1Terminal
The terminal has a restaurant with view, and photos are possible from the building albeit through glass. One has a great overview of the runways and nearby aprons from here.
2Leonardo
A bit further to the south, the Rue de l'Aéroport will get you to the former Agusta facility, now Leonardo, which will appear on your right. There is not a lot of activity here but when there is, it may be very good. Whenever the hangar doors are open you must be able to read the helicopters inside. It is possible to drive all around the facility since there is no direct connection between the airport and this helispot.
3Main cargo south side
The Rue de l'Aéroport runs right along the fence here, bringing most parked aircraft into view. Stop-and-goes are possible but a longer stay with a car is not advised.
4Runway 04R
An excellent spot to log anything flying in or out, and also a good standpoint for photos of traffic on 04R, or vacating runway 22L at the last exit. The view towards TNT is largely obscured by a construction area. There might be room to park a car but be cautious as no-parking rules are strictly enforced.
5Approach 04L/04R am
This spot is close to exit 4 of the A15/E42 motorway (follow direction Flémalle), at the point where there used to be an overfly some ten years ago. The location offers good views on landings on 04R and it can also work for traffic landing on 04L, if any. You may get away with parking your car here.
6Approach 04L/04R evening
Between exit 4 and Fontaine there is a turn-off where cars can often be parked. Walking onto the grassy area to the north of that, one can obtain a good photo spot for evening arrivals.
7Cargo west
The expanding cargo facilities at the airport were most notably built at the south-western end of the airport. The rather new ramp is large enough to accomodate ten wide body freighters. If you continue past the building, there is a small path along the side of the facilities from where you can reach the fence. Although handling equipment on the ramp will usually preclude photograpy, this location can be very useful for number reading when it is very busy on the main ramp, between TNT and the terminal.
8Former military gate
The former shelter area inside the fence is now used for general aviation and sometimes storage of aircraft. You might be able to see some of those from here. The preserved military aircraft have been removed after closure of the base.
9Old taxitrack north side
This dead end road, Rue de Hollogne, from a bend in the main road in Bierset leads to the fence next to a taxi track that has been closed. It offers a limited view on the opposite aprons and the runways 22. For landings on the latter, spot 10 is much better.
10Runway 22L pm
A small hill in Bierset abeam the threshold of 22L offers good views on traffic landing on that runway. With some effort due to the trees and shrubberies, views onto the runway and opposite aprons can also be had. The light is best in the afternoon of course. Walk to the spot from where the approach lights of 22R (so that is the second set of them when coming from the motorway) begin along the N637. Cars can usually be parked at turnouts of the main road.
11Beginning 22L
The roundabout, where exit 3 of the motorway connects to the airport roads and the N604 into the city, also has a cut-off exit where the main road to Bierset was until 2008. Being a construction area as well, possibilities to park here will vary but it can often be done. On the embankments and within walking distance from here, you should be able to find photo spots for traffic landing, taxiing towards 22L and on the adjacent apron. Bringing steps definitely increases your options.
12Taxiway and main cargo north side
Reach this spot on foot, starting at the airport's public car park. Walk by the Park Inn hotel and follow the fence onto the forested hill. In a corner, the view of this side of the largest apron is good for numbers but photography is difficult. Apart from the high fence, the view on the taxi track towards 22L and both runways is excellent here.