//adds an airliners to the list
 public void addAirliners(StartDataAirliners airliners)
 {
     this.Airliners.Add(airliners);
 }
 //adds an airliners to the list
 public void addAirliners(StartDataAirliners airliners)
 {
     this.Airliners.Add(airliners);
 }