An inertial particle separator (100;200) configured for communicating with an engine inlet (I) of an aircraft engine having an axis , the inertial particle separator (100;200) comprising: a main duct (22;122) having an inlet fluidly connected to an environment (E) outside of the aircraft engine , and for receiving an airflow (F) from the environment (E) along a first direction (D), and an outlet configured for being fluidly connected to the engine inlet (I), the main duct (22;122) having a first side facing away from the axis and a second side opposed to the first side and facing toward the axis; a bypass duct (24;124) stemming from the main duct (22;122) between the inlet and the outlet , the bypass duct being fluidly connected to the main duct (22;122); and a splitter defined by an intersection of the main duct (22;122) and the bypass duct (24;124), the splitter having a leading edge , characterised in that : the second side of the main duct (22;122) at the inlet extends from the inlet along a second direction (D2) defining an angle (α) of at most 45 degrees with the first direction (D); the main duct (22;122) has a radially outward-most section between the inlet and the splitter , the radially-outward most section having a height (H1) extending from the first side to the second side and a width (W1), and W1/H1≥0.5; a length (G1) from the second side to the first side , from the radially-outward most section along a direction parallel to the second direction (D2), is at least as great as the height (H1) of the main duct (22;122) at the radially outward-most section; a height (H2) of the main duct (22;122) from the leading edge of the splitter to the second side of the main duct (22;122) is at most four times the height (H1) of the main duct (22;122) at the radially outward-most section; and a height (S1) of the bypass duct (24;124) from the first side at an end (P2) of the length (G1) to the leading edge is at least 20% of the height (H1) of the main duct (22;122) at the radially outward-most section. a main duct (22;122) having an inlet fluidly connected to an environment (E) outside of the aircraft engine , and for receiving an airflow (F) from the environment (E) along a first direction (D), and an outlet configured for being fluidly connected to the engine inlet (I), the main duct (22;122) having a first side facing away from the axis and a second side opposed to the first side and facing toward the axis; a bypass duct (24;124) stemming from the main duct (22;122) between the inlet and the outlet , the bypass duct being fluidly connected to the main duct (22;122); and a splitter defined by an intersection of the main duct (22;122) and the bypass duct (24;124), the splitter having a leading edge , the second side of the main duct (22;122) at the inlet extends from the inlet along a second direction (D2) defining an angle (α) of at most 45 degrees with the first direction (D); the main duct (22;122) has a radially outward-most section between the inlet and the splitter , the radially-outward most section having a height (H1) extending from the first side to the second side and a width (W1), and W1/H1≥0.5; a length (G1) from the second side to the first side , from the radially-outward most section along a direction parallel to the second direction (D2), is at least as great as the height (H1) of the main duct (22;122) at the radially outward-most section; a height (H2) of the main duct (22;122) from the leading edge of the splitter to the second side of the main duct (22;122) is at most four times the height (H1) of the main duct (22;122) at the radially outward-most section; and a height (S1) of the bypass duct (24;124) from the first side at an end (P2) of the length (G1) to the leading edge is at least 20% of the height (H1) of the main duct (22;122) at the radially outward-most section. <EOS>