Embedded Files
Overview
Overview
In our requirements section (1.1), one requirement is to print an information summary of any requested airport. The printout should include information about the airport, its runways, landing aids and nearby navaids and waypoints. The airport and runway information will come from apt.dat. The trouble with this file is that it is huge; it is 366 MB and contains 10.4 million rows. So for this project, rather than going through the trouble of restructuring this datafile into airport and runway tables, I decided to just write a parser that will scan the file on demand. That is, the user will enter an ICAO code, and the program will scan through the airport data file to pull out the airport and runway information. We will use Cold Bay, Alaska (PACD) as our example airport.
Inspect the File
Inspect the File
Here is the top of apt.dat. It doesn't look as friendly as the earlier files...
Load file and extract rows from target airport
Load file and extract rows from target airport
Let's inspect what we have grabbed so far:
<class 'list'>486
'1 98 0 0 PACD Cold Bay''1302 city Cold Bay''1302 country United States''1302 datum_lat 55.205261111''1302 datum_lon -162.724522222''1302 faa_code CDB''1302 gui_label 3D''1302 iata_code CDB''1302 icao_code PACD''1302 region_code PA'
'120 Linear Feature 36''111 55.19894515 -162.71807075 1''111 55.19869152 -162.71828720''112 55.19869152 -162.71828720 55.19853737 -162.71843852 1''111 55.19854218 -162.71894413 1''115 55.19856252 -162.71932537''120 Linear Feature 35''111 55.19833272 -162.71501771 1''111 55.19835707 -162.71547420 1''112 55.19873612 -162.71594862 55.19901399 -162.71590393'
'1 98 0 0 PACD Cold Bay''1302 city Cold Bay''1302 country United States''1302 datum_lat 55.205261111''1302 datum_lon -162.724522222''1302 faa_code CDB''1302 gui_label 3D''1302 iata_code CDB''1302 icao_code PACD''1302 region_code PA'
'120 Linear Feature 36''111 55.19894515 -162.71807075 1''111 55.19869152 -162.71828720''112 55.19869152 -162.71828720 55.19853737 -162.71843852 1''111 55.19854218 -162.71894413 1''115 55.19856252 -162.71932537''120 Linear Feature 35''111 55.19833272 -162.71501771 1''111 55.19835707 -162.71547420 1''112 55.19873612 -162.71594862 55.19901399 -162.71590393'
So far so good. Moving on to the next step...
Parse basic airport data out of rows
Parse basic airport data out of rows
We can print out some results for inspection. I've highlighted the new values that were extracted.
<class 'dict'>
{'apt_coords': LatLon(55°12′18.94″N, 162°43′28.28″W), 'apt_elev_ft': '98', 'apt_name': 'Cold Bay', 'city': 'Cold Bay', 'country': 'United States', 'icao_code': 'PACD', 'landing_aids': 'unknown', 'navaids': 'unknown', 'region_code': 'PA', 'runways': [], 'search_area': 'unknown', 'waypoints': 'unknown'}
{'apt_coords': LatLon(55°12′18.94″N, 162°43′28.28″W), 'apt_elev_ft': '98', 'apt_name': 'Cold Bay', 'city': 'Cold Bay', 'country': 'United States', 'icao_code': 'PACD', 'landing_aids': 'unknown', 'navaids': 'unknown', 'region_code': 'PA', 'runways': [], 'search_area': 'unknown', 'waypoints': 'unknown'}
Extract Runway Information
Extract Runway Information
Next we parse the runway data and reform it into a dataframe; this dataframe will be stored in the 'runways' entry of our airport_data dictionary.
Inspect the results...
Raw runway data from data file:'100 46.02 1 0 0.00 0 3 0 15 55.22234778 -162.73793381 0 0 3 8 0 0 33 55.19646792 -162.71997198 0 0 2 0 0 0''100 46.02 1 0 0.00 0 3 0 08 55.19917101 -162.73232359 0 0 2 0 0 0 26 55.19801901 -162.70899407 0 0 2 0 0 0'
<class 'pandas.core.frame.DataFrame'>
<class 'pandas.core.frame.DataFrame'>
And here is the runway dataframe we created:
Note carefully:
Note carefully:
In real life, runway lengths are defined with "declared distances" that include dimensions of stopways and clearways. We don't have that level of granularity available in our data. So:
length_m means the physical strip length
Furthermore:
the runway lengths are not in the raw data; we calculated them using the runway threshold coordinates using PyGeodesy
likewise, the true bearing was calculated from the runway threshold coordinates
Lookup available ILS and LOC aids
Lookup available ILS and LOC aids
Now that we have extracted the runway data, we can also check whether these runways have ILS or Localizer landing aids. This data is in the file we looked at in the previous section: earth_nav.dat.
For PACD, a single row was found:
'4 55.194722222 -162.718705556 71 11030 18 52718.405 ICDB PACD PA 15 ILS-cat-I'
This is an ILS aid for RWY 15. After parsing the data out, the resulting table looks like this:
In the next section, we will continue populating our airport dictionary with values needed for our airport summary printout.
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