public class LineInfo
{
    public static string ArrivalDate { get; set; }
    public static string ArrivalFlightNumber { get; set; }
}

public static class BufferInfo
{
    private static Dictionary<String, LineInfo> bufferInfo = new Dictionary<String, LineInfo>();

    public static void Assign(string Key, LineInfo lineInfo)
    {
        string myStr = lineInfo.ArrivalFlightCode;

        bufferInfo.Add(Key, lineInfo);
    }
}