Figure 41: Merge activity diagram (see also Figure 42, Figure 43 and Figure 44).

Flight Headers and
Legs Loaded

Figure 43: Flight legs assessment activity diagram.

Figure 46: Schedule data (Back Aviation) import diagram.

Figure 49: Delete flights for region activity diagram. Figure 50: Insert flights for region activity diagram.

for all Airports in region...

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The database contains a comprehensive coverage of movements for the ECAC area and North America where ATC data were available. In the case of the rest of the world, which relied upon schedule data, gaps are expected. Significant inputs such as the creation of a FLUID number and OID were made for avoiding double-counting flights. However, uncertainties due to the absence or double counting of flights are unavoidable. These uncertainties are difficult to estimate as no source was found to estimate the total number of flights in the world. As mentioned by Attilio Costaguta, Chief of ICAO statistics section:
“While in terms of revenue-tonne kilometres, ICAO has a fairly good coverage, this is not the case for aircraft movements. Data for smaller regional or domestic airlines are generally not submitted to ICAO. Thus the number of departures shown may be significantly smaller than those which actually took place.”
In order to assess the uncertainties present in the inventory, a qualitative assessment was done and is summarized in Table 47. It shows the dependencies, relationships, limitations and assumptions made for each modelling steps.

Table 47: Dependencies, relationships, limitations and assumptions made for each modeling steps (referring to Figure 12).

Modeling steps  Dependencie s  Relationships  Limitations  Assumptions 
Import of AMOC headers  AMOC traffic.txt file  -Airport table - Aircraft table  Capacity of the simulator that generates AMOC traffic.txt file  Data generated are representative of all flight plans registered in the ECAC area 
Import of ETMS headers  ETMS flight.txt file  -ETMS airport table - Aircraft table  Data generated are representative of all flights for North America 
Update of maximum stop time  Lack of arrival time for AMOC data  Use of last event_time 
Import of AMOC legs  AMOC headers and AMOC flight.txt file  OID that makes the link between AMOC headers and legs  Capacity of the simulator that generates AMOC flight.txt file 
Import of ETMS legs  ETMS headers and ETMS flight_chord.t xt file  OID that makes the link between ETMS headers and legs 

Merge of AMOC and ETMS  Consistency check  - Data missing in fields -Rounding of the event-time to the minute -Trajectory kinks due to erroneous speed and flight level 
Assessment  - Variation of the number and distribution of the aircraft position along the trajectory according to the sources - Criteria defined for assessing the duplication of flights 
Import of schedule data headers  Schedule data recorded in Back Aviation database  - Airport table - Aircraft table - Airline table   Data generated are representative of all scheduled and commercial flights declared by airlines in the world 
Import of schedule data legs 
Existing trajectory  Merge of AMOC and ETMS data  - Quality of the existing trajectory 
Profiles and waypoints  -ETMS headers and legs -CARAT (NIMA data)  - Aircraft table - List of city-pairs (AMOC, ETMS, Back Aviation) - Airport table  - Representatives of a week of traffic (February 2002) - Shortest trajectory created by CARAT, not necessary the trajectory used - Aircraft grouping system  Air traffic management conditions applied to air traffic in the rest of the world. 
　
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