Transcript Visibility Chain at Regional Airports in the Netherlands Wiel Wauben R&D Information and Observation Technology.

Visibility Chain
at Regional Airports
in the Netherlands
Wiel Wauben
R&D Information and
Observation Technology
Introduction
• KNMI automated the aeronautical observations at regional civil
airports, the so-called AUTO METAR system.
• During the evaluation many questions related to visibility arose.
• It was realized that documentation was scattered between
departments and incomplete; not always verified against current
practices or ICAO requirements and recommendations;
background of deviations were sometimes unclear (requirements
old system or by local agreement?).
 review of visibility chain against WMO 2008, 2010, ICAO 2005,
2006, 2010 and KNMI handbooks, reports and (manufacturer’s)
system documentation, work instructions and configurations.
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Visibility Chain
• Public KNMI internal document
(http://www.knmi.nl/bibliotheek/knmipubIR/IR2012-02.pdf
• Contents
11. Server and client network systems
1. Introduction
2. Sources of meteorological information for users 12. System monitoring and data validation
13. Continuous remote verification
3. Definitions of visibility
14. Derivation of VIS and RVR
4. Causes of visibility reductions
15. Averaging of VIS and RVR
5. Visibility requirements
16. Selection and backup of VIS and RVR
6. Sensors for the measurement of MOR
17. Available VIS and RVR variables
7. Calibration of MOR measurements
18. Meteorological reports
8. Maintenance and effect of contamination
19. Technical infrastructure
9. Sensor locations
20. Data flow
21. Conclusions and recommendations
10. SIAM sensor interface and MUF cascade
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Visibility requirements
MOR (SYNOP Vm, VV)
VIS (METAR/ACTUAL VVVV)
RVR (METAR/ACTUAL VRVRVRVR)
Range (Step)
Accuracy
Range (Step)
Accuracy
Range (Step)
Accuracy
*
0-100 m (10)
0-800 m (50)
50-400 m (25)
±10 m
*
*
100-5000 m (100)
800-5000 m (100)
400-800 m (50)
±25 m
5-30 km (1)
±20 %
5-10 km (1)
±20 %
800-1500 m (100)
±10 %
30-70 km (5)
±20 %
≥10 km
1500-2000# m (100)
±10 %
>70 km
>2 km
*
MOR and VIS accuracy: ±50 m for MOR≤600m; ±10 % for 600<MOR≤1500m; and ±20 % for
MOR>1500m.
#
RVR is reported up to 2000 m at civil airports, but up to 3000 m at military
airbases in The Netherlands (KNMI, 1994). Note that RVR values outside the range
are reported as M0050 and P2000 or P3000.
• WMO (2008) specifies the range of RVR as 10 to 1500 m, whereas
ICAO (2010) recommends a RVR range from 50 to 2000 m.
• The requirements for background luminance are not clearly
stated. Range given in examples and ICAO (2006) only mentions
that an uncertainty of ±10 % is considered acceptable.
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Calibration of MOR
measurements
• A field reference setup of TMM
and FS is used the transfer the
calibration of the TMM to the
FS by means of a so-called
Transmitter ↑
SB receiver ↑
scatter plate.
LB receiver →
FD12P ↑
• Reference restricted to MOR < 1500 m and without precipitation!?
Furthermore the linearity of the sensor over the MOR range is not
verified.
• Background luminance checked via calibrator of manufacturer.
Traceability is currently under review.
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linearity FS
500000
FD12P
HSS
400000
4000
Sum count
300000
FD12P
HSS
3000
Count
200000
100000
2000
1000
0
0
1000
2000
3000
4000
0
5000
6000
0
5000
10000
15000
20000
25000
30000
35000
MOR (m)
6
7000
8000
9000
10000
MOR (m)
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40000
45000
50000
Maintenance and effect
of contamination
• Describes the maintenance
and monitoring of lens
contamination level and the
effect of contamination of the
MOR measurements.
• Flying insects in the measurement volume of the FS sensor can
give significant reductions of the MOR.
• The solution ...
7
? see poster P1(28)!
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Selection and backup
of VIS and RVR
KVS2
RUQC
06
WP Z
Threshold
24
↓↑
↓↑
Z WPU
Threshold
Aiming
point
Aiming
point
KVS1
W = wind
Z = visibility / weather
C = cloud
U = temperature / humidity
P = pressure
Q = radiation
R = precipitation
O = video camera
Technical
room KNMI
• No backup of VIS/RVR at touchdown by FS at other end of RWY in local
MET report (arrival).
• Backup of background luminance is allowed.
• Usage of video camera’s to determine whether VFR conditions apply in
case of sensor failure, but quality images too poor.
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Data flow
VertVis
Cloud
A/VertVis
M/VV
CIBIL
w’w’
RE
MetarPWC
ZMm
ZMa
ZAm
ZAa
Process
ZMm
ZMa
ZAm
ZAa
MetarPWC
Visibility
Vis
Va
Va
Average
Vab
Backup
List
Vprev
Vab
A/Vn
M/Vx
MR/Vn
Backup
BBb
RwName
CodeExtract
BBm
A/Rn1
M/RN1
RVRBoolean
RLL
RVRraw
RVRopt
Average
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RVRBooleanb
RVRBoolean
RVRa
List
MinMax
ZMs
Vis
ZMm
MR/Vn
A/Rn1
M/Vx
ZAsb
A/RVR
RVRBooleanm
Backup
ZMs
ZAs
A/w’w’_MLR
MR/Va
ZAsb
Backup
BB
Sum
MR/w’w’2
RE
IfElse
Median
ZAs
List
Vm
Average
Vis
ZMs
ZAs
M/w’w’
M/RE
12Sec SIAM data
12Sec derived data
1Min data
runway dependent data
local report data
METAR data
proposed change
RVRtend
Average
RVRm
Requested if
RVRBoolean
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RVRn
RVRx
RVRt
MR/RVRa
MR/RVRn
MR/RVRx
MR/RVRt
M/RV1
M/RV1n
M/RV1x
M/RV1t
Conclusions
• The review of the visibility chain was appreciated by internal and external
users.
• During the review some errors in the chain could be pointed out. Some of these
were directly solved, but others require consensus between parties involved
and/or further investigations.
• The recommendations (37) are managed in a spreadsheet. Persons have been
assigned, but items have not yet been prioritised and sometimes their impact is
unclear. Meanwhile new items have been added to the list.
• The maintenance of the document is still under discussion. Inclusion in Dutch
handbook on observations versus coupling to documentation of the underlying
systems, regulations and agreements.
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A useful contribution
• Track changes in WMO / ICAO documentation e.g. used in proposals
for the amendment of Annex 3 and including rationale!
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