Originally Posted by LondonElite

First of all, you don't have a connection, you have two separate tickets. This means that, in theory, if your IB flight is late/cancelled, you risk losing the entire QR ticket as you were a no-show. At best you are at QR's mercy, and I wouldn't expect much. If you don't have time to collect your bags because of a late arrival, your luggage will spin around at the IB carousel until it is picked up for storage. You will need to contact MAD airport to have your bags forwarded to you (remember IB has no idea about your QR flight, and IB's responsibility is only to get your luggage to MAD). This will not be uncomplicated and inexpensive. These are the risks of separate tickets. You should seriously consider hand-baggage only. That reduces at least one of the risks.