Wires are horribly horrendously ridiculously difficult to see, even in good light. All helicopter pilots know this, since we land off airfield quite a lot, so looking for wires is extremely important. I still remember what I got told on my R22 Safety Course soon after getting my PPL(H) - if it's a brown sticky-uppy thing without leaves on it, it'll have wires attached!!! Always remember that, and fly safe. Thanks for reminding us Deano.