public IEnumerable <Person> GetPassengersByFlightNumber(string flightNumber)
        {
            if (string.IsNullOrEmpty(flightNumber))
            {
                throw new HttpResponseException(HttpStatusCode.BadRequest);
            }
            IEnumerable <Person> personList = _PersonProvider.GetPassengersByFlightNumber(flightNumber);

            return(personList);
        }