Based on information I have received from Mikrokopter: 1. Please check the firmware that you are using for your BL-Ctrl's on the Double Quadro boards. Please do NOT fly with versions 1.00 or 1.02. As has been posted elsewhere, there is the potential for motor restart and current spike problems which may cause crashes. PLEASE UPGRADE THE BL-CTRL FIRMWARE TO 1.08 BEFORE YOUR NEXT FLIGHT if you are not already at version 1.08. The upgrade instructions are here: http://wiki.mikrokopter.de/BL_V3Update You will need to translate them into English using Google Translate or your Web Browser. EDIT: Holger points out that the English instructions are here: http://wiki.mikrokopter.de/en/BL_V3Update There are additional comments here: http://www.multirotorforums.com/archive/index.php/t-18960.html 2. Flight Control Board firmware: The current version is version 2.08 -- please consider upgrading to this. You will need to upgrade to matching MK Tool and Navigation Control board firmware -- but the MK Tool app can guide you on this. If you choose not to upgrade to 2.08 then please double check you are not using FC Version 2.06a, b, c, d, or e -- please upgrade to 2.06f -- this version corrects a problem EDIT: with current spikes during motor start. where some users found the copters would climb rapidly after take off. Please consider this a mandatory upgrade. Thanks Andy.