A combustor for a gas turbine engine having an annular combustion chamber, comprising: a bulkhead disposed at a forward end of the annular combustion chamber, the bulkhead having a radial expanse and a circumferential expanse; a plurality of main fuel injection and air swirler assemblies opening through the bulkhead for admitting fuel and air into the annular combustion chamber, the plurality of main fuel injection and air swirler assemblies disposed in a circumferential ring extending about the circumferential expanse of the bulkhead; a plurality of pilot fuel injection and air swirler assemblies opening through the bulkhead for admitting fuel and air into the annular combustion chamber, the plurality of pilot fuel injection and air swirler assemblies interspersed amongst and disposed in the circumferential ring of main fuel injection and air swirler assemblies; characterised in that: the air swirlers of the plurality of main fuel injection and air swirler assemblies are adapted to impart a lower level of swirl to air passing therethrough relative the air swirlers of the plurality of pilot fuel injection and air swirler assemblies; and in that each of the plurality of main fuel injection and air swirler assemblies includes a fuel injection nozzle and an air swirler disposed about an end of the nozzle, the air swirler having a radially inner conical surface, the nozzle configured to inject fuel onto the radially inner conical surface of the air swirler, the inner conical surface configured to receive the fuel from the nozzle and to form a fuel film, the air swirler configured to impart a swirl to the air passing therethrough that shears off the fuel film from the radially inner conical surface of the air swirler. a bulkhead disposed at a forward end of the annular combustion chamber, the bulkhead having a radial expanse and a circumferential expanse; a plurality of main fuel injection and air swirler assemblies opening through the bulkhead for admitting fuel and air into the annular combustion chamber, the plurality of main fuel injection and air swirler assemblies disposed in a circumferential ring extending about the circumferential expanse of the bulkhead; a plurality of pilot fuel injection and air swirler assemblies opening through the bulkhead for admitting fuel and air into the annular combustion chamber, the plurality of pilot fuel injection and air swirler assemblies interspersed amongst and disposed in the circumferential ring of main fuel injection and air swirler assemblies; characterised in that: the air swirlers of the plurality of main fuel injection and air swirler assemblies are adapted to impart a lower level of swirl to air passing therethrough relative the air swirlers of the plurality of pilot fuel injection and air swirler assemblies; and in that each of the plurality of main fuel injection and air swirler assemblies includes a fuel injection nozzle and an air swirler disposed about an end of the nozzle, the air swirler having a radially inner conical surface, the nozzle configured to inject fuel onto the radially inner conical surface of the air swirler, the inner conical surface configured to receive the fuel from the nozzle and to form a fuel film, the air swirler configured to impart a swirl to the air passing therethrough that shears off the fuel film from the radially inner conical surface of the air swirler. the air swirlers of the plurality of main fuel injection and air swirler assemblies are adapted to impart a lower level of swirl to air passing therethrough relative the air swirlers of the plurality of pilot fuel injection and air swirler assemblies; and in that each of the plurality of main fuel injection and air swirler assemblies includes a fuel injection nozzle and an air swirler disposed about an end of the nozzle, the air swirler having a radially inner conical surface, the nozzle configured to inject fuel onto the radially inner conical surface of the air swirler, the inner conical surface configured to receive the fuel from the nozzle and to form a fuel film, the air swirler configured to impart a swirl to the air passing therethrough that shears off the fuel film from the radially inner conical surface of the air swirler.