An airfoil (62; 162) for a gas turbine engine comprising: an airfoil (62A; 162A) section extending in a radial direction from a platform section, extending in a chordwise direction between a leading edge (62LE; 162LE) and a trailing edge (62TE; 162TE), and extending in a thickness direction between a pressure side and a suction side that join together at the leading (62LE, 162LE) and trailing edges (62TE; 162TE; wherein at least one of the airfoil section (62A; 162A) and the platform section include a wall, the wall extending between an internal wall surface and an external wall surface (162SE; 260SE; 460SE; 660SE), and the internal wall surface bounding an internal cavity; wherein the wall includes a plurality of pedestals (176; 276; 476; 676) having adjacent pedestals (176; 276; 476; 676) extending from the external wall surface (162SE; 260SE; 460SE; 660SE) to establish a respective cooling passage (170; 270; 470; 570; 670), and the cooling passage (170; 270; 470; 570; 670) includes an inlet (172; 272; 472) and an outlet (174; 274; 474), the inlet (172; 272; 472) coupled to the internal cavity along the internal wall surface, and the outlet (174; 274; 474) along the external wall surface (162SE; 260SE; 460SE; 660SE); wherein the adjacent pedestals (176; 276; 476; 676) are dimensioned such that the adjacent pedestals (176; 276; 476; 676) taper inwardly from the inlet (172; 272; 472) in a first direction towards the outlet (174; 274; 474) to establish a throat (178; 278; 578) in the respective cooling passage (170; 270; 470; 570; 670), and the respective passage expands outwardly from the throat (178; 278; 578) in the first direction towards the outlet (174; 274; 474) to establish a diffusion section interconnecting the throat (178; 278; 578) and the outlet (174; 274; 474); and one or more coatings along the external wall surface (162SE; 260SE; 460SE; 660SE) and into the outlet (174; 274; 474) to establish a coated outlet region of the cooling passage (170; 270; 470; 570; 670), characterised in that a minimum cross-sectional area of the cooling passage (170; 270; 470; 570; 670) along the coated outlet region divided by a cross-sectional area of the throat (178; 278; 578) establishes a coated area ratio, and the coated area ratio is greater than or equal to 0.8. an airfoil (62A; 162A) section extending in a radial direction from a platform section, extending in a chordwise direction between a leading edge (62LE; 162LE) and a trailing edge (62TE; 162TE), and extending in a thickness direction between a pressure side and a suction side that join together at the leading (62LE, 162LE) and trailing edges (62TE; 162TE; wherein at least one of the airfoil section (62A; 162A) and the platform section include a wall, the wall extending between an internal wall surface and an external wall surface (162SE; 260SE; 460SE; 660SE), and the internal wall surface bounding an internal cavity; wherein the wall includes a plurality of pedestals (176; 276; 476; 676) having adjacent pedestals (176; 276; 476; 676) extending from the external wall surface (162SE; 260SE; 460SE; 660SE) to establish a respective cooling passage (170; 270; 470; 570; 670), and the cooling passage (170; 270; 470; 570; 670) includes an inlet (172; 272; 472) and an outlet (174; 274; 474), the inlet (172; 272; 472) coupled to the internal cavity along the internal wall surface, and the outlet (174; 274; 474) along the external wall surface (162SE; 260SE; 460SE; 660SE); wherein the adjacent pedestals (176; 276; 476; 676) are dimensioned such that the adjacent pedestals (176; 276; 476; 676) taper inwardly from the inlet (172; 272; 472) in a first direction towards the outlet (174; 274; 474) to establish a throat (178; 278; 578) in the respective cooling passage (170; 270; 470; 570; 670), and the respective passage expands outwardly from the throat (178; 278; 578) in the first direction towards the outlet (174; 274; 474) to establish a diffusion section interconnecting the throat (178; 278; 578) and the outlet (174; 274; 474); and one or more coatings along the external wall surface (162SE; 260SE; 460SE; 660SE) and into the outlet (174; 274; 474) to establish a coated outlet region of the cooling passage (170; 270; 470; 570; 670), characterised in that a minimum cross-sectional area of the cooling passage (170; 270; 470; 570; 670) along the coated outlet region divided by a cross-sectional area of the throat (178; 278; 578) establishes a coated area ratio, and the coated area ratio is greater than or equal to 0.8.