When I try to book online Maastricht-Brussels Airport, the trip that comes up has a very short connection time (9 minutes) in brussels Nord. There is a later train from brussels Nord to Brussels Airport but that doesn't appear to be an alternative on the online booking. In fact, when I try to book 2 separate trips (Maastricht-Brussels Nord and Brussels Nord-Brussels Airport), it will not let me choose Brussels Airport for the arrival city when the departure city is Brussels Nord. Is it not possible to book Brussels Nord-Brussels Airport online? How do I go about making these reservations? Thank you!
What site are you using to book? Nine minutes is pretty good for a connection time in Belgium....the trains usually run to the second, so there shouldn't be any problem.
As to your second question, it's possible to book Brussel-Noord to Brussel-Aeroport on-line at the Belgian national rail website....you can also book your entire trip there....and print out tickets at home. Total journey price shows as 16 Euro. But, if you do have problems booking that last section, don't worry. There are about 4 trains/hour between Brussels and the airport, and they stop at all three main Brussels stations.
There's no advantage to purchasing advance tickets for inter-city trains in Holland and Belgium, as seat reservations are not possible. Simply purchase your tickets on the day of your journey at the train station.
Echoing the previous poster, trains leave so frequently between these stations (at least two, if not more, an hour between Brussel Nord and the airport), there is no reason to book any of these tickets in advanced. If you miss one train, you rarely have to wait very long for the next, and your ticket is valid all day.