HTTP 505 Error

I am trying to make a GET request to the below listed url which should
return an XML. When I put the compete url in my browser, I get the
intended XML.

http://axml.travelnow.com/external/xmlinterface.jsp?cid=1&resType=air&intfc=ws&xml=<AirSessionRequest
method="getAirAvailability"><AirAvailabilityQuery><originCityCode>MCI</

<destinationCityCode>ATL</
<departureDateTime>11/19/2005 11:00 AM</
<returnDateTime>11/21/2005 10:00 AM</
<fareClass>Y</fareClass><tripType>R</
<Passengers> <adultPassengers>1</adultPassengers></
</AirAvailabilityQuery></AirSessionRequest>

However, when I try to make a request with Net:HTTP I get a
HTTPNotValidError.

Here is what I have:

url = URI.parse('http://axml.travelnow.com')
req = Net::HTTP::Get.new("/external/xmlinterface.jsp?
cid=1&resType=air&intfc=ws&xml=<AirSessionRequest
method="getAirAvailability"><AirAvailabilityQuery><originCityCode>MCI</

<destinationCityCode>ATL</
<departureDateTime>11/19/2005 11:00 AM</
<returnDateTime>11/21/2005 10:00 AM</
<fareClass>Y</fareClass><tripType>R</
<Passengers> <adultPassengers>1</adultPassengers></
</AirAvailabilityQuery></AirSessionRequest")

    res = Net::HTTP.start(url.host, url.port) {|http|
      http.request(req)
    }
puts res
puts res.body

There error I get is:

HTTPVersionNotSupported # 505