Fleet Age Has a Price. Here’s the Data.

Yesterday, we introduced our Fuel Efficiency Index

in a table looking at US airline single-aisle fleets. It provoked some conversation, so we’re going deeper in this post. We’re looking at the big airlines by fleet.

• The Next-Gen Premium: The MAX 8 and MAX 9 show up as hyper-efficient, sitting comfortably up in the 1.14 to 1.29 range.
• The A321neo Reality: Interestingly, American’s and Delta’s A321neo sit right near the industry baseline (~0.98–1.04), while United’s climbs to 1.20+. This perfectly highlights how network routing, stage lengths, or configuration densities change the field efficiency of the exact same airframe type across different operators.
• The Structural laggards: Older, sub-optimal fleet types like Delta’s 717 and the smaller A319s (0.68–0.73) are penalized for their lower seat counts and older engine architectures relative to the massive capacity weights of the global fleet.
• Mergers: Moving the Hawaiian fleet into Alaska Airlines for reporting gives a look at how newer Hawaiian A21Ns perform compared to the previous ex-Virgin America A21Ns at Alaska.

Alaska Airlines

Here we see the impact of Hawaiian’s fleet consolidation.  The 717’s poor FEI drives the colors. It is materially lower than the 737-700 (73G).  The MAX fleet delivers best-in-class FEI. The maligned (at Alaska) A21N is back, and its numbers are at the top. Alaska unloaded the inherited Airbus fleet as fast as it could.

Looking at the last row, you see the negative drag on fleet FEI the 717 has brought.  It’s no surprise to see chatter in the industry about retiring them.