This week is the deadline for Delta Air Lines frequent flyers to buy their way onto the last flight of the 747-400 farewell tour, a late December flight from Atlanta back home to the Twin Cities.

As of my last check, the bid stood at 211,000 Delta SkyMiles for a pair of seats and two tickets to the post-flight hangar party.

It seems awfully tempting to jump in on this offer. Sure, it’s just the retirement of a commercial airplane, but there never was anything ordinary about the 747. And there will certainly be nothing left like it in American aviation when it’s gone.

Even if the term “747” means nothing to you, if you spot one in the air, you would recognize it as a very special plane. A genuinely beautiful design, it’s got a distinctive hump over the front part of the airplane along with four big engines slung below its wings.

The plane is such an icon that even the emoji of little jetliners on my iPhone keyboard are of the 747.

The famous hump originated in its early development in the 1960s; what became the 747 had some design traits of a military transport plane. Boeing designers needed to fit a big cargo door on the nose of the plane to get heavy equipment in and out, so they put the so-called flight deck for the pilots out of the way on top of the plane.

The hump remained in the design of Boeing’s new airliner. Boeing’s thinking was that the 747 might not be long-lived as a passenger jet anyway because premium air travel would get taken over by much faster supersonic jets and 747s would get turned into freighters.

Instead, Boeing delivered about four times as many 747s as it initially thought it could sell and the 747 has long outlasted the supersonic Concorde in passenger ­service.

The 747 wasn’t just big. It changed the industry.

The most successful jet of the era that preceded the 747’s 1970 launch was the Boeing 707. While that plane opened the possibility of practical intercontinental travel, 707s gave fliers a relatively cramped flight in a ­narrow plane at a price that was not at all affordable.

In the spacious and efficient 747, a widebody seating more than twice as many people, international air travel became accessible for a broad cross-section of ­business people and tourists.

Lots of air carriers bought these big planes, some just for the prestige of having their flags fly on their own Queen Mary liners. Atlanta-based Delta operated a handful of them in the 1970s, but found the planes too big for its route structure and got rid of them.

It’s fitting that the final stop in the farewell tour is Minneapolis-St. Paul International Airport because when Delta talks about its 747s long tradition of reliable service, it’s really referring to their use by Eagan-based Northwest Airlines, which merged into Delta in 2008.

The 747-400s Delta is retiring now were first put into service by Northwest nearly 30 years ago. At the time, the 747-400 represented a technological leap from previous versions, familiar on the outside but with many improvements under the skin. The new 400s included a “glass cockpit” of electronic displays and other technology along with a big jump in fuel efficiency.

Before the 747-400, Northwest’s older 747s flying to and from Asia used to leave some seats empty to cut weight so they would have enough fuel for the long trips. The new planes had no such problem and could be loaded with more than 400 passengers.

The 747-400 was also the plane that Northwest used in the Pacific to open up new routes, because having the newest and most efficient jet in the air gave Northwest an advantage to push beyond Tokyo and Hong Kong to places like Bangkok and Guangzhou.

But that was in the 1990s. The industry has since changed a lot, both with the broad adoption of smaller two-engine jets for long routes and more point-to-point flying rather than relying on big planes flying in and out of huge hub airports.

Delta has selected the new Airbus A350-900 as its fleet flagship on long routes to Asia, flying its first revenue flight with a new A350 around Halloween. The outside of this twin-engine plane is unremarkable. But inside it features several different service levels, including 32 of the carrier’s innovative Delta One premium seats, each a little micro stateroom with a privacy door.

Delta has said the retirement of the 747 in favor of newer designs like the A350 will allow the airline to go from being the highest-cost provider to the Pacific to the lowest.

Even though the case for moving on from the 747 is obviously solid, those of us who have flown a lot of miles will miss seeing this elegant old plane at airports and in the sky.

Even savvy travelers probably don’t find it easy to tell which of the two-engine competitors now sending the 747s to the boneyard they have just boarded, maybe not until reading the manufacturer and model number on the safety card fished out of the seat pocket. These planes seem that interchangeable.

So here’s a prediction: When it comes time to retire Delta’s A350s, it won’t occur to anybody to throw it a ­farewell party.