I've had one case in which my Colibi recorded an "engine running" in flight in my ASW-15. I tried several ways to try to duplicate the problem with cockpit noise (side window open, side window vent open, hand out the side window, nose vent full open, high speed flight, gear down, full forward slip, full forward slip with gear down, window open and nose vent full open...) NONE of these produced a noticeable increase in recorded ENL as seen on SeeYou. On the other hand by looking at the ENL trace I can determine pretty accurately when the tow rope was released. Because of this I thought that the noise recorder might be filtered so it only detects noise in the spectrum produced by engines.

I've also had one case in which the Colibri said that ten minutes after I had parked my glider by the trailer I flew five Km. NW and back to the trailer at ground level in twenty seconds. I've completed over three hundred flights with the Colibri and these are the only two anomalous records it's produced and neither one caused a problem with OLC or a badge flight though.