My personal experience with fuel tankering, were my years flying ACMI B-707 and DC-8 based in Jeddah for Saudia in the early 1980s... Particularly for the European DC-8 cargo flights to/from Jeddah.
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Operating cargo flights, we were as a rule, always empty, no payload, out of Saudi Arabia. As a matter of fact, I recall having full tanks on all flights to Europe, our only concern were the max landing weight. Fuel reserves, bad weather, low visibility in Europe, we never were concerned, we could hold for hours, and use Amsterdam as Rome alternate...
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The Saudi culture "our jet fuel is cheap" even was common for short local flights, domestic or even international, to gain time, and for convenience. We would load a 707 or DC-8 with sufficient fuel for 3 or 4 stops without refueling for some passenger flights. Shut-down engines nš 1 and 4 for taxi on arrival, that procedure did not exist... What a waste.
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Outside of the aviation subject, I remember buying gasoline for my car, an old Chevrolet Impala in Jeddah. They charged your tank fill-up by "car size" regardless of how many liters you actually bought. A big car, Chevrolet, was 20 Riyals, a small car, i.e. Toyota, was 15 Riyals...
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Happy contrails