Fuel burn remains a top priority for airlines. The metric is ASM/Gallon (or litre outside the US). Airlines want the numerator as high as possible and the denominator as low as possible. This is where upsizing aircraft becomes so attractive. The aircraft's weight rises less than its capacity. But while that may be attractive, adding new generation engines multiplies the impact. Take a look at the chart. We show ASM/Gallon as a KPI for the previous generation and current generation single-aisles in US service. The two generations are shown as the two blue curves. The orange curve is the percentage difference between the two blue curves. [caption id="attachment_99203" align="aligncenter" width="640"] AirInsight[/caption] We last looked at this about half a year ago. CFM reported that LEAP operators were seeing a 15 percent improvement in fuel burn compared to the CFM56. Pratt & Whitney is already pushing much higher. Readers may recall that 16% was the significant promise when these new engines were first launched. We show, using USDOT data, that in the US, the new generation engines perform better than promised in fuel burn terms. Way better. That orange curve exceeds 30%. Not the current engine generation hovers around 100, which seems to be the new ASm/Gallon benchmark. The new engines have indeed run into challenges, especially the GTF. But, in fuel-burn terms, they perform superbly. This was noted by Pratt's CEO, Rick Duerloo, when he said that because the GTF over-delivers in terms of fuel burn, customers are happy to give up some of that for better durability. Fuel Burn By Model The data behind this table comes from the US DOT T2 dataset. The numbers are statistically identical to the results from Skailark. weare confident the numbers reflect the actual performance. [caption id="attachment_99206" align="aligncenter" width="640"] US DOT; AirInsight[/caption] The results are impressive. Although the previous generation has improved, this is primarily driven by airlines pushing 150-seaters to 160 or 170. That drives ASMs up for the same fuel burn. But the real story here is the step change introduced by the new engine technology. The results speak for themselves: a measurable, sustained, and structurally driven improvement in operational efficiency.