Active Sky XP: the weather engine is fine, the simulator under it is not

HiFi's own product page for Active Sky XP still carries a sentence that has been wrong for nearly seven years. Under "Limitations", it reads: "We expect our visual cloud rendering replacement technology to debut in Q4 2019, subject to change based on many factors." It is August 2026. The technology never debuted. The page has not been rewritten. simMarket reprints the same paragraph, word for word, on the listing it is selling today.

Before anything else, be certain which box you are looking at, because HiFi has made this genuinely hard. There are three Active Sky products in circulation and the names barely differ. Active Sky FS is the MSFS 2020/2024 product. Active Sky Cloud Art is a cloud texture pack for FSX and P3D. This one — ASXP — is the weather engine for X-Plane 11, and only X-Plane 11. There is also a fourth, Active Sky XP 12, which is a different product with a different price tag and its own separate purchase.

That last distinction is the entire buying question. X-Plane 12 entered early access in September 2022 and went final on 17 December 2022, and its native weather engine was the single biggest thing Laminar rebuilt. ASXP does not run on it. HiFi's own FAQ answers this without hedging: "Can I still use ASXP12 with X-Plane 11? No. ASXP12 is for X-Plane 12, and ASXP is for X-Plane 11." HiFi did offer ASXP12 free to existing ASXP owners — but as a "free upgrade, for a limited time through May 19, 2023". That window closed three years and three months ago. Buy ASXP today and you own an X-Plane 11 licence, full stop.

Here is what makes this awkward rather than simple: the record on ASXP as an X-Plane 11 add-on is good. Ten of the twelve simMarket reviewers gave it five stars. It is simMarket's number eight all-time bestseller. Even the people who trashed the X-Plane 12 version in 2024 went out of their way to say the X-Plane 11 one had been essential. Nothing about the software broke. What moved was the platform under it, and HiFi's own attention, and neither the store pages nor the price followed.

We read 26 sources for this review: the developer's product pages, news posts and support forum, four reseller listings, threads on X-Plane.Org, AVSIM and the Aerosoft and HiFi forums, written reviews and video coverage. Reddit is blocked in the environment this review was researched in, so the usual sentiment-at-a-glance check is missing; for a product whose loudest constituency is an ageing X-Plane 11 userbase, that absence matters less than usual, because the forum threads are where those people actually are.

What you are actually buying

A weather engine that runs as a separate Windows application alongside X-Plane 11, downloads real-world observation and forecast data from HiFi's DataNet servers, and writes it into the sim through X-Plane 11's weather API. It is not a cloud renderer. The clouds you see are X-Plane's own, optionally re-textured by a bundled wizard.

Product	Active Sky XP (ASXP)
Developer	HiFi Technologies, Inc.
Simulator	X-Plane 11.26 or later, 64-bit Windows only
X-Plane 12	Not supported. Separate product (ASXP 12)
Released	12 December 2018
Latest build	B8546, "Update 052623", posted officially 1 June 2023
Download	252 MB
Requires	Online HiFi account, one active login at a time

HiFi runs no store of its own. Active Sky sells exclusively through four authorised resellers, and the prices do not line up:

Store	Active Sky XP (XP11)	Active Sky XP 12
simMarket	€29.99	€29.99
Aerosoft	€29.99 (excl. VAT)	—
Just Flight	US$32.99	US$31.99
Flight1	US$34.99	US$31.99

Read that bottom half twice. At both American stores that list both products, the X-Plane 11-only engine costs more than the current X-Plane 12 one. At Flight1 it is three dollars dearer for a superseded simulator.

Do not try to declare a winner across currencies from that table. simMarket's terms say displayed prices "include the respectively applicable value added tax", which for an unresolved session means zero — Aerosoft's €29.99 is stated explicitly as ex-VAT, so the two are not the same number in the same sense. And because HiFi publishes no price of its own anywhere on hifisimtech.com, there is no developer figure to check the resellers against. That is not an omission on our part; there simply isn't one.

If you fly X-Plane 12, the sensible buy is not this product. It is ASXP12, which is newer, cheaper at two of the four stores, and still being updated — HiFi shipped ASXP12 build B9573 in 2026.

What the community consistently praises

The data. Every source that likes ASXP likes it for the same reason, and they have been saying it in the same words since 2019. Rabso, on X-Plane.Org in February 2019, planned flights in PFPX using ASXP's own weather input and found plan-versus-sim "very close" compared with anything else available. Artur's simMarket review in October 2019 called it the most accurate weather engine for X-Plane 11. TinkerNZ, arguing in 2024 against someone who had written the product off, said that for "low and slow bush flying I value the accuracy" and the wind variation between small altitude changes. Winds aloft, in particular, come up again and again — this is the feature nobody disputes.

The application itself is the second thing. ASXP is not just an injector; it is a planning and monitoring tool with a map showing SIGMETs and precipitation, route weather briefings, historical weather, and voice ATIS and Flightwatch delivery on 122.00, 122.02 and 122.03. Threshold's reviewer singled out the integrated flight planning as the thing that separates ASXP from every other X-Plane weather tool. melb00m made the same point on X-Plane.Org in February 2019 against FSGRW. A browser-based companion lets you drive it from a tablet over the network.

The air feels alive. This is the recurring phrase, and it comes mostly from general aviation pilots. Paraffin, on AVSIM in March 2019, put it plainly: the air felt more alive than in any other weather add-on he had used, and ASXP was the only injector he knew with a slider for how much icing you get. Yosri A. on X-Plane.Org in March 2021 said his main complaint about default X-Plane weather was how "buttery" it felt, and ASXP fixed exactly that.

It is cheap on frames. Because ASXP uses X-Plane's own cloud rendering rather than replacing it, the engine costs almost nothing — the application runs outside the sim. Where users did report a frame hit, it traced to the optional high-resolution cloud textures or to stacking extra layers, and the bundled high-performance texture set exists for that. Threshold's reviewer saw no simulator pausing on weather updates at all.

Finally: HiFi answer their tickets. Across the XP 11.53 crash thread in 2021 and scattered activation problems, the pattern is the same — public forum posts go quiet, support tickets get resolved. That is a real and unglamorous virtue.

What keeps coming up as a problem

Weather redraws and abrupt transitions. Status: still open, and structural. This is the oldest complaint on the record and the one that never went away. rchappy88 in September 2019 described clouds changing "in an instant" and was eighty per cent of the way to giving up on X-Plane over it. Threshold's reviewer called out the same behaviour — ASXP clears the weather for a couple of seconds and then generates the new area. HiFi's own FAQ concedes it: the smooth theme reload feature from the FSX and P3D products "is not provided", and the fix was tied to the cloud visuals replacement that never shipped. JohnC079 gave it as his reason for quitting ASXP as recently as 2024.

The ring. Status: still open, and not really HiFi's fault. Philipp's two-star simMarket review of 5 February 2019 described bad weather rendered as "a 'ring' around the aircraft with a good weather on the horizon". Alexander, replying the next day on the same listing, agreed the ring exists and pointed out that it is an X-Plane 11 API limitation that no weather add-on had solved, and that X-Plane 11 offers only three cloud layers — put fog in one and something else has to go. Both men are right, which is why this argument ran for years. Paraffin's summary on AVSIM is the fairest: ASXP is a very good real weather injector, which is half of what xEnviro does; the cloud depiction half is missing.

Turbulence that throws airliners around. Status: mitigated, never fixed. The_Avionics_Guy opened a thread in 2019 titled, in as many words, why the turbulence is so jerky. matrosov, in January 2021, shelved ASXP because weather refreshes sent the Zibo 737 into barrel rolls and FlightFactor aircraft "nuts". prosco in 2022 described the Zibo walking "like a dead leaf" under variable wind. The answer offered in every thread is the same: turn the turbulence and wind-shear sliders down. That works, and it is also an admission — the defaults are wrong for tube liners, and they were still wrong three years after release.

Crashes tied to X-Plane point releases. Status: fixed, case by case. Between 20 March and 3 May 2021, three separate users on HiFi's own forum reported X-Plane 11.53 crashing on launch with Active Sky running. HiFi staff asked for tickets and logs; one user fixed it by reinstalling the asx-connect plugin, another by correcting the install destination, and the original reporter confirmed resolution on 2 May 2021. Handled — but it took six weeks in public.

Online dependency. Status: by design, and a long-term risk. ASXP will not run without an account login to HiFi's servers, one session at a time. When Windows 11 updates KB5066835 and KB5065789 broke network HTTP functionality in October 2025, HiFi confirmed the crash affected all Active Sky products; the resolution was a subsequent Microsoft patch on 18 October 2025, not anything HiFi could ship. A product whose licence check lives on someone else's server has a shelf life you do not control.

No upgrade path for loyal customers, then a free one nobody was told about loudly enough. MartynC on X-Plane.Org in March 2019 had bought Active Sky Next and AS16 with Cloud Art and complained that long-standing HiFi customers moving to X-Plane got no discounted upgrade. Four years later HiFi did the opposite and gave ASXP12 away free to ASXP owners — for eight weeks, ending 19 May 2023. If you missed that announcement you now pay twice.

Performance and stability

ASXP is one of the lightest weather solutions on the platform, and that is a direct consequence of its biggest limitation: it does not draw anything. The engine sits outside X-Plane and hands it data. Users on X-Plane.Org in March 2021 agreed the plugin itself costs nothing measurable and that any frame loss came from cloud layers or the optional high-resolution textures. Compare xEnviro, which replaces the atmosphere wholesale and which one user in the same period ran at 30–40 fps against 50–60 without it.

Stability is a mixed but not alarming picture. The 11.53 crash cluster of spring 2021 is the only clustered crash report we found, and it resolved. The October 2025 Windows 11 breakage hit every Active Sky product on every platform and was Microsoft's to fix. What we did not find is any 2024, 2025 or 2026 report of ASXP failing on X-Plane 11 — but then, we found almost no 2024, 2025 or 2026 discussion of ASXP at all. HiFi's support forum now runs dedicated sections for ASFS, ASXP12 and ASP6; there is no ASXP section, and the general X-Plane forum's most recent post is dated 16 January 2025, a staff reply about changing an account email address.

The honest read on stability is therefore: it works, on a sim that stopped changing, so there is nothing left to break it.

Who should buy it

You are still on X-Plane 11 and intend to stay there. Buy it. This is the whole case for the product and it is a strong one — nothing else gives X-Plane 11 this quality of wind and observation data, the planning tools have no rival on the platform, and the sim is frozen so the compatibility risk is nil. Budget an evening to pull the turbulence sliders back.

You fly airliners on X-Plane 11 and plan in PFPX or SimBrief. Buy it. The winds-aloft accuracy is the single most-praised thing in seven years of threads, and it is exactly what makes your flight plan match your fuel burn.

You fly low and slow on X-Plane 11. Buy it, and turn the icing slider to taste. The GA pilots are the most consistently enthusiastic constituency in the entire record.

You fly X-Plane 12. Do not buy this. It will not run. Buy Active Sky XP 12 instead, which at Flight1 and Just Flight costs less than this does — and read the X-Plane.Org argument from mid-2024 before you buy that either, because since X-Plane 12.1 several experienced users have concluded the native engine is now good enough.

You want better-looking clouds. Do not buy it. ASXP has never rendered a cloud and the plan to make it do so was published with a Q4 2019 date and abandoned. Look at xEnviro, which reached v1.34 and does replace the atmosphere.

You are on a Mac or Linux. You cannot buy it. Windows 64-bit only, and the "we hope to bring additional OS/platform support in the future" line on HiFi's page is now eight years old.

Where it stands today

Active Sky XP is a good product that has been left standing on a platform its own developer has moved off. The last build, B8546, landed on 26 May 2023 and was a mandatory .NET 4.7 security update — housekeeping, not development. Every HiFi news post since concerns ASFS, ASXP12 or ASP6. The company is plainly healthy and plainly busy; it is simply busy elsewhere, and that is a reasonable commercial decision that a buyer in 2026 should nonetheless be told about before they pay.

The pricing is the part that is hard to defend. A €29.99 or $34.99 asking price for an X-Plane 11-only engine, three and a half years after the last build and three and a half years after X-Plane 12 went final, is a legacy price presented as a current one. That Flight1 charges more for it than for the X-Plane 12 version is the clearest possible illustration. Nothing about the listings is untrue — simMarket and Flight1 both carry an explicit "for X-Plane 12, see the ASXP12 product" line, which is more than HiFi's own page manages — but the price has not moved to reflect what is being sold.

And it will still sell, because it deserved its reputation. Ten of twelve simMarket reviewers gave it five stars, which the site rounds to a headline "5" though the actual mean of that 10/0/0/2/0 spread is 4.5. It is the eighth best-selling product in simMarket's entire all-time catalogue. When someone dismissed Active Sky on X-Plane.Org in June 2024, the reply came from a user who agreed about the X-Plane 12 version and still called ASXP an essential add-on for X-Plane 11. That is the correct epitaph. If you are on X-Plane 11, this is the best weather your sim will ever have. If you are not, it is not for you, and the store page will not stop you buying it anyway.