var BG = xd.Descendants(ns + "PricedItineraries").Elements(ns + "PricedItinerary").Select(o => string.Join(",", o.Elements(ns + "AirItinerary")
                .Elements(ns + "OriginDestinationOptions").Elements(ns + "OriginDestinationOption")
                .Elements(ns + "FlightSegment").Attributes("ArrivalDateTime"))).ToList<string>();