Technical terms, facility types, bodyflight disciplines, manufacturers, and economic metrics. Everything you need to read a tunnel spec sheet properly and choose without marketing fluff.
Closed-loop tunnel: air is pushed into the flight chamber, routed through side ducts, and recirculated. Modern high-end standard (iFLY SkyVenture, ISG, AERODIUM advanced). Pros: stable flow, quieter, weather-independent, climate-controlled. Cons: much higher capital cost.
Open-flow tunnel: draws air from ambient and expels it at the top (usually a single pass). Much cheaper to build, but flow is less uniform and more dependent on outside conditions. Typical of entry-level facilities and some outdoor installations (e.g. AERODIUM outdoor portable).
Tunnel tilted 30–45° designed specifically for wingsuit training. The angle simulates the horizontal/vertical ratio of real wingsuit flight. In Europe they are extremely rare: Stockholm (Sweden) and Fallschirmtreff Slovenia are the references. Not used for freefly or belly.
Open-sky or semi-open flight chamber, typically portable or seasonal. Often used for demos, shows, and tourist engagement (Dubai, coastal destinations). More unstable flight quality; not suitable for serious training or licensed jumpers.
The vertical cylindrical section where you fly. The two key metrics: diameter (measured at the floor, in meters) and usable height (from net to ceiling). Under 3.0m you're limited to solo belly; above 4.3m you can freefly as a duo; above 5m formations and advanced dynamic open up.
Informal industry classification. 1G = early recirculating 1990s (small diameters, high noise). 2G = 3–4m diameter, 2000s standard. 3G = 4.3m recirculating, current commercial standard (most iFLY facilities). 4G = 5m+ diameters with optimized flow and acoustic management (Aero Gravity Milan, Realfly Sion, some recent iFLY).
Airflow speed at the center of the chamber, measured in km/h or m/s. The declared value is the operational max; in practice many schools cap it at 90% to protect the facility. Determines whether you can fly head-down, competition dynamic, or real wingsuit.
How constant the flow speed is inside the chamber — between center and walls and across heights. Uniform flow allows clean moves and predictable dynamic; irregular flow creates "holes" and asymmetries that mess up the fly. Never a published number — you only feel it in flight and infer it from brand and generation.
The operator who regulates speed from the control panel during the session. A good operator is part of the training: anticipates the flyer's level, accompanies transitions, and protects from sudden changes. At top tunnels this is a dedicated professional, not a receptionist pushing a button.
Belly flying — horizontal position with belly toward the flow. First discipline you learn in tunnel and AFF. 4-way is the team competition: 4 athletes executing coded sequences in the shortest time. Typical operating speeds: 180–220 km/h.
Vertical positions. Head-up (sit): back parallel to flow, head up — 210–240 km/h. Head-down: head toward the floor, body straight — 260–290 km/h. Requires high-speed, high-ceiling tunnels. VFS (Vertical Formation Skydiving) competitions run 4-athlete teams.
The most spectacular and elegant modern tunnel discipline. Choreographed sequences of rotations, lines (linear counter-flow moves), rounds (chamber rotations), and moves (vertical acrobatics). Flown as pairs (D2W) or teams of 4 (D4W). Requires wide tunnel (≥4.3m), high speed, and a synchronized partner. Tunnel-only discipline — no sky counterpart.
Practiced exclusively in inclined tunnels (30–45°). Used to refine position, suit pressurization, transitions, and proximity maneuvers. Two European references: Stockholm and Fallschirmtreff Slovenia. Doesn't work in vertical tunnels — the suit doesn't pressurize correctly.
Umbrella term for tunnel flying as a standalone sport, independent of skydiving. Many indoor flyers have never made a jump. There are competitive circuits (IBA, FAI Indoor Skydiving Cup) and international rankings.
Indicative values in km/h referenced to declared flow at the center of the chamber. Flyer weight and body position shift the range by ±10–15%.
| Discipline / position | Range km/h | Requires tunnel |
|---|---|---|
| First-time, tandem tunnel | 150–180 | Any ≥2.7m |
| Solo belly / AFF prep | 180–200 | Any ≥3.0m |
| Belly 2-way / 4-way FS | 200–230 | ≥4.0m preferable |
| Freefly head-up (sit) | 210–240 | ≥4.3m 3G+ |
| Freefly head-down | 260–290 | ≥4.3m 3G+ |
| Dynamic D2W / D4W | 270–310 | ≥4.3m 3G/4G |
| Competition top freefly | 300–330 | 5m+ 4G |
| Indoor wingsuit | 170–250 | Dedicated inclined |
Industry reference unit. One tunnel hour is split into 1–2 minute sessions. European 2025 commercial pricing: €650–1,200 per hour for free sessions, depending on tunnel, day (weekday vs weekend), and booking lead time. Aero Gravity Milan and top iFLY sit at the high end of the range.
Block of hours bought together — typically 5h, 10h, or 20h. Discount vs hourly rate ranges from 10% to 25%. Must be used within 12–18 months. Standard purchase format for serious athletes and competition teams.
Coach hourly rate separate from tunnel time. Typically €60–180/hour in Europe, with top international coaches (world champions) above €250/hour. The coach inside the chamber doesn't pay tunnel time — they're part of the client session; outside work (debriefing, video) is usually bundled.
The fixed chamber camera records every session. Video debriefing with the coach is 50% of the training value: you review micro-corrections invisible to the naked eye. One hour of serious flying produces 40–60 min of debrief. If the coach doesn't do structured debriefing, they're not a coach — just a flyer flying with you.
One of the world's top manufacturers for latest-generation tunnels, particularly in the 4G segment with 4.3m+ diameters and optimized flow. Built Aero Gravity Milan (5.2m, 370 km/h — most powerful in Europe), Windobona Wien, and many others. HQ: Bottrop, Germany.
Latvian manufacturer specialized in both outdoor open-flow tunnels (shows, tourism, events) and recirculating units for commercial attractions. Historical supplier to theme parks, Expos, and Olympic ceremonies. HQ: Sigulda, Latvia.
SkyVenture is the Texas manufacturer that defined the 3G recirculating 4.3m standard. iFLY is the commercial brand running dozens of facilities across North America, UK, and the Middle East. The manufacturer-brand combo has built the world's densest tunnel network.
Czech manufacturer, primarily active in Central and Eastern Europe. Typical products: 3G 4.3m, decent acoustic management, more accessible capital cost than ISG. Supplier to facilities in Czechia, Poland, Slovakia.
Operator brand and also manufacturer/operator. Classic 4.3m diameters, aggressive commercial management. Main sites: Prague (Czechia), Tatralandia (Slovakia), Berlin (Germany). Good price-quality ratio for regular training.
The space has fragmented with local actors (single-site builders, small integrators). Quality varies and must be evaluated case by case. Rule of thumb: if the tunnel isn't built by one of the top 4 manufacturers, ask for technical data and flow footage before buying block time.