LTHR
Zone 1: Less than 85% of LTHR – 136
Zone 2: 85–89% of LTHR – 136 – 143
Zone 3: 90–94% of LTHR – 144 – 150
Zone 4: 95–99% of LTHR – 151 – 158
Zone 5a: 100–102% of LTHR – 159 – 163
Zone 5b: 103–106% of LTHR – 163 – 170
Zone 5c: More than 106% of LTHR – 170+