The Boeing 707 and 767-300 have a similar ranges yet the 767-300 can carry a larger payload. Although they look the same what are key innovations which allow the 767 to have such lower operating costs per seat mile

I hate to say it, but the Boeing 707 and the 767-300 look nothing like each other. They are two very different aircraft. The technological advances that occurred between the design of the 707 and the 767 are numerous.

The materials used to build the aircraft, the flight controls, computer technology, and especially the engines are very different. There is not necessarily one innovation that sets them apart and makes the 763 more economical. I could write for pages in comparing the engines alone. I could also write a book on the differences in the four person crew of the 707 versus the two person crew of the 763.

I sort of draw this conclusion, trying to compare a 707 and a 763 is like comparing my 97 chevy cavalier to an old 57 chevy. They are both cars, but 40 years of technological advances are at work in my 97. Compare the instrument panels, engine blocks, and technology of both of these cars. The same goes with the jet comparison, both are jets, both have basic flight controls, but the advancements between them are amazing.

Bascially three things:

1) Composite materials instead of metal.

2) Greatly miniturized electronics.

3) Much better engines.

1) I believe that at least 1/3rd or more of the entire 767 is made of very lightweight composite materials instead of metal and this greatly reduced the weight of the aircraft.

2) When you compare avioniics of the 707 with the 767 it's like comparing their first cell phones to those of today. Minituriztion of electronic components has greatly increased reliability and capability while also reducing weight.

3) The old Pratt & Whitney J-57s that powered the 707 could put out around 11,000 lbs. of trust while the engines of the 767 are putting out almost 4-times that amount of thrust, each! These engines do this yet there are fewer overall parts; they are far more fuel-effecient as you can see. The ole 707 engines, if you put your hand inside the exhaust nozzle you'd draw back a hand covered with soot and oil. But do the same thing with the engine of a 767 and it's virtually clean.