FSBuild 2: the navdata is current, the developer is not

On the evening of 31 January 2026, SimBrief went down. Not for one region — worldwide. An AVSIM moderator on the US east coast opened a thread asking whether it was just him, and within the hour people had checked in from Ontario, New York and New Zealand to confirm that the free flight planner the entire hobby now runs on had simply stopped answering.

What happened next in that thread is the reason this review exists. One poster wrote that he wished SimBrief "came as a downloadable desktop app with full offline support". Another agreed and said the fact that almost all flight planning now centres on one web service "doesn't make it any better". And a third, Luis Hernandez, said he was going to reinstall FSBuild on his main rig — he had used it for everything between FS9 and P3Dv5. The reply to him was the most telling line in the whole thread: "Wow, I remember FSBuild."

FSBuild 2 is a Windows flight planner that Ernie Alston has been selling through simMarket since 2006, and which by simMarket's own reckoning is still the eleventh best-selling product in the store's all-time list. It is a 21MB MFC application whose system requirements page still asks for a Pentium 700 and Windows 98. Its developer stopped shipping builds in August 2018 and stopped posting in his own support forum in November 2019. His website was returning a bandwidth-limit error the day this review was written.

And its navigation database is current to this AIRAC cycle. That is not a contradiction so much as the entire product: FSBuild's data is maintained by Navigraph, not by Ernie Alston, and has been since January 2011. A flight planner with stale navdata is a dead product. A flight planner with current navdata and a dead developer is something else, and worth being precise about.

We read 21 sources for this review, spanning 2004 to May 2026 — the simMarket listing and its twelve customer ratings, the developer's own site and support forum through the Internet Archive, AVSIM threads from 2010 to three months ago, the Navigraph support forum, VATSIM, X-Plane.Org, Sim-Outhouse, one written review and the single FSBuild video that exists on YouTube. Reddit is structurally unavailable to us, which for a product this old matters less than usual; there is no r/flightsim sentiment on FSBuild to miss.

What you are actually buying

One product, one price, one store.

Price	€20.00 at simMarket, checked 20 August 2026
Other storefronts	None. The developer's own site has never sold it — it links to simMarket
Latest build	2.4.0.35, announced by the developer 13 August 2018
Simulators	FS2004, FSX, FSX:SE, Prepar3D (users report through v5)
Not supported	MSFS 2020, MSFS 2024, X-Plane 11/12
Navigation data	Navigraph FMS Data Manager, every AIRAC cycle
Download size	21.15MB
Listed at simMarket since	26 October 2006

There is no price comparison to run here, which is unusual. Most developers sell direct and undercut the stores; Alston never did. The archived fsbuild.com front page carries a single purchase link and it points at simMarket. Note also that simMarket's terms say displayed prices "include the respectively applicable value added tax" — for a browser session that has not resolved to a tax jurisdiction, that is 0%, so €20.00 is the pre-VAT figure and an EU buyer will pay more at checkout. FSElite quoted the product at \$30.05 in November 2017, which is the same listing seen through a different currency and tax lens rather than a price cut since.

What is in the box is enormous, and that is not marketing. FSBuild ships a full high and low airway database with SIDs, STARs and transitions, the entire FAA preferred IFR and severe-weather route database, Canadian preferred routes, US Socal TEC routes, more than 10,000 stored flight plans, North Atlantic and Pacific track insertion, step-climb profiles, V-speed calculation by gross weight and temperature, and a printable navlog you can put your virtual airline's logo on. The export list runs to roughly thirty formats. Read it and you are reading a history of add-on aircraft: PSS 747/777 and A320, Level-D 767, 767PIC, Aerowinx PS1, Fly!II, Lago MD80, Flight1 ATR72, iFly 737 and 747, vasFMC, FSNavigator, Squawkbox, FSInn, IVAP, Radar Contact, FSAcars.

That list is simultaneously the best and worst thing about the product, and we will come back to it.

What the community consistently praises

The numbers are right. This is the finding that repeats most consistently across the longest span, and it is the one that matters most for a flight planner. "From SID/STARs and NAT tracks to fuel planning FSBUILD is always reliable and accurate," wrote a simMarket customer in September 2005. Twenty years later the same claim survives contact with modern cross-checks: on 15 February 2025 an AVSIM regular helping a newcomer debug a distance discrepancy in MSFS described FSBuild as "my testing flight planner" and quoted KILM–KMYR at 62nm — a figure the original poster then confirmed independently against both SkyVector and SimBrief. When a 2003-vintage planner and SimBrief agree to the nautical mile, the core engine is doing its job.

Fuel planning that reacts to the winds. A customer in January 2006 described buying ActiveSky specifically so FSBuild could import winds aloft, compute the wind component leg by leg and adjust fuel accordingly, then worked out the cost at about twenty pence per flight. The winds-aloft integration is genuinely leg-by-leg rather than a single cruise figure, and cruise fuel flow changes as modelled gross weight burns down.

It exports straight into the aeroplane. Several AVSIM posters make the same point in different words: you rarely load an FSBuild plan into the simulator at all. In an August 2012 thread about parking positions, a regular explained that the strength is that "it also creates plan in the format of most popular addons" — build the route once, and the .rte or .fpl lands in PMDG's or Level-D's or iFly's own folder, ready to be loaded as a company route in the FMC. For anyone flying tube-liners in FS9 or FSX, that is a workflow SimBrief only reproduces via downloader plug-ins that the older aircraft do not have.

Ernie Alston used to be exceptional. This deserves recording because it is why the product still has a reputation. He turns up in the AVSIM archives himself, politely pointing users at his own tips page for undocumented features. A 2005 customer wrote that "Ernie always provides excellent support". His forum shows him answering bug reports personally into 2019. The support failure documented below is a change in his behaviour, not a description of it.

It runs offline, on your machine, and it still starts. On 11 May 2026, an AVSIM poster discussing FS9 on modern Windows listed his running-alongside stack as PF3, FSBuild or SimBrief in Chrome, FS Real WX and the sim — on a Windows 11 laptop. A 2003-era MFC application launching on Windows 11 in 2026 is a small engineering compliment, and it is the direct answer to the January 2026 thread that opened this review.

What keeps coming up as a problem

The map is bad, and always has been. This complaint is older than most people's simulators and has never once been addressed. "Its main drawbacks are: a bad looking map, lacking info on adjacent navigational info, no ILS or bearing information," wrote a customer in November 2005. In October 2007 another was blunter: he wanted to look at the route he intended to fly, and the graphics on his Commodore 64 two decades earlier had been better. FSElite's Calum Martin made the same criticism in his November 2017 retrospective. Status: still open. The map in the product screenshots is a white rectangle with grey coastline vectors and a black line across it, and that is what you get.

It is hard to learn, and people say so on the way out. "Not user friendly. Not intuitive. Requires way too much configuration," wrote a simMarket customer in June 2005, adding that he would take FSNavigator over it any day. In May 2009 another, migrating from FSNavigator, said it took him a long time simply to work out how to export a flight plan and concluded that "for what it does, I find it overpriced and is overcomplicated where it doesn't need to be". Status: still open.

Auto-generated routes are not always sane. In a January 2011 Sim-Outhouse comparison against FlightSim Commander 9 and Abacus Co-Pilot Pro, a long-standing member who had used both said FSCommander "gave me a lot fewer very strange routings" on the transatlantic tests he uses as a benchmark. The thread's originator went on to try the FSCommander demo and reported reading elsewhere that it was superior. Status: unresolved in the public record — nobody re-ran the comparison, and the auto-router has not changed since.

MFC crashes at startup on Windows 10. The most recent customer rating on simMarket, dated 31 December 2017, is one star: "Unable to make it work in Windows 10. Always getting 'Fsbuild2 MFC Application' has stopped working." A support thread titled "Just purchased, MFC Application crash, FSBuild never starts" ran to twenty-one replies. Status: mitigated. Alston answered that thread on 1 February 2018 and shipped 2.4.0.34 the same day; 2.4.0.35 followed in August. The May 2026 AVSIM post above has the program running on Windows 11. If you buy it today you are buying the fixed build — but you are buying it from a store, not from a developer who will fix the next one.

The support channel is closed. In January 2019 a VATSIM member opened a thread titled simply "Ernie Alston - ISG and FSBuild", asking whether anyone knew if Ernie was still around, and noting that he did not appear to have accessed his own support forum since September 2018. The replies suggested trying LinkedIn. Being fair to him, that thread was premature: the archived forum index shows him answering an export bug on 7 May 2019 and a weather-integration question on 4 November 2019. But that November 2019 post is the last one from him in the record, the newest post from anyone in the entire FSBuild 2 support forum is dated 15 May 2020, and an AVSIM poster back in 2012 was already unable to register an account there. Status: still open, and terminal.

The website is a single point of failure. fsbuild.com was serving a 509 "Bandwidth Limit Exceeded" error throughout 20 August 2026, when we checked it repeatedly. That is not a permanent death — the Internet Archive holds a healthy capture as recently as 8 June 2026, so this is a shared-hosting outage rather than a domain lapse. But two things follow. The download and any residual support path go through that host. And so does a feature: the daily North Atlantic Track import pulls from pages hosted at fsbuild.com itself, as an AVSIM thread from 4 March 2010 documents in the configuration file syntax. While the site is down, so are your NAT tracks. Status: open and intermittent.

Nothing here reaches MSFS. simMarket's own Requirements field reads "FS9 FSX P3D". There is no MSFS 2020 or 2024 export, the .PLN it writes is the FSX schema rather than the one MSFS uses, and the January 2026 AVSIM poster planning to reinstall it said openly that he did not know whether it worked with MSFS's default ATC. Searching the official MSFS forums for FSBuild returns nothing. Status: open, and not going to change.

Performance and stability

There is almost nothing to report, which is the point. The installer is 21MB. On any machine built this decade FSBuild opens instantly, builds a transatlantic route with step climbs in under a second, and consumes a rounding error of memory. It runs beside the simulator rather than inside it, so it costs you no frames at all — the only practical friction is that alt-tabbing to it forces you into windowed mode, and the May 2026 AVSIM thread makes clear that is FS9's fullscreen behaviour on Windows 10 and 11, not FSBuild's fault.

The stability complaints in the record are all about installation and first launch — MFC runtime failures on Windows 10 — and they were addressed in the February 2018 build. We found no reports of the program crashing mid-session, corrupting a plan or producing a route it could not export. For an application of this vintage that is genuinely impressive, and it is the strongest argument that the underlying code was well written.

Who should buy it

The FS9, FSX or P3D pilot flying legacy tube-liners. Buy it. If your hangar contains a Level-D 767, a PSS Airbus, an iFly 737 or 747, a Coolsky MD-80 or a PMDG classic, FSBuild will build the route, compute the fuel against real winds, print a navlog and drop a company route straight into the aircraft's own folder with current Navigraph data behind it. Nothing free does that for those aeroplanes today. €20 is fair for that.

The cockpit builder and the deliberately offline simmer. Buy it, but check one thing first. Everything except the daily NAT and PACOT track feed is genuinely local — the airway, SID/STAR and navaid databases live on your disk and update through Navigraph's desktop client, so FSBuild will plan a flight with no internet connection at all. That is exactly what the 31 January 2026 thread was crying out for. The track feed, though, routes through fsbuild.com, and fsbuild.com is not reliable.

The MSFS 2020 or 2024 pilot. Do not buy it. There is no export path to your simulator, the plan format is wrong, and no one in twenty-one sources has demonstrated otherwise. SimBrief does everything you need, integrates with every modern airliner, and costs nothing.

The X-Plane 11 or 12 pilot. Do not buy it. The X-Plane export exists, but it targets an .FMS revision from the X-Plane 6 to 9 era, simMarket's own requirements line omits X-Plane entirely, and the last time anyone publicly asked whether it worked with X-Plane 10 — on the X-Plane.Org forums in 2013 — the community leader who replied could only say that the developer claimed support and left it there. Little Navmap is free and better.

Anyone who might need to ask a question. Do not buy it. The support forum's most recent post is from May 2020, the developer's last reply is from November 2019, the website was down the day this was written, and registration on the forum was already failing for some users in 2012. You are buying a program, not a relationship.

Where it stands today

FSBuild 2 has been superseded. That is the plain answer to the plain question, and pretending otherwise would be dishonest: SimBrief is free, is more accurate on modern airliner performance, generates a proper OFP, integrates with Navigraph Charts and with every current aircraft's own downloader, and is used by essentially everyone. Against that, a €20 planner last rebuilt in August 2018, whose interface has not changed since Windows XP and whose map looks like an atlas printed on a dot-matrix, is not a general recommendation. FSElite reached the same conclusion in November 2017 — "as useful as it is, it does not withstand the test of time" — and nothing in the eight years since has argued back.

But superseded is not the same as dead, and the specific reason matters. FSBuild's navigation data is current, this cycle, because Navigraph took the job over on 13 January 2011 and has never dropped it: a Navigraph staffer confirmed on 30 May 2025, in response to a user who assumed the opposite, that data is still provided for both FSBuild and FS-Navigator, and the FMS Data Manager still lists it. That single fact separates FSBuild from every other abandoned planner of its generation. Ernie Alston stopped maintaining the program; nobody stopped maintaining its brain. What you get for €20 is a frozen but functional 2018 executable sitting on top of a 2026 database.

The remaining audience is therefore narrow but real, and it is the one that spoke up on 31 January 2026 when the internet took SimBrief away for an evening: people flying twenty-year-old airliners in twenty-year-old simulators, people with a hardware cockpit and no interest in a browser tab, people who want the plan to exist on their own hard disk. For them the case is not nostalgia. It is that FSBuild does one thing SimBrief structurally cannot, and does it with data that is not out of date.

Everyone else should keep the €20 and open SimBrief. And if Alston ever does come back — the code plainly still works, and the export architecture was always the clever part — a rebuilt FSBuild with an MSFS target and a map drawn this century would find an audience faster than most people would guess.