# Presentation: 387671

- 
- Flight Inspection Division

## Flight inspection of ground aviation facilities  experience with GPS

- Karel Kučera, Flight Checking Engineer
- Marek Dobrozemský, Flight Checking Engineer

## ILS, VOR, DME, NDB, VDF, COM
RADAR SYSTEMS
PAPI, VASIS
ALS, RLS
Flight Procedures
FM interference

- RADAR SYSTEMS
- PAPI, VASIS
- ALS, RLS
- Flight Procedures
- FM interference

- FID - Supervision of

## FID - Fleet

- Beechjet 400
- Business Category jet with an advanced dual Flight management and autopilot systems
- 150 to 320 KTS  IAS, GND to FL 450, 3hrs duration

- Let 410 UVP
- Commuter aircraft equipped with latest avionics, autopilot and GPS
- 80 to 200 KTS IAS, unpressurised, 3hrs duration, unpaved runways operation (600m)

## Method

- Comparing position indicated to reference one.

## RS Evolution

- Ground reference points
- Optical instruments
- Standard Theodolite
- Radio Telemetry Theodolite (RTT)
- Digital Radio Telemetry Theodolite (DRTT)

- GPS (DGPS, RTK)

## Steps utilising GPS

- 1992 new equipment NM 3625B on BE40
- 1993 - 1995 Testing period
- since 1994(1995) Operational use
- 1995 backup aeroplane L4T equipped NM 3625 B
- 1998 NM 3625 B - CR2 modified to RTK method
- 1999 NM 3625 B - CR3 modified to RTK method
- 2002 Omnistar corrections included

## ILS cat. III - critical application

- ILS points configuration

**Approach direction**

**Runway**

## ILS parameters

- Critical requirements

- Positioning system accuracy

- *at point B

## Gradual, following technology implemented
APRS (DGPS solution)
Static tests
Dynamic tests
RTK
Static tests
Dynamic comparisions
Theorethical evaluation

- APRS (DGPS solution)
- Static tests
- Dynamic tests
- RTK
- Static tests
- Dynamic comparisions
- Theorethical evaluation

- Testing

## DGPS, INS, LRF
declared accuracy: 1m horizontal, 1.5m vertical
required: 
PDOP < 2.4, 
HDOP < 1.5, 
>6 SATs in view,
 <100 km from reference station
LRF & post processing made possible vertical accuracy 0.14m 

- declared accuracy: 1m horizontal, 1.5m vertical
- required:
- PDOP < 2.4,
- HDOP < 1.5,
- >6 SATs in view,
-  <100 km from reference station
- LRF & post processing made possible vertical accuracy 0.14m

- APRS (history)

## First: comparing flight test results of both DRTT and APRS (same datalink used)
Second frequency added to data link -> REFERENCE CHECK procedure
91 approaches in horizontal plane
80 approaches in vertical plane
Declared accuracy confirmed
Scenarios: static and dynamic both in horizontal and vertical plane

- Second frequency added to data link -> REFERENCE CHECK procedure
- 91 approaches in horizontal plane
- 80 approaches in vertical plane
- Declared accuracy confirmed
- Scenarios: static and dynamic both in horizontal and vertical plane

- APRS Testing

## Static test in horizontal plane

- APRS Testing scenarios (1)

**WPT 1**

## Static test in vertical plane

- APRS Testing scenarios (2)

## Dynamic tests
approaches to two points (vertical, horizontal)
Reference check (APRS, DRTT)
DRTT placed to standard points for LLZ respective GP flight testing.
Horizontal: until E point
Vertical: until B point

- approaches to two points (vertical, horizontal)
- Reference check (APRS, DRTT)
- DRTT placed to standard points for LLZ respective GP flight testing.
- Horizontal: until E point
- Vertical: until B point

- APRS Testing scenarios (3)

## Sensor positions

- antenna vectors

## Static tests

- Test Results

- Dynamic tests

## Static tests performed - very optimistic results
Flight tests (RTK-DRTT comparison) confirms high degree of  accuracy
High accuracy ensured only if RTK „fixed“.
Problem to find „the ruler“ to verify dynamic measurements
Theoretical error assessment put in place

- Flight tests (RTK-DRTT comparison) confirms high degree of  accuracy
- High accuracy ensured only if RTK „fixed“.
- Problem to find „the ruler“ to verify dynamic measurements
- Theoretical error assessment put in place

- RTK

- RTK – accuracy considerations

## Technology Today

- Calibration Position Reference: GPS, DGPS, RTK
- up to dm accuracy in position
- up to ILS cat III flight checking
- DRTT as a backup
- long experience

## Standard deviation typically < 5 cm (on GPS antenna)

32 cm horizontal transformed to aircraft measuring antenna position
16 cm vertical transformed to aircraft measuring antenna position  

**32 cm** horizontal transformed to aircraft measuring antenna position
**16 cm** vertical transformed to aircraft measuring antenna position

- Measuring Accuracy

## Mobile DGPS reference station
DGPS reference station network
Major aerodromes  (LKPR, LKTB, LKMT, LKKV)
Providing coverage over all CR
Database of coordinates (WGS-84)
Surveyed by Czech Army Topographical Institute
Verified by independent agency
Special WPT database
Computed points
GPS surveyor
Geodetic (D)GPS, OMNISTAR corrections, ± 0.8m , ± 0.02m relative 

- DGPS reference station network
- Major aerodromes  (LKPR, LKTB, LKMT, LKKV)
- Providing coverage over all CR
- Database of coordinates (WGS-84)
- Surveyed by Czech Army Topographical Institute
- Verified by independent agency
- Special WPT database
- Computed points
- GPS surveyor
- Geodetic (D)GPS, OMNISTAR corrections, ± 0.8m , ± 0.02m relative

- Ground support

## RTK successfully used for Flight test up to ILS cat III
Independence of ground assistance - effectivity
Human factor influence reduction.
Visibility independence - better serviceability

Experience with these technologies in ACFT guidance.
Knowledge for future coming satellite technologies
EGNOS
GALILEO

- Independence of ground assistance - effectivity
- Human factor influence reduction.
- Visibility independence - better serviceability
- Experience with these technologies in ACFT guidance.
- Knowledge for future coming satellite technologies
- EGNOS
- GALILEO

- Conclusions