The most profitable route ever in the whole history of aviation was LON-Lagos for BCAL. The breakeven load factor was around 6%. In the year after the first 747 was introduced on the route (1982-3) BCAL made a net profit on this route of £32 million after all conceivable costs had been thrown at it. That equates to over £6700 per flying hour net profit. That profit was derived after all operating charges, the full cost of the aircraft, a thorough overdosing of overheads and all liabilities such as tax. Beat that if you can!