public async override Task Insert <T>(T item)
 {
     if (typeof(T) == typeof(Aircraft))
     {
         var aircraft = CreateCopy(item as Aircraft);
         InternalData.AddAircraft(aircraft);
     }
     if (typeof(T) == typeof(Airfield))
     {
         InternalData.AddAirfield(CreateCopy(item as Airfield));
     }
     if (typeof(T) == typeof(AcType))
     {
         InternalData.AddAcType(CreateCopy(item as AcType));
     }
     if (typeof(T) == typeof(Flight))
     {
         InternalData.AddFlight(CreateCopy(item as Flight));
     }
 }