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How do you design a really quiet midsize aircraft cabin? Well, it helps to get acoustics advice from a company that manufactures nuclear submarines. Gulfstream was able to do just that when it designed the G150: its parent company, General Dynamics, builds subs for the U.S. Navy, including the super-stealthy Seawolf class. That’s just one of the reasons why the G150 has the quietest cabin in its category, according to Stan Dixon, Gulfstream vice president for mid-cabin programs. 

Even though it has been around since 2005, the G150 in many ways still flies under the radar when it comes to midsize business jets. Nevertheless, it boasts a long list of attributes, including more versatility than lots of competing aircraft. The model offers an ovoid fuselage that yields generous head and shoulder room; a nice galley with running water and a microwave; top-of-the-line interior fit, finish and features; a contemporary and PlaneView cockpit with large glass-panel displays and the ability to host the latest safety features. The G150 also has the capability to carry four passengers and their luggage 3,000 nautical miles unrefueled at a respectable cruising speed. (Anyone who has cruised cross-country in some older business jets knows what I’m talking about here—it’s not that the cars on the freeway below are really going faster; it just seems that way.) 

Another point in the G150’s favor is that you can give it a beating and it will keep coming back for more. According to Dixon, the model has the highest mission availability rate of any Gulfstream. Given that the company consistently rates number one in product support, that’s saying a lot. The highest-time G150 currently has flown 8,000 hours and several customers use it as a shuttle, taking off and landing 10 to 12 times a day. And a few fly these marathon hours without an in-house maintenance department. 

Part of this durability can be credited to the G150’s certification to the MSG-3 maintenance standard: key components are replaced based on condition rather than on a calendar/hourly basis. This is the same standard to which the airlines adhere. But you can’t really pull off MSG-3 unless the aircraft’s design and construction are robust and to get an insight into that you have to look at the G150’s lineage. 

It began in 1984 with the Astra jet, which was itself a derivative of the Westwind 1124. Westwinds may be the ugliest business jets ever made but they were built like bricks. Israel Aircraft Industries, which made this aircraft under contract, tweaked the design by adding a swept wing and reshaped fuselage frames to increase speed, cabin space and headroom. The nose was elongated to fit more avionics and turbofan TFE731 engines were added to make the aircraft quieter and more fuel-efficient. 

The Astra SP and SPX derivatives followed over the next decade. The SPX incorporated numerous improvements, including full-authority digital engine controls and avionics, more powerful engines and winglets. Collectively, these modifications gave the airplane a much faster cruise speed and a service ceiling of 45,000 feet. Gulfstream acquired the SPX program and rebranded it the G100 when it bought Galaxy Aerospace in 2001, but almost immediately realized the aircraft’s limitations and set about ­making improvements. 

The G100 was a speedster, but maximum payload with full was only 800 pounds and the 57-inch-wide cabin was more than a tad too confining for comfortable cross-country hauling. So in making the G150, Gulfstream filleted the G100’s fuselage and widened it by a foot. Cabin height increased two inches in the trenched center aisle. Baggage space increased to 80 cubic feet (55 of that external), the engines were uprated to produce 5 percent more thrust, the cockpit was outfitted with the more modern PlaneView system built around the Rockwell Collins ProLine 21 avionics and the flight controls were better harmonized.

As for the cabin, Gulfstream outfitted it with everything latest and greatest, including LED lighting (old hat now but a big deal back in ’05) and larger oval cabin windows. It also improved the galley and lav. Customers were given the choice of three basic layouts with cabin seating for six to eight (more seats mean a smaller galley), including the option of a two-place, side-facing divan. 

Still, with all this, only a little more than a hundred G150s have found their way to buyers. Yes, the midsize market is as soft as marshmallows, but there’s more to the story. As nice as the G150 is, there are some little niggling things about it that probably have kept it from selling better.

For starters, the aircraft achieves its impressive range by holding a little more than half of its 10,300-pound maximum fuel load in a fuselage tank aft the of the baggage hold. So, depending on your passenger load, you may not be able to take full external luggage—1,100 pounds—or full fuel and keep the airplane within its center-of-gravity envelope. 

Then there’s the baggage hold itself. Some crew have complained to me that the door is too small and too high off the ground—the sill is about five feet. 

The wings present more issues. The thin, aerodynamically efficient airfoil section gives the G150 great fuel economy and outstanding stability transiting turbulence, but it also means that the airplane needs slightly more runway than its competitors. The pneumatic deicing boots on the wing leading edges work fine and save engine power (as they do not require bleed air to be drained from the engines as deicing systems do on most jets), but they’re ugly. 

The quiet cabin, meanwhile, isn’t the only thing on the G150 that will remind you of a submarine: the main cabin entry door is short (4.33 feet) and skinny (2.1 feet). Due to its unique geometry, the G150 cabin is comfy, but it’s still about one-third smaller than you’ll find on a Hawker or a Citation Sovereign. 

Up front in the cockpit, those big windows give pilots excellent visibility, but they can also turn the front office into a greenhouse fast. This isn’t a problem on most airplanes, because they have dual-zone (cockpit/cabin) environmental controls. The G150 doesn’t, so somebody’s going to frost or fry. On a positive note, the airplane does feature Gulfstream’s “100 percent fresh air” system, which is good at keeping everyone healthy and ­ameliorating odors. 

These few dings aside, you won’t find anything on the market that delivers the consistent durability and economy of a G150, no matter whether your trip is 200 nautical miles or 3,000. A G150 enrolled in Gulfstream’s computerized maintenance program is virtually bulletproof. When it comes to versatility in a midsize cabin, the G150 is peerless.