The (3,2) Neoclassical Tearing Mode (NTM) degrades plasma confinement by providing a region of rapid radial transport about a magnetic island structure in the plasma. As ITER is likely to be metastable to this instability it is important to understand the mechanisms of its triggering. This work is an attempt to address this question through phenomenology and statistical analysis of NTM onset data, exploring pulses both with and without the (3,2) NTM in JET ELMy H-mode plasmas. In addition to sawteeth, fishbone instabilities are observed to trigger NTMs. Both triggering instabilities have similar (1,1) mode amplitudes near the time of the (3,2) NTM onset. However, the NTM triggering does not seem to be related to the size of the magnetic precursor to the sawtooth or fishbone. For sawtooth triggered cases, the NTM probability at low b rises with sawtooth period. Longer sawteeth also tend to have (3,2) NTM onset at the time of the sawtooth crash, while for shorter sawtooth periods (t 0.2s) the onset is more probable during the precursor to the crash. Many of the JET pulses analysed had both (1,1) sawtooth precursor and (1,1) fishbone bursts present at the time of the (3,2) NTM onset. The (1,1) fishbone bursts exhibit a better frequency match for forced reconnection by non-linear three wave coupling to (3,2) and (4,3) NTMs, indicating this instability to be the most likely candidate in any magnetic coupling model of NTM triggering.