using System.Collections.Generic;
using System.Collections.ObjectModel;
public static class CrewStatus
private static List<string> _validStatuses = new List<string>{ "incoming", "cleared", "en-route", "arrived", "reporting", "off duty", "not available" };
public static ReadOnlyCollection<string> ValidStatuses = new ReadOnlyCollection<string>(_validStatuses);
public static void Main()
string status = "off duty";
Console.WriteLine(CrewStatus.ValidStatuses.Contains(status.ToLower().Trim()));