Airfoil with impingement cooling of a large fillet

A gas turbine engine blade (11) has a relatively large fillet (18) to improve the characteristics of the air flow thereover. The fillet (18) has a thin wall which, together with an impingement rib (35), defines a fillet cavity (24) therebetween, and cooling air is provided to flow through impingement holes (26) in the impingement rib (3 5) and impinge on the rear surface (27) of the fillet (18). The impingement holes (26) are elongated in cross sectional shape with their elongations being oriented in a direction generally transverse to a radial direction.