The plane was going anyway, so my flying was energy-neutral.

This is false for two reasons. First, your extra weight on the plane
requires extra energy to be consumed in keeping you up. Second, airlines
respond to demand by flying more planes.

Notes and further reading

page no.

272Boeing 747. Drag coefficient for 747 from Other 747 data from [2af5gw]. Albatross facts from

Real jet engines have an efficiency of about ε = 1/3. Typical engine efficiencies are in the range 23%–36% [adg.
]. For typical aircraft, overall engine efficiency ranges between 20% and
40%, with the best bypass engines delivering 30–37% when cruising [
]. You can’t simply pick the most efficient engine however, since it may be heavier (I mean, it may have bigger mass
per unit thrust), thus reducing overall plane efficiency.

277The longest recorded non-stop flight by a bird...
New Scientist 2492. “Bar-tailed godwit is king of the skies.” 26 March, 2005.
11 September, 2007: Godwit flies 11 500 km non-stop from Alaska to New Zealand. [2qbquv]

278Optimizing hop lengths: the sweet spot is when the hops are about 5000 km long. Source: Green (2006).

280Data for a passenger-carrying catamaran. From [5h6xph]: Displacement (full load) 26.3 tons. On a 1050 nautical mile
voyage she consumed just 4780 litres of fuel. I reckon that’s a weight-transport-cost of 0.93 kWh per ton-km. I’m
counting the total weight of the vessel here, by the way. The same vessel’s passenger-transport-efficiency is roughly
35 kWh per 100 p-km.

281The Lun ekranoplan. Sources: [4p3yco], (Taylor, 2002a).

Further reading: Tennekes (1997), Shyy et al. (1999).