TCAS
some have mentioned TCAS and that it would not be effective in this environment
simply put,placing the TCAS in TA mode might be the way to go. At least you would get an alert, altitude and even though you are not supposed to use the bearings, a bearing idea where to look.
nothing is perfect and it will take a number of steps to improve things.
I DO ASK THIS...ARE there any photos that show the piper's landing light to be illuminated?
Same with the copter?
I always tell my pals who fly in this area to have ALL LIGHTS ON...might save your life!!!!