The fuel efficiency of a jet depends on several factors, including the type of aircraft, its weight, and the altitude at which it is flying. Generally, larger jets that fly at higher altitudes are more fuel-efficient than smaller jets that fly at lower altitudes.
For example, a Boeing 747-400, one of the largest passenger jets in the world, can achieve a fuel efficiency of around 23 NM/gal when flying at 35,000 feet. In comparison, a Cessna Citation CJ3, a small business jet, can achieve a fuel efficiency of around 18 NM/gal when flying at 30,000 feet.
It's important to note that fuel efficiency is just one of many factors that airlines consider when operating their aircraft. Other factors include speed, range, and passenger capacity.
