Gas turbine engine for aircraft including: engine core including turbine, compressor, and core shaft connecting turbine to compressor; fan located upstream of engine core, including plurality of fan blades; gearbox receives input from core shaft and outputs drive to fan shaft to drive fan at lower rotational speed than core shaft; and fan shaft mounting structure arranged to mount fan shaft within engine. Fan shaft mounting structure includes at least two supporting bearings connected to fan shaft. Gearbox's output is at gearbox output position and fan's input is at fan input position. First bearing separation distance is defined as axial distance between input to fan and closest bearing of at least two supporting bearings in rearward direction from fan. First bearing separation ratio of: the ⁢ ⁢ first ⁢ ⁢ bearing ⁢ ⁢ separation ⁢ ⁢ distance ⁢ ⁢ ( d 1 ) the ⁢ ⁢ axial ⁢ ⁢ distance ⁢ ⁢ between ⁢ ⁢ the ⁢ ⁢ fan ⁢ ⁢ input ⁢ ⁢ position and ⁢ ⁢ the ⁢ ⁢ gearbox ⁢ ⁢ output ⁢ ⁢ position ⁢ ⁢ ( d 4 ) is greater than or equal to 1.6×10−1, and the axial distance between the fan input position and the gearbox output position (d4) is greater than or equal to 0.43 m.