A machine-implemented method (150; 400) for determining a spatial orientation of a body (202; 302), the method comprising: receiving (152; 402), by receiving equipment located with the body (202; 302), at least three sets of electromagnetic signals, each of the received sets of electromagnetic signals having been transmitted by a different one of at least three separate transmitters (106; 204; 304; 354) at different locations; detecting (154; 406), for each one of the received sets of electromagnetic signals, partial directional information that partially defines a direction from the body (202; 302) to the transmitting transmitter(106; 204; 304; 354) from which the set of electromagnetic signals was received, the detected partial directional information comprising a first one angle of two angles that fully define an arrival direction from which the body (202; 302) received the set of electromagnetic signals in relation to a body frame (312; 356), the detected partial directional information not including a second one of the two angles that fully define the arrival direction; and said method (150; 400) being characterized in that it further comprises: determining (158; 414) the spatial orientation of the body (202; 302), including yaw, pitch, and roll angles relative to a navigation frame, using the detected partial directional information for each one of the received sets of electromagnetic signals, detecting, for each one of the received sets of electromagnetic signals, a rate of change of partial directional information, the detected rate of change of partial directional information comprising a rate of change of the first one angle of two angles that fully define the arrival direction from which the body (202; 302) received the electromagnetic signal set in relation to the body frame (312; 356); and determining (160; 408) an angular rate of change of the spatial orientation of the body frame (312; 356) with respect to the navigation frame, wherein the determining includes using the detected rate of change of partial directional information for each one of the received sets of electromagnetic signals and the determined spatial orientation. receiving (152; 402), by receiving equipment located with the body (202; 302), at least three sets of electromagnetic signals, each of the received sets of electromagnetic signals having been transmitted by a different one of at least three separate transmitters (106; 204; 304; 354) at different locations; detecting (154; 406), for each one of the received sets of electromagnetic signals, partial directional information that partially defines a direction from the body (202; 302) to the transmitting transmitter(106; 204; 304; 354) from which the set of electromagnetic signals was received, the detected partial directional information comprising a first one angle of two angles that fully define an arrival direction from which the body (202; 302) received the set of electromagnetic signals in relation to a body frame (312; 356), the detected partial directional information not including a second one of the two angles that fully define the arrival direction; and said method (150; 400) being characterized in that it further comprises: determining (158; 414) the spatial orientation of the body (202; 302), including yaw, pitch, and roll angles relative to a navigation frame, using the detected partial directional information for each one of the received sets of electromagnetic signals, detecting, for each one of the received sets of electromagnetic signals, a rate of change of partial directional information, the detected rate of change of partial directional information comprising a rate of change of the first one angle of two angles that fully define the arrival direction from which the body (202; 302) received the electromagnetic signal set in relation to the body frame (312; 356); and determining (160; 408) an angular rate of change of the spatial orientation of the body frame (312; 356) with respect to the navigation frame, wherein the determining includes using the detected rate of change of partial directional information for each one of the received sets of electromagnetic signals and the determined spatial orientation. determining (158; 414) the spatial orientation of the body (202; 302), including yaw, pitch, and roll angles relative to a navigation frame, using the detected partial directional information for each one of the received sets of electromagnetic signals, detecting, for each one of the received sets of electromagnetic signals, a rate of change of partial directional information, the detected rate of change of partial directional information comprising a rate of change of the first one angle of two angles that fully define the arrival direction from which the body (202; 302) received the electromagnetic signal set in relation to the body frame (312; 356); and determining (160; 408) an angular rate of change of the spatial orientation of the body frame (312; 356) with respect to the navigation frame, wherein the determining includes using the detected rate of change of partial directional information for each one of the received sets of electromagnetic signals and the determined spatial orientation.