Aviation Station Obj-C classes

Download Class source and parsed file
As I mentioned, I needed to build a list of aviation stations for another project I was working on.
So I created two classes to deal with this, and decided to make them public. Don't know if anyone will care, but if you do I've done the grunt work for you and please take advantage of it.

What classes?
I created two classes AviationWeatherStation and AviationWeatherStationCollection.
AviationWeatherStation contains all the data for each airport as listed in stations.txt.
AviationWeatherStationCollection is a simple aggregation of all the AviationWeatherStations, with some utility functions, we'll look at that first.
Class definition.
@interface AviationWeatherStationCollection : NSObject <NSCopying,NSCoding>
NSDate *lastUpdated; // this is the date from the stations.txt file this collection was generated from
NSInteger numberOfStations;
NSMutableArray *stations;
// these two are optional, be prepared for nil
NSString *stateName;
NSMutableArray *stateByStateCollection;

Instance methods with useage.
-(id)copyWithZone:(NSZone *)zone;
Deep copies the current collection.
-(void) createStateCollections:(BOOL)usOnly;
Creates another array of stations, sorted by U.S. state, as a property of this object.
-(AviationWeatherStation *)stationWithICAOID:(NSString *)thisID;
Returns the station that exactly matches the input ICAO code
-(NSArray *)stationArrayWithPartialICAOID:(NSString *)thisID orName:(NSString *)name orState:(NSString *)state;
Partial matching search. Will search for EITHER a partial ICAO code OR a partial airport name OR a partial state. First one hit wins, if there is an ICAO partial code and a partial name, the ICAO code wins for example.
-(NSMutableArray *)stationsWithinDistanceFromStation:(AviationWeatherStation *)station within:(NSInteger)distance;
Pass in a AviationWeatherStation object and a distance (in miles) and an array of stations within that radius will be returned.
@interface AviationWeatherStation : NSObject <NSCopying,NSCoding>
{ NSString *stateName; // optional unless there is no state abreviation
NSString *stateAbbreviation; // might not exist
NSString *stationName;
NSString *ICAO;
NSString *IATA;
NSInteger SYNOPIndex;
double latitude;
double longitude;
NSInteger ELEV;
char METAR;
char NEXRAD;
char aviationFlag;
char upperAirOrWind;
char observationType;
char officeType;
char plottingPriority;
NSString *countryCode;
NSMutableDictionary *refCon; // might not exist. Key-value pairs to provide additional data to
// a station wihtout having to subclass.
// if you generate a AWSPCK key value that you want to share and add things to this dictionary
// please email me the key & value & meaning and I'll include it in this header
// and on the docs page.
// Also, PLEASE maintain any keys that you might find in a file.
// And it's called a refCon becasue I'm old
} -(id)copyWithZone:(NSZone *)zone;
// my dictionary entry for making a station a favorite
// key CKFavorite as an example. Optional, you can certainly pull this code out if you want
-(BOOL) isFavorite;
-(void) setFavorite:(BOOL) yesOrNo;