If you’ve boarded a commercial jet in recent decades, odds are high it was a Boeing and even higher that its name followed a peculiar pattern: 737, 747, 777, or maybe the sleek 787 Dreamliner. There’s a rhythmic familiarity to those names, all echoing the “7X7” format. But how did this unique naming convention begin, and why has it endured across decades of aviation innovation?
Boeing, the American aerospace titan, didn’t always label its aircraft this way. Its numbering system originally used blocks of hundreds to distinguish product types, 300s and 400s for propeller aircraft, and 600s for missiles. When jet airliners entered the scene, Boeing reserved the 700 block for them.
The first of these was the iconic Boeing 707, which took its inaugural flight in 1957. One might wonder why it wasn’t simply called the 700. Some speculate that “707” rolled off the tongue better, while others point out a geekier reason: 707 happens to be the first three digits of both the sine and cosine of 45 degrees—a number every engineer knows well. This subtle nod may have highlighted the 707’s swept-wing design, a technological leap at the time, even though the wings were actually swept at 35 degrees, not 45.
As the jet age took flight and captured the imagination of the public, the 707 soared beyond aviation—it became a cultural icon. Jantzen, a swimsuit brand, named its 1957 line after the plane, reflecting just how fashionable Boeing’s jet had become. Realizing the strength of this branding, Boeing leaned into the format. The next aircraft was a 707 variant named the 720, followed by the fully new 727 in 1963. The rest is naming history: 737, 747, 757, 767, 777, and finally the futuristic 787 Dreamliner. Boeing even backfilled a gap with the 717, a jet first flown in 1998.
This consistent naming strategy eventually became Boeing’s signature—a branding anchor that’s nearly synonymous with commercial aviation itself. Changing it now would cause, as the article puts it, “a cultural shock in the aviation world.”
But what happens after the 797?
Boeing has long mulled over a New Middle-Market Airplane (NMA) project, a successor to its aging 757 and 767 lines. If built, it’s expected to bear the name 797, likely the final chapter in the 7X7 sequence. After that, Boeing would be out of numbers… unless it decides to leap into awkward territory with names like “7107,” which admittedly, doesn’t quite have the same ring.
So, what comes next? Will Boeing finally break its cherished naming mold? Or might we one day step aboard a “7A7,” as a playful continuation of the legacy?
