Airbus training support & services Erroneous ILS Indications

© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. Content 01/07/2003Erroneous ILS Indications - V1.12 Content Most Valuable Lessons Most Valuable Lessons ILS: 2 Types Of Errors ILS: 2 Types Of Errors Erroneous ILS Signals Erroneous ILS Signals Erroneous Glide Slope Signal Erroneous Glide Slope Signal For All Types Of Approaches For All Types Of Approaches Efficient Crosscheck Efficient Crosscheck Use Of FMS Use Of FMS Use Of EIS Use Of EIS Conclusion Conclusion

© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. Content 01/07/2003Erroneous ILS Indications - V1.13 NOTAM terminology must be properly understood NOTAM terminology must be properly understood Operational consequences of potential system errors must be known Operational consequences of potential system errors must be known Proper crew procedures must be established to trap such errors Proper crew procedures must be established to trap such errors Never blindly trust even the most performant navaids Never blindly trust even the most performant navaids The NZ60 erroneous Glide Slope incident raises most valuable lessons to all aircrew: Most Valuable Lessons

© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. Content 01/07/2003Erroneous ILS Indications - V1.14 The NZ60 incident reminds us that an ILS can exhibit 2 types of errors False localizer and/or glide slope signals: False localizer and/or glide slope signals: Normal by-products of a valid ILS Normal by-products of a valid ILS Known phenomena by most pilots Known phenomena by most pilots Rapidly detectable by immediate cues Rapidly detectable by immediate cues (e.g. abnormal sink rates…) Erroneous localizer and/or glide slope signals: Erroneous localizer and/or glide slope signals: Very seldom occurrence (several “faults” involved) Very seldom occurrence (several “faults” involved) No (or very few) immediate cues available No (or very few) immediate cues available ILS: 2 Types Of Errors

© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. Content 01/07/2003Erroneous ILS Indications - V1.15 No flag displayed No flag displayed Normal ILS ident (transmitted by LOC transmitter) Normal ILS ident (transmitted by LOC transmitter) “On G/S” steady indication, regardless of actual A/C path “On G/S” steady indication, regardless of actual A/C path A/C sink rate may look quite reasonable A/C sink rate may look quite reasonable “Normal” Auto-Pilot / Flight Director / FMA behavior “Normal” Auto-Pilot / Flight Director / FMA behavior Most probably NO GPWS alert Most probably NO GPWS alert (except if out of sink rate tolerance) Design And Certification Requirements Erroneous ILS Signals In the particular case of an erroneous ILS signal:

© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. Content 01/07/2003Erroneous ILS Indications - V1.16 In case of an erroneous glide slope signal, only proper crew procedure can trap such an error: Periodic distance / altitude crosschecks are required Periodic distance / altitude crosschecks are required (one single crosscheck is not enough) Use of simple rule of thumb prevents gross errors Use of simple rule of thumb prevents gross errors(300ft/nm) Design And Certification Requirements Erroneous Glide Slope Signal

© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. Content 01/07/2003Erroneous ILS Indications - V1.17 The NZ60 incident raises lessons for all types of approaches: Thorough flight preparation: NOTAM unclear terminology, if any, to be clarified with dispatcher Thorough flight preparation: NOTAM unclear terminology, if any, to be clarified with dispatcher Thorough approach briefing: in case primary approach mean suspected doubtful, prepare a secondary approach strategy Thorough approach briefing: in case primary approach mean suspected doubtful, prepare a secondary approach strategy Exercise strict vigilance during approach: be trustful only after efficient crosschecks Exercise strict vigilance during approach: be trustful only after efficient crosschecks In case of serious doubt: immediately revert to secondary approach strategy or go-around without arguing In case of serious doubt: immediately revert to secondary approach strategy or go-around without arguing Design And Certification Requirements For All Types Of Approaches

© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. Content 01/07/2003Erroneous ILS Indications - V1.18 An efficient crosscheck means to use independent data such as: Altitude: baro. altitude, radio altitude Altitude: baro. altitude, radio altitude Distance: DME, marker, FMS, … Distance: DME, marker, FMS, … Bearing: LOC, VOR, ADF, FMS, … Bearing: LOC, VOR, ADF, FMS, … Flight path: G/S, DIST / ALT, FPA, sink rate, … Flight path: G/S, DIST / ALT, FPA, sink rate, … FMS data: FMS data: BRG / DIST to runway threshold on PROG page BRG / DIST to runway threshold on PROG page XTK if FMS F-PLN properly sequenced XTK if FMS F-PLN properly sequenced TAWS (e.g. GPWS) TAWS (e.g. GPWS) Radar map Radar map Design And Certification Requirements Efficient Crosscheck

© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. Content 01/07/2003Erroneous ILS Indications - V1.19 For efficient crosschecks, FMS data are intuitive and valuable, provided navigation accuracy is correct: Use Of FMS EIS ND : XTK and Distance MCDU PROG page: DIST and ACCUR

© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. Content 01/07/2003Erroneous ILS Indications - V1.110 For efficient crosschecks, data are available on EIS displays: Use Of EIS EIS ND: XTK and Distance EIS PFD: DME Distance, Altitude, Sink Rate

© AIRBUS S.A.S. All rights reserved. Confidential and proprietary document. Content 01/07/2003Erroneous ILS Indications - V1.111 Too much routine  Complacency  !… Too much routine  Complacency  !… Proper vigilance  enhances situational awareness Proper vigilance  enhances situational awareness   Improves flight safety As a conclusion: Conclusion