Advanced Failsafe Options for Rotorcraft



Following on from the work put in by the BMFA technology special interest group, we now have approval from the CAA for the use of advanced failsafe options on rotorcraft.


Previously the requirement to use throttle closed or idle on loss or corruption of signal has applied to all model aircraft, however it has been clear for some time that this requirement does not suit all aircraft, particularly multicopters, and the ability to utilise the functionality that many of these aircraft now have as standard presents the opportunity for a number of more desirable outcomes in the event of a loss of controlling signal.


The new wording provides three options that can be chosen to reflect the systems available, these are outlined below, ultimately these will feature in the CAA document CAP 658 but in the interim there will be the opportunity to refine the wording as necessary to reflect the practical application.


Level 1


Rotorcraft with no electronic stability or programmable flight control capability.


Failsafe to be programmed to move throttle to idle or closed position on loss or corruption of the controlling signal, as per current requirements set out in CAP658.


Level 2


Rotorcraft with electronic stability capability but no programmable flight control capability.


Failsafe to be programmed to initiate an immediate hover followed by a controlled descent on loss or corruption of the controlling signal.


Level 3


Rotorcraft with electronic stability and programmable flight control capability.


Failsafe to be programmed to initiate a “loiter” at the point of signal loss or corruption, followed by a return to launch position on continued loss or corruption of the controlling signal after a predetermined time period, at a set altitude above launch position, followed by a controlled descent.


This level requires careful consideration and robust practices to ensure a lawful and safe return to the launch position on the triggering of the failsafe function.

Level 3 rotorcraft must only be made “live” once out on the flight line and this location must be confirmed as the RTH point prior to the commencement of any flight.


Clearly the most significant benefit is the opportunity to programme a controlled descent or a return to home as a lawful option, whilst we are aware that many flyers have been using this option for sometime it is now recognized by the CAA as lawful alternative to the previous failsafe requirements.

Please be aware that for fixed wing aircraft the requirements are unchanged and failsafe activation should bring the throttle to idle or off.