This paper gives a new proof for the approximation theorem and the characterisation of normalisability using intersection types for a system with and a -relation that is contra-variant over arrow types. The technique applied is to define reduction on derivations and to show a strong normalisation result for this reduction. From this result, the characterisation of strong normalisation and the approximation result will follow easily; the latter, in its turn, will lead to the characterisation of (head) normalisability.