Aviation is a field with no shortage of eccentrics and dreamers, a not-insignificant number of whom have willed even the wildest-sounding schemes into reality. But for every , Spruce Goose, or moon landing, there are scores of unrealized aircraft occupying some spectacular yet unfortunately imaginary Air and Space Museum of the unbuilt. Thanks to a report from the consulting firm Wright Williams and Kelley, we can now add a converted to the president’s Air Force One to this bonkers, illusory collection.

The firm recently studied the feasibility of replacing the current Air Force One fleet, as reported on February 10th, which consists of two modified Boeing 747-200Bs built in the 1990s, both of which are scheduled to be taken out of service within the next decade. Back in the ancient before-time of December 6th, 2016, President-elect Donald Trump that “Boeing is building a brand new 747 Air Force One for future presidents, but costs are out of control, more than $4 billion. Cancel order!”

The Wright Williams and Kelley report sensibly determined that the best cost-cutting solution for the executive aircraft might just be to replace those grand 747s with a fleet of modified Boeing 737s, which are much smaller and not as tremendous.

But that’s boring. If you’re concerned about the presidential plane’s ability to survive a ground attack while also being fucking awesome and terrifying, then why not just add a passenger cabin and office suite to the B-21, the U.S.’s still-in-development long-range strike bomber?

As one of the contributors to the report told Aviation Week:

“The 747 is a fat radar target, about the size of a B-52...[The B-21] has stealth built in, it’s nuclear-rated and heavily shielded right off the bat. It’s going to be terribly cramped but man, it would be a survivable platform, especially if operated in twos and threes.”

Sorry to be lame, but I’m here to tell you this is a non-starter, for a number of practical reasons.

The B-21 is shrouded in secrecy—it’s widely suspected the plane will be to deliver the 30,000-pound Massive Ordnance Penetrator, but its full intended loadout, and thus its operational parameters, are currently unknown to the general public. The plane likely won’t even enter service until the mid-2020s, assuming the thing . Optimistically, the current Air Force One aircraft are slated for retirement around the time the B-21 is expected to come online.

Realistically, high-end military aviation projects are often best with unexpected delays, overruns, and technical hurdles, and given the Pentagon’s there’s little reason to expect that the most advanced bomber in history will be ready in time for current 747s’ decommissioning, or that it can be converted into a flying Oval Office by then.

But just as a thought experiment: what if the presidential B-21 could be built in time? Would the plane really be such a terrible idea?

Yes. Yes it would be.

Most glaringly, the presidential B-21 would mean entrusting the life and safety of the top echelon of the US government to a heavily modified version of a hazardously cutting-edge aircraft. The 747 or 737 are a logical means of presidential conveyance in large part because they’ve each been in widespread service for nearly 50 years—long enough for pilots, engineers, and international regulators to smooth out nearly every conceivable systemic safety issue (we hope!). The fuselage of a commercial airliner is you could possibly be in these crazy times. You’re in greater danger in your shower than you are on a Tuesday afternoon Islip-to-Logan flight in a 737 that’s potentially older than you are.

Let’s contrast this astonishing record of safety to that of the closest cousin of the B-21—the iconic B-2 stealth bomber. The B-2’s operational record is far from spotless, and the plane’s sheer awesomeness often obscures just how much of a disappointment it’s been. The B-2 has flown during US campaigns Kosovo, Iraq, and Afghanistan. But cost overruns, delays, technical challenges, , and then the subsequent non-existence of the Soviet Union meant that initial plans to build over 130 of planes were .

Just 21 of the aircraft were ever built, at $2 billion a pop. The B-2’s advantages over the existing B-52 Stratofortress—a bomber introduced in the early 50s—simply didn’t justify the cost of building more than a couple dozen of them.

The B-52 also had a dependability that the B-2 couldn’t match, almost by the stealth bomber’s very nature. The B-2 is the ingenious solution to an difficult engineering problem, namely, that of how delivering a nuclear weapon several thousand miles away without the aircraft being detectable on radar. The physics of keeping a stealth-capable nuclear-equipped plane aloft for 6,000-12,000 miles at a time are incredibly daunting, which explains why it took several decades for the B-2 to finally come online. The B-2 was created for a narrow range of conceivable scenarios (most of them Soviet Union and nuke-related) and built to operate at the absolute upper limits of what was then believed to be technologically possible in military aviation.

Such bleeding-edge-type aircraft are flyable, but they’re not always safe. Of the 21 B-2s ever built, a whole 4.7% of them have crashed, and another 4.7% were severely damaged when one of its jet engines . The morbidly fascinated aviation geeks among you can actually watch the B-2’s single hull-loss incident, an abortive takeoff at Andersen Air Force Base in Guam in 2008 (the two pilots ejected and survived):

The crash was apparently the result of a malfunction of the aircraft’s wing sensors during takeoff. The sensors falsely told the plane’s flight computer that the bomber was actually entering into a nose-dive, resulting in the computer angling the plane’s nose in order to pitch the aicraft dramatically upward. The pilots realized the error couldn’t be manually corrected in time to save the aircaft, and made the . The incident illustrates why these pilots got to fly the B-2 in the first place – they had enough of an instinctive understanding of one of the world’s most complex aircraft, of which only 20 currently exist, to immediately recognize mortal peril and then extricate themselves from it.

Civilian passengers don’t belong aboard such a plane. Presidents certainly don’t belong on them. The B-2 is serviceable enough as a stealth bomber, but the expertise needed to fly and maintain the thing limits its range of uses. Civilian aircraft are meant to be durable and flyable under most conditions. There’s a reason civilian planes are often adapted to military uses: The became a workhorse military transport aircraft, and the Boeing 737 became the submarine-hunting . There are comparatively fewer examples of military airframes being adapted for civilian passenger use. There’s the , the durable World War II-era military transport aircraft renowned for their ability to lift a large cargo haul off of a relatively short runway. Surplus C-47s were converted to civilian use, and there a still a few of them in service. But sticklers will note that the Skytrain was itself just a military version of the still-beloved civilian . Passenger aircraft don’t look anything like an F-35 or a B-2, and they probably never will.

There’s one other huge problem with our hypothetical presidential B-21. I guess that given infinite time, expertise, and resources, one could theoretically a build a B-21-type plane that can carry scores of passengers and a secure executive suite, and also all of the necessary communications gear and emergency medical facilities that a modern presidential aircraft requires. But the wingspan and fuel load of an aircraft that could lift that much weight while retaining its operating range while remaining undetectable to radar would be fearsome to contemplate. A plane that big would probably need specially-built runways to accommodate its sheer weight and size. It would be a flying absurdity—or, more likely, a grounded one.

Also, it wouldn’t be a B-21 anymore.

The Presidential B-21 is the latest in a string of attention-grabbing aviation fantasies, up there with , or Elon Musk’s Mars mission (kidding!). The nonexistent and never-to-exist plane is a fun thought exercise that actually yields an unexpectedly valuable, if somewhat depressing conclusion: The human race has had the fundamentals of passenger aviation more or less figured out for the last half-century, to the point where suggestions for improvement or re-thinking seem downright quixotic.

is a New York-based writer and editor who has reported from throughout Africa and the Middle East.