Timing difference between the onsets observed by Solar Orbiter and STEREO-A/Wind vs. the difference in their radial distance. The dotted line shows the ideal travel time for radially propagating 55 keV electrons. The solid lines show the ideal travel time assuming the electrons travel along a Parker spiral (v_sw = 250 km s⁻¹), with various constant pitch-angles ranging from of 0° to 89°.