Total System Error Performance During Precision Approaches R. - - PowerPoint PPT Presentation

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Total System Error Performance During Precision Approaches R. - - PowerPoint PPT Presentation

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Total System Error Performance During Precision Approaches R. Geister, T. Dautermann, M. Felux, German Aerospace Center (DLR) www.DLR.de Chart 2 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux Contents -

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SLIDE 1

Total System Error Performance During Precision Approaches

  • R. Geister, T. Dautermann, M. Felux,

German Aerospace Center (DLR)

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SLIDE 2

> ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux www.DLR.de • Chart 2

  • GBAS mode of operation
  • Motivation
  • Introduction of error sources
  • Flight trial setup and methods
  • Presentation of results
  • Conclusion

Contents

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SLIDE 3

1) GNSS (GPS) signal

2) Every Reference Station compares received GNSS- Ranges with known Positions (Differential corrections) 3) Info about Pseudo-Range calculations and integrity data for every satellite in view 4) Transmission of GBAS data to MMR equipped A/C via VDB antenna

Source: AENA, OPTIMAL

GBAS Mode of Operation

www.DLR.de • Chart 3 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

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SLIDE 4

Motivation

  • GLS was introduced as “ILS look-alike” straight-in CAT I landing aid
  • Although certified as such, ICAO did not allow GLS as landing aid for

parallel approaches

  • The goal of this study was to gather data for ILS and GLS approaches

and enable parallel approaches with GLS

  • Flight trials with a transport category aircraft were conducted
  • To show:
  • GLS Total System Error (TSE) is at least as small as ILS TSE
  • GLS TSE is within requirements for precision approaches

www.DLR.de • Chart 4 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

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SLIDE 5

Error Sources

Total System Error (TSE) consists of:

  • Navigation System Error (NSE); the error between actual position and

the estimated position of the navigation system

  • Flight Technical Error (FTE); the error between defined flight path and

estimated position

  • Path definition Error (PDE) is neglectable

www.DLR.de • Chart 5 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

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SLIDE 6

Flight Trial Setup

  • DLR’s Advanced Technology Research Aircraft (ATRA)
  • Airbus A320-232

www.DLR.de • Chart 6 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

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SLIDE 7

Flight Trial Setup

www.DLR.de • Chart 7 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

  • Experimental cockpit display on F/O side
  • Manual flight only for all approaches
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SLIDE 8

Flight Trial Setup

www.DLR.de • Chart 8 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

  • Experimental curved GLS approaches (part of different investigations)
  • Error data on final approach segment used for this study
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SLIDE 9

Flight Trial Setup

www.DLR.de • Chart 9 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

  • Different flights used for investigations
  • Still a small sample size

Flight No. # Dates of Flights Date

  • No. of ILS

Appr.

  • No. of GLS Appr.

1 10/06/2011 3 2 10/06/2011 1 1 3 01/23/2013 3 4 09/19/2013 2 4

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SLIDE 10

Methods

  • Manually conducted ILS or GLS approaches used for investigations
  • Data used from straight final segment only (approx. 7km from threshold)
  • Position data from a Septentrio GNSS receiver used for investigations
  • Reference trajectory calculated with commercial software, dual frequency

GPS carrier phase solution (assumed true position)

  • GBAS position data calculated with PEGASUS toolset provided by

EUROCONTROL

  • ILS data taken from basic avionics recordings
  • FTE = Deviations; TSE = Distance between desired flight path and

reference trajectory

www.DLR.de • Chart 10 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

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SLIDE 11

Results – Total System Error ILS

  • Mean ILS TSE at a given distance to runway threshold
  • Standard deviation depicted as vertical bar
  • Black vertical line indicates decision height

www.DLR.de • Chart 11 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

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SLIDE 12

Results – Total System Error GLS

  • Mean lateral GLS TSE at a given distance to runway threshold
  • Triangles indicate number of samples for a given distance bin
  • Decreasing number of samples as go-arounds were conducted

www.DLR.de • Chart 12 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

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SLIDE 13

Results – Total System Error GLS

www.DLR.de • Chart 13 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

  • Mean vertical GLS TSE at a given distance to runway threshold
  • Triangles indicate number of samples for a given distance bin
  • Decreasing number of samples as go-arounds were conducted
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SLIDE 14

GLS Lateral Error Decomposition

www.DLR.de • Chart 14 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

  • Major error component of GLS TSE is the FTE (green)
  • Navigation System Error (NSE) is very small
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SLIDE 15

GLS Vertical Error Decomposition

www.DLR.de • Chart 15 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

  • Major error component of GLS TSE is the FTE (green)
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SLIDE 16

GLS Lateral Navigation System Error

www.DLR.de • Chart 16 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

  • Small sample size especially after 1km from runway threshold due to go-

arounds

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SLIDE 17

GLS Vertical Navigation System Error

www.DLR.de • Chart 17 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

  • Small sample size especially after 1km from runway threshold due to go-

arounds

  • Standard deviation slightly larger than in the lateral case
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SLIDE 18

Comparison ILS & GLS lateral TSE

www.DLR.de • Chart 18 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

  • Direct comparison in the last, straight part of the approach shows that the

TSE is similar

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SLIDE 19

Comparison ILS & GLS vertical TSE

www.DLR.de • Chart 19 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

  • Direct comparison in the last, straight part of the approach shows that the

TSE is similar

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Conclusion

  • The Flight Technical Error is the major error component of the GLS Total

System Error

  • The observed GLS TSE is at least as small as the observed ILS TSE
  • GLS TSE is within the assumptions of the Collision Risk Model (CRM) for

ILS category I approaches

  • CRM specifies a standard deviation of 22.4m for the lateral TSE at

1200m away from runway (observed lateral std. dev. < 4m)

  • As well as a standard deviation of 7m for the vertical TSE at 1200m

away from the runway threshold and a glide path angle of 3.5 degrees for Braunschweig airport (observed vertical std. dev. < 6m)

  • Even though the investigated sample size is small, the TSE of both

systems look similar and therefore, the use of GLS for parallel approaches should be allowed

www.DLR.de • Chart 20 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

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SLIDE 21

www.DLR.de • Chart 21 > ICRAT 2014 > Total System Error > R. Geister, T. Dautermann, M. Felux

Thank you very much for your attention!

Contact details: Thomas Dautermann Ph.D. Institute of Flight Guidance thomas.dautermann@dlr.de