There's an airfield at Oud-Turnhout, used mostly for parachuting and shown as 400 m hard runway. Unfortunately I have no contact details, but you might find out more via
Skydive Flanders. Oud-Turnhout seems to be strangely absent from their list.
There's also a military field EBWE at Weelde a few km north if you prefer 3000 m of tarmac. Belgian AIP contact info for civil use is:
a. Mail:
Belgian air cadets
Hannuitsesteenweg, 350
B-3300 Goetsenhoven
Tel:++32 (0) 16 81 34 41
b. Mail:
CCVW
Walter Geenen
Molenzijde, 69
B - 2330 Merksplas
Tel:++32 (0) 14 65 58 09
Tel:++32 (0) 14 65 62 35 (AD)
• OPR HR HJ
• AFIS: "Weelde Radio" - 120.225 MHz - INFO only, no ATC
• RMK:
The use of the AD is subject to prior permission from the operator.
AD given in concession to the CIV club outside MIL ACT.
See also
http://www.kac.be/ for an email address for Geenen.
I have no personal experience of either place.