSpaceTelecomsAir Traffic ManagementAirportsRailMaritimeDifficulties of theoffshore environment3
  5. 5. 4Operations
  6. 6. Helicopter precision approaches using GNSS5
  7. 7. Helicopter precision approaches using GNSS6
  8. 8. Helicopter routes in the North SeaHelicopter precision approaches using GNSS7
  9. 9. Platform locations in the North Sea8
  10. 10. Flights during low cloud base• Navigation based on Airborne Weather Radar Approach(ARA)• Defined in:• TSO C63c - (Airborne Weather and Ground Mapping PulsedRadars)• TSO C102 - (Airborne Radar Approach and Beacon Systems forHelicopters)9Standard first established in 1959!!
  11. 11. The ARA10No vertical guidance / Low level turns
  12. 12. ARA guidance11+-- LUM +-- BRGON/OFF +-- CRTSDMAP MISD NAVD FND
  13. 13. www.askhelios.comSpaceTelecomsAir Traffic ManagementAirportsRailMaritimeExisting regulatory(equipment)requirements12
  14. 14. Equipment carried13
  15. 15. Industry standards• Standards checked in relation to weather radar:• TSO C63c - (Airborne Weather and Ground Mapping PulsedRadars)• TSO C102 - (Airborne Radar Approach and Beacon Systems forHelicopters)• AC 90-80B - (Approval of Offshore Standard ApproachProcedures, Airborne Radar Approaches, and Helicopter EnRoute Descent Areas)• RTCA DO-172 - (MOPS for Airborne Radar Approach and BeaconSystems for Helicopters)• RTCA DO-173 - (MOPS for Airborne Weather and GroundMapping Pulsed Radars)• Standards checked in relation to radio altimeter:• TSO C87 – (Airborne low range radio altimeter)14
  16. 16. What do the standards describe?• Maintenance requirements• Performance requirements• accuracy• range• azimuth• target size• Test procedures• during maintenance• during pre-flight checks15
  17. 17. Point of interestAC 90-80BTSO C63cTSO C102DO-172 TSO DO-173Indicated range error:• ± 0.2NM for displays of5NM or lessIndicated range error:• < 10% of actual targetdistance, or• 1NM, whichever greaterIndicated range error:• < ± 600ft (2) fordistances of 5NM or less forPhase I• < ± 300ft (2) for Phase II• < 5% of indicated rangefor ranges > 5NM16
  18. 18. RDR-1400 technical specifications• Certification:• Radar certified by FAA to:° TSO C63b° TSO C102• Installation and maintenance manuals supplied in accordancewith TSO.• Repairs are upon fault indication or pilot malfunction report.• Reliability:• False alarm rate is 5 indications per 120º scan i.e. 10-6.• Accuracy with respect to range and azimuth meet and exceedthe +/- 2% requirement of TSO DO-172 and 173.• Expected MTBF of 1600 hours in continuous use.• Analyzed to have a probability of generating misleading data of2.18 x 10-6.17
  19. 19. www.askhelios.comSpaceTelecomsAir Traffic ManagementAirportsRailMaritimeSafety concerns18
  20. 20. Mandatory Occurrence Reports (MORs)20Event type Number ofoccurrencesFirst report Latest reportIncorrect or unavailable wind dataprovided4 April 1976 November 2003Incorrect QFE/QNH to a/c 6 December 1977 February 2001Crashed in poor visibility 1 November 1981Loss of separation between helicopters 1 November 2004Descended below decision height 1 June 2003NDB procedural problem 1 March 1983Helicopter landed on wrong rig 11 July 1989 November 2004Misidentified rig 2 May 1990 August 1994NDB off on rig 1 March 1981NDB interference 4 April 1986 June 1994Loss of weather radar 1 February 1984Erroneous ADF display 1 April 1996Loss of displays 1 August 1999Malfunction of altimeter 5 August 1985 March 2001
  21. 21. Helicopter Operations Monitoring Programme(HOMP) events• The two incidents recorded are:• Helicopter climbing into cloud on approach° Flight crew inadvertently climbed 50ft into cloud base• Helicopter breaking vertical minima on approach° Flight crew incorrectly flew approach at below minimum descentheight21
  22. 22. Confidential Human Factors Incident ReportingProgramme (CHIRP) - Hazards• Pilot descending below MDH• Weather radar not calibrated• Approach too close to rig (horizontal minima nowchanged)• Approach below deck height (vertical minima nowrevised)• Miscommunication between crew• Weather radar not calibrated• Crew breaking minima / ad quality of Met data• Pilot descending below MDH22
  23. 23. Risk matrix assessment• EASA CS 25.1309 risk matrix• EASA probability classification23SeverityCATASTROPHIC HAZARDOUS MAJOR MINORFrequencyPROBABLE UNACCEPTABLE UNACCEPTABLE UNACCEPTABLE TOLERABLEREMOTE UNACCEPTABLE UNACCEPTABLE TOLERABLE NEGLIGIBLEEXTREMELY REMOTE UNACCEPTABLE TOLERABLE NEGLIGIBLE NEGLIGIBLEEXTREMELY IMPROBABLE TOLERABLE NEGLIGIBLE NEGLIGIBLE NEGLIGIBLEFrequency category Quantitative descriptionPROBABLE Failure condition frequency is more than 10-5 per aircraft flight hourREMOTE Failure condition frequency is between 10-7 and 10-5 per aircraft flight hourEXTREMELY REMOTE Failure condition frequency is between 10-9 and 10-7 per aircraft flight hourEXTREMELY IMPROBABLE Failure condition frequency is less than 10-9 per aircraft flight hour
  24. 24. Offshore Weather Radar Approaches – Safetyassessment24Conflict Scenario Severity Probability Result1a. The flight crew approach the wrong installation and come intoconflict with another helicopter.CATASTROPHIC EXTREMELYIMPROBABLETOLERABLE1b. The flight crew land on the wrong installation and it is in anunsafe condition.CATASTROPHIC EXTREMELYREMOTEUNACCEPTABLE2a. The helicopter comes into conflict with the sea due to crew error. CATASTROPHIC < EXTREMELYIMPROBABLENEGLIGIBLE2b. The helicopter comes into conflict with the sea due to altimeterfailureCATASTROPHIC EXTREMELYIMPROBABLETOLERABLE3a. The helicopter comes into conflict with an obstacle due to flightcrew error.CATASTROPHIC EXTREMELYIMPROBABLETOLERABLE3b. The helicopter comes into conflict with an obstacle due to theabsence of the obstacle on the weather radar display.CATASTROPHIC EXTREMELYIMPROBABLYTOLERABLE4a. The helicopter comes into conflict with the destination installationdue to flight crew error.CATASTROPHIC REMOTE UNACCEPTABLE4b. The helicopter comes into conflict with the destination installationdue to unannunciated weather radar malfunction.CATASTROPHIC EXTREMELYREMOTEUNACCEPTABLE
  25. 25. So something better is needed• Manually interpretedapproach• Reliance on the weatherradar for obstacleclearance• Helicopter operations canbe limited by lack ofnavigation equipment25• GPS/SBAS can help, but limited use so far• Increasingly dependent on GPS with gradual removalof NDB’s from platforms
  26. 26. CAA requires action• CAA Paper 2009/06 noted failings of current facilitiesand improvements from GPS stating:26“… the fact that most hazards remain "TOLERABLE" (not"NEGLIGIBLE") means that it is not a panacea and still hasshortcomings in areas such as vertical navigation. It isrecommended that work continues to address theseshortcomings …”
  27. 27. www.askhelios.comSpaceTelecomsAir Traffic ManagementAirportsRailMaritimeBenefits of RNAV27
  28. 28. The change in navigation28
  29. 29. Before RNAV29
  30. 30. After RNAV30
  31. 31. RNAV vs RNP• “RNAV” means the aircraft can follow a pre-definedtrack with 1 NM accuracy 95% of the time• “RNP” means the aircraft can follow a pre-definedtrack with 1 NM accuracy 95% of the time AND there ison-board monitoring and alerting that warns the pilot ifaccuracy is insufficient1 Nautical Mile 95% of flight time1 Nautical Mile 95% of flight timeTrack CenterlineFor example, RNAV 1:31
  32. 32. Navigation errors• Lateral navigation errors (95% of flight time)• Characterized by the Total System Error (TSE)Desired PathDefined PathEstimated positionActual positionPath Definition Error Flight Technical ErrorNavigationSensorErrorTotalSystemErrorTSE is the Root Sum Square (RSS) of 3 errors: PDE, NSE and FTEThe navigation accuracy the aircraft achieves in practice is knownas the Actual Navigational Performance (ANP)32
  33. 33. So what work has been completed for helicoptersto date?• Focus on GNSS implementations to date have beenmostly fixed wingMIELEC33
  34. 34. The SBAS Offshore Approach Procedure (SOAP)35Straight approach – no turning / Vertical guidance
  35. 35. SOAP offers several significant advantages• Less reliance on weather radar (combined with AIS)• Independent cross-check against existing altimeters• Allows a “straight in” procedure from final to missedapproach• Enables autopilot to lower crew workload• High navigation accuracy36Developed as a safety enhancement to currentprocedures
  36. 36. www.askhelios.comSpaceTelecomsAir Traffic ManagementAirportsRailMaritimeWhat about the integrityof the GNSS signal forhelicopters?37
  37. 37. Reception of GNSS signals affected more onrotorcraft• EGNOS GEOs broadcast SBAS correction message at alow elevation angle in the operating areas• Suggests the EGNOS signal may be more vulnerable tomasking and rotor interference than GPS• Due to its lower specified maximum and typical power levels• GPS presently radiates well above the specified level• Structural limitations mean less options of mountingGNSS antenna38CAA PAPER 2003/7 - Effect of Helicopter Rotors onGPS Reception
  38. 38. North Sea EGNOS reception tests39
  39. 39. The ‘test’ rig40
  40. 40. North Sea EGNOS reception testsHelicopter precision approaches using GNSS41
  41. 41. North Sea EGNOS reception tests42Helicopter pitch and roll angles during flight-20-10010203040483,500 484,000 484,500 485,000 485,500 486,000GPS seconds in weekPitch/RollAngle(deg)PitchRollPRN120PRN124PRN126Taxi-out Take off Orbits Approaches Final approach, landing & taxi to standPitch upon takeoffConsecutive loss of Geos during orbit
  42. 42. North Sea EGNOS reception tests43Helicopter heading during flight trial090180270360483,000 483,500 484,000 484,500 485,000 485,500 486,000GPS seconds in dayMagneticheading(deg)HdgPRN120PRN124PRN126
  43. 43. Validation of the signal under HEDGE• Under HEDGE further analysis of EGNOS reception:• 485 flights = 689 hours, 15 minutes and 44 seconds of flight• 127 hours of recorded data on different SBAS receivers• 4,591,662 points analysed44
  44. 44. Validation of the signal under HEDGE45Vertical Standford Plot Horizontal Standford Plot
  45. 45. SOAP equipment integration
  46. 46. Back-end palletAIS receiverGNSS receiverDevelopment and logging laptopARINC 429serialconverter47
  47. 47. Flight crew installationInstrument displayBlanking plate48
  48. 48. 49
  49. 49. On-board installationRear pallet installedFlight crew displayinstalled50
  50. 50. Flight crew display51
  51. 51. Flight trials
  52. 52. Flight schedule approachesFlight # Approach # Descent slope Wind LDG/GA Approach #11 4° Into GA Data lost2 6° Out of GA 14443 4° Out of LDG 14594 Pilot choice Pilot choice Pilot choice 151321 4° Into GA Data lost2 6° Out of GA 10243 4° Out of LDG 10394 Pilot choice Pilot choice Pilot choice 105831 4° Into GA 13222 6° Out of GA 13343 4° Out of LDG 13534 Pilot choice Pilot choice Pilot choice 140753
  53. 53. Lateral path deviations05010015020025017131925313743495561677379859197103109115121127133139145151157163169175181187193199205211217223229235241247253259265271277283289295301Errorinmetres1024 1039 1058 1322 1334 1353 1407 1444 1459 151354
  54. 54. Vertical path deviations01020304050607017131925313743495561677379859197103109115121127133139145151157163169175181187193199205211217223229235241247253259265271277283289295301Errorinmetres1024 1039 1058 1322 1334 1353 1407 1444 1459 151355
  55. 55. Flight path errors• Lateral deviations• Vertical deviations1444 1459 1513 1024 1039 1058 1322 1334 1353 1407 OverallMean 30.79 56.64 34.97 49.18 27.97 10.87 33.45 8.06 15.73 11.91 26.93Max 88.53 230.19 164.36 150.07 121.94 60.11 72.97 42.27 48.80 23.05 230.19Standarddeviation23.49 72.35 38.20 45.60 26.36 7.90 18.80 7.58 13.29 6.36 35.221444 1459 1513 1024 1039 1058 1322 1334 1353 1407 OverallMean 17.03 11.77 11.03 9.03 9.54 12.88 9.10 9.97 10.12 18.26 11.80Max 65.97 25.48 28.75 23.60 20.95 24.30 19.07 27.25 36.71 33.28 65.97Standarddeviation20.39 7.51 7.63 6.58 7.03 6.89 5.14 8.55 11.90 9.37 10.01Overall26.93230.1935.22Overall11.8065.9710.0156
  56. 56. www.askhelios.comSpaceTelecomsAir Traffic ManagementAirportsRailMaritimeFuture development57
  57. 57. HMI changes to aid manual descent58
  58. 58. HMI aid to level off anticipation in manual descent59
  59. 59. SOAP has successfully validated and continues tobe improved• Flight crew agreed that SOAP is more precise thanexisting low visibility options• Horizontal and vertical track keeping is precise butincreases crew workload• Coupling with autopilot required• Further work in the area will be undertaken• UK CAA sponsoring HMI enhancements and additional flighttrials60
  60. 60. www.askhelios.comSpaceTelecomsAir Traffic ManagementAirportsRailMaritimeThank you for your