Just thought I'd mention that this looks like a cut and paste error in radar.js
acft_1.onload = function() {
off_ac_X[1] = (acft_1.width / 2);
off_ac_Y[1] = (acft_0.height / 2);
//console.log("off_ac_X[1] X=" + off_ac_X[1] + " Y=" + off_ac_Y[1]);
}
Think the third line ought be off_ac_Y[1] = (acft_1.height / 2);