A gas turbine engine having a combustor, turbine and transition duct to channel hot gas from combustor to turbine. The transition duct has an internal surface on which the hot gas impinges causing a varying temperature profile. A thermal barrier coating is located on the internal surface having a first and second thermal barrier coating patch. The first patch having a first thickness located on the internal surface and within a first area subject to a higher temperature than an uncoated part and bounded by a first isotherm of a first temperature. The second patch having a second thickness located on the internal surface and within a second area subject to a higher temperature than the uncoated part and bounded by a second isotherm of a second temperature. The second temperature is higher than the first temperature and the second thickness is thicker than the first thickness.