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This G650 has been flying around for over an hour now. Is this somebody with a mechanical problem who is burning fuel before returning to their airport of origin?

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What you observed is probably a Gulfstream production test flight, either an initial or a snag clearance flight, or possibly a Customer Acceptance from Savannah Air Center, which is a completion center across the ramp from Gulfstream. It could be possibly an experimental test flight if Gulfstream runs experimental flying from Savannah (I think they have a test operation in Wichita), but production flights are far more common.

The manufacturer will have designated test areas by agreement with the appropriate ATC units, with specific boundaries, and they will flight plan into the test area for production test flights (aircraft coming off the line) where a Functional Test Procedure, usually taking several hours to complete, is performed. The ATC clearance will be to maneuver anywhere within the test borders, with a block altitude clearance they are free to operate within, until they need to go higher or lower for different tests and request a new block.

The pilot flying will be steering this way and that pretty much randomly, within the test area borders, while the other pilot performs systems tests, and the two of them will do a number of flight tests where they operate the airplane to, but not beyond, it's certification margins (things like stalls, engine shutdown/relights, yaw damper function, anti-ice tests, those sorts of things).

The airplane will return with or without snags, and the plane will get snags cleared, and go back out for another flight to check the snagged items. On a corporate aircraft it'll then go on to a Completion Center (usually a separate company selected by the buyer for high dollar corporate a/c) for the interior.

Once the completion Center is done the interior, the customer or a customer's agent is taken on a Customer Acceptance flight before accepting the a/c. They will go through the cabin to make sure everything is perfect in the cabin, both fit and system wise, getting it fully cold-soaked to make sure valves don't freeze, and subject to pressurization changes that can make interior panel joints open up (and I mean perfect - the slightest flaws in panel fits will be snagged).

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    $\begingroup$ I'm a little surprised that they do this kind of thing directly over ca. 100,000 people. Why not pick a quieter spot? $\endgroup$ – Strawberry Apr 16 at 9:00
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    $\begingroup$ What's an a/c in this context? Aircraft? $\endgroup$ – Mast Apr 16 at 10:17
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    $\begingroup$ Production flight test is not considered really "high risk" the way Experimental flight test is, so test areas don't need to be remote. The airplanes don't yet have a C of A issued and are under a flight permit, but are not being operated outside of certification limits. You can expect that there will be several areas designated. Which one is used on a given day will be based on traffic requirements. At my company a flight would file for one of 4 test areas and ATC would issue a clearance for that one, or one of the others if they needed to run a lot of traffic through the filed one. $\endgroup$ – John K Apr 16 at 12:53
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    $\begingroup$ @Mast yes a/c is a common abbreviation. $\endgroup$ – John K Apr 16 at 12:54
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    $\begingroup$ @Strawberry - Short of going out to sea, there aren't too many areas that large around Savannah or in fact on the eastern seaboard that aren't over populated areas. And if you did need to make an emergency landing for any reason, you'd want to be close enough to an airport (or better yet several airports) to be able to do that, which rules out testing over the ocean. $\endgroup$ – Darrel Hoffman Apr 16 at 15:50
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The fact that it's near Savannah and tracking within a confined airspace, I'm fairly certain this is a flight test being carried out by Gulfstream.

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    $\begingroup$ @MichaelHall I don't mean vertical loops. It's just tracking within a confined a confined airspace. $\endgroup$ – JZYL Apr 15 at 20:37
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    $\begingroup$ @JZYL, The word loop means a vertical loop... (horizontal loops are called "turns") I like your short, simple and to the point answer, but it perpetuates incorrect terminology unless you edit it. $\endgroup$ – Michael Hall Apr 15 at 21:04
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    $\begingroup$ @MichaelHall Thanks for pointing it out $\endgroup$ – JZYL Apr 15 at 21:10
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    $\begingroup$ @MichaelHall Just to clarify, the word loop in reference to aircraft maneuvering is vertical. In general the word loop can definitely be horizontal. $\endgroup$ – JMac Apr 16 at 14:57
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    $\begingroup$ @JMac, yes, your shoelace loop can be horizontal. But this is an aviation website and the question was about an airplane maneuvering, I really didn't think further clarity was needed... $\endgroup$ – Michael Hall Apr 16 at 15:40
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I would second what John K said, it’s most likely a GAC factory flight test or demonstration flight. Also with the airplane identified as GLF6 and, most likely going be the call sign “Gulf Test six” would pretty much confirm that suspicion. You will also see similar flights down to Brunswick Golden Isles airport (KBQK), as Gulfstream does a lot of flight test work down there as well.

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  • $\begingroup$ Indeed, is it slightly strange that test area is overa big population? $\endgroup$ – Fattie Apr 16 at 12:07
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    $\begingroup$ @Fattie, the sort of flight test they'd be doing here isn't dangerous. The Gulfstream is an established aircraft model, so it's well-known how it handles and most of the ways that it can fail. If they were doing something that carried a non-trivial risk of crashing, they'd be doing the test flight from an airport further west, with nothing but cows and wheat fields to hit. $\endgroup$ – Mark Apr 16 at 20:03
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    $\begingroup$ I guess it's more of a "test drive!" than what we think of from action movies as a test flight! ... heh $\endgroup$ – Fattie Apr 17 at 10:46
  • $\begingroup$ @Fattie -- yeah, production test flying has far more in common with post-maintenance functional check flights than it does with experimental or even certification test flying $\endgroup$ – UnrecognizedFallingObject Apr 18 at 0:00

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