The 400, the most prolific 747 type, first entered service with Northwest Airlines in 1989. It was the fourth iteration of Boeing's popular jumbo, featuring a more advanced flight deck, a lighter build and, perhaps most importantly, a significantly boosted range. The most recent iteration can travel more than 8,000 miles, enabling airlines to fly from North America to Southeast Asia or Australia without stopping to refuel. An extended-range model, which added fuel tanks to the cargo hold, is used exclusively by Qantas. That plane has a nearly 9,000-mile range, which covers the 8,500-mile trek from Sydney to Dallas, Texas (with a fueling stop on the longer westbound return). The Airbus A380 will replace the 747-400ER on that route beginning in September.

During the last three decades, more than 500 747-400s have been built, with British Airways, Lufthansa and United placing some of the largest orders. That latter carrier still operates one of the longest 747 routes, transporting nearly 400 passengers the 7,000 miles from San Francisco to Hong Kong every day. The versatile 777-200 has replaced its aging sibling on many of UA's other long-haul routes, though, offering significantly improved performance and a better passenger experience, with amenities such as more comfortable seats, WiFi and in-flight entertainment.

The 747-400's retirement doesn't mark the end for the entire aircraft line. Boeing's built an extended version, the 747-8, in an attempt to reclaim some of the superjumbo market from Airbus, and Lufthansa has begun operating that higher-capacity plane on routes between Germany and the US. And while carriers like British Airways, Delta and Qantas are phasing out the 747 entirely, other airlines are reassigning their planes to regional service. Thai's 747 travels throughout Asia, for example, and even carries passengers on the one-hour trip from Bangkok to Chiang Mai, while Cathay Pacific continues to operate the type between Hong Kong and regional destinations such as India and Bali.

And while passengers may want to avoid traveling 16 hours on a 747 that excludes power outlets and seat-back TVs, such as those operated by United, getting to fly the quad-engine jet on a short hop is nothing short of a thrilling treat. Even shorter routes will transition to more efficient aircraft over the next few years, but for the time being, you can still experience the original superjumbo on select flights. In the commercial aviation world, there's nothing more exhilarating than traveling in seat 1A, where the curvature at the nose makes it possible to see at a near-forward angle during takeoff and landing. And, if you're lucky enough to be traveling in business class, climbing the stairs up to the exclusive second deck is an experience in and of itself.