For the first time Hans visited Leeuwarden AB (NL) as an aircraft-spotter in August 1967. In later years he came back several times. Needless to say it never was easy to picture aircraft in their landing-pattern and at other locations outside the fences !
Also in the case of announced squadron-rotations it was not certain beforehand if there would be any flying-activities on the day he chose to be present .
On the occasion of the 65th anniversary of the R.Netherlands Air Force the annual Open Days in 1978 were held at Deelen AB ; Hans en Frank took a number of pictures there just to give you an impression ; amongst others the presence of the RAF Avro Vulcan and two USAFE F-111’s was significant.