A method for operating a wind turbine , the method comprising: calculating, via a processor , one or more blade root loads comprising a blade root resultant moment of at least one rotor blade of the wind turbine ; estimating , via the processor , a span-wise loading of the rotor blade based at least partially on the one or more blade root loads; determining , via the processor , a deformation margin of the rotor blade based at least partially on the span-wise loading and one or more estimated deformations occurring on the rotor blade ; and controlling , via a processor , the wind turbine based on the deformation margin, and wherein calculating the blade root load of at least one rotor blade of the wind turbine further comprises: measuring, via one or more sensors, a plurality of operating parameters of the wind turbine ; estimating an out-of-plane and in-plane force acting on the rotor blade based at least partially on the plurality of operating parameters; determining an application point of the out-of-plane and in-plane force on a span of the rotor blade ; estimating an out-of-plane moment of the rotor blade based at least partially on the out-of-plane force and the out-of-plane application point; estimating an in-plane blade moment of the rotor blade based at least partially on the in-plane force and the in-plane application point; and calculating the blade root resultant moment acting on the rotor blade based at least partially on the out-of-plane moment and the in-plane moment. calculating, via a processor , one or more blade root loads comprising a blade root resultant moment of at least one rotor blade of the wind turbine ; estimating , via the processor , a span-wise loading of the rotor blade based at least partially on the one or more blade root loads; determining , via the processor , a deformation margin of the rotor blade based at least partially on the span-wise loading and one or more estimated deformations occurring on the rotor blade ; and controlling , via a processor , the wind turbine based on the deformation margin, and wherein calculating the blade root load of at least one rotor blade of the wind turbine further comprises: measuring, via one or more sensors, a plurality of operating parameters of the wind turbine ; estimating an out-of-plane and in-plane force acting on the rotor blade based at least partially on the plurality of operating parameters; determining an application point of the out-of-plane and in-plane force on a span of the rotor blade ; estimating an out-of-plane moment of the rotor blade based at least partially on the out-of-plane force and the out-of-plane application point; estimating an in-plane blade moment of the rotor blade based at least partially on the in-plane force and the in-plane application point; and calculating the blade root resultant moment acting on the rotor blade based at least partially on the out-of-plane moment and the in-plane moment. measuring, via one or more sensors, a plurality of operating parameters of the wind turbine ; estimating an out-of-plane and in-plane force acting on the rotor blade based at least partially on the plurality of operating parameters; determining an application point of the out-of-plane and in-plane force on a span of the rotor blade ; estimating an out-of-plane moment of the rotor blade based at least partially on the out-of-plane force and the out-of-plane application point; estimating an in-plane blade moment of the rotor blade based at least partially on the in-plane force and the in-plane application point; and calculating the blade root resultant moment acting on the rotor blade based at least partially on the out-of-plane moment and the in-plane moment. <EOS>