| I'm trying to correct the implied claim repeated in this thread that the ideal descent can be used to model every descent. Oddly enough, nobody asked that question. I'm not saying that a continuous descent is actually guzzling gas like crazy. Well, at least you're admitting as much. For a trip segment, takeoff and climbout are the initial high-fuel-flow phase. Note that LTO (landing and take-off) data are based on flight segments at and below 3,000 ft. AGL, which is 1/10 or less of cruise height of FL30 -- FL40. See Fig. 1 of your reference. The LTO data (limiting climbout / descent phases to <= 3000ft) are relevant to local emissions concerns near airports, the focus of the paper, but not to total fuel / emissions of an entire aircraft flight profile as we're discussing here, and omit 90%+ of the relevant climb/descent characteristics. As discussed in the paper. Figure 2. also provides a strong clue as to why the LTO data show lower total fuel use in the approach vs. climbout phases, again, <=3000 ft: the aircraft monitored are spending 2-5x longer in the approach phase. That is, they're climbing out steeply, with very high fuel-flow rates, whilst they're descending slowly (and hence, spending more total time <=3000 ft) at a much lower fuel-flow rate. Again: you're wrong, given your own cited reference. https://www.mit.edu/~hamsa/pubs/ICRAT_2014_YSC_HB_final.pdf |