Powered-lift / eVTOL
Distributed-lift passenger and cargo aircraft transitioning vertically out of a vertiport.
TechnologyControl the transition boundary.
Control the transition boundary.
Not the entire sky.
Aircraft moving between an access node and shared structured airspace pass through a narrow, high-consequence region where movements converge. VHS places deterministic access control on that boundary — and nowhere else.
Governing doctrine
No valid reservation — no access.
Patent-pending architecture for exclusive, time-bounded transition-access control. Provisional patent application filed.
Physical architecture
Four distinct elements, in one direction of travel.
The Transition Volume and the structured corridor are separate resources. VHS governs entry into the volume above the access node. It does not own, route or control the corridor network beyond the merge.
- 01Vertiport / access node
The approved surface where a movement begins or ends.
- 02Transition Volume
A vertically oriented, digitally defined cylinder above the pad, reservable by one authorized aircraft for one bounded interval.
- 03Merge transition
The engineered lateral path from the top of the Transition Volume into the corridor.
- 04Structured corridor
The directional route the aircraft joins after access, continuing beyond the merge point.
A reservable resource
Space, time and authorization become one allocation.
The protected transition region is not a drawn geofence. It is a resource that only exists as a combination of where, when and who — and access is evaluated against all three before use.
One aircraft. One defined Transition Volume. One bounded reservation window.
- X / Y
- Where is the protected resource?
- Footprint anchored to the access node.
- Z
- How high does it extend?
- A defined ceiling where the merge begins.
- T
- When is it reserved?
- One bounded interval, with a start and an end.
- AUTH
- Who may use it?
- One identified, authorized operation.
Space plus time plus an authorized aircraft is one controlled access allocation. This is not a geofence drawn around an area — it is a reservable operational resource.
Decision vocabulary
Three outcomes. No third meaning.
Decision labels are fixed vocabulary. Colour reinforces the label; the label alone is always sufficient.
GRANT
Required conditions are satisfied. The operation is authorized into the reserved Transition Volume for its bounded window.
HOLD
The request is valid, but the resource is not available under present conditions. Not a refusal — not now. The aircraft waits outside the boundary.
DENY
The request cannot be authorized. Entry is refused, and the refusal is recorded with its reason.
Deterministic pipeline
How a request becomes a decision.
- 01REQUEST
A structured operation requests access to a defined Transition Volume for a defined window.
- 02VALIDATE
Identity, reservation, timing and the applicable versioned policy inputs are checked.
- 03EVALUATE
Applicable conflict and access conditions are evaluated against the current resource state.
- 04DECIDE
The deterministic authority returns exactly one outcome: GRANT, HOLD or DENY.
- 05RECORD
The decision, its inputs and the reason for the outcome are recorded as facts.
- 06REPLAY
The same recorded inputs and versioned authorities reproduce the same decision for inspection.
Interactive · controlled illustrative scenario
Follow a decision through the boundary.
Two aircraft. One Transition Volume. Step through the sequence to see how a request becomes a deterministic decision, how the protected resource changes state, and what evidence remains afterwards.
Aircraft A holds a valid reservation for a bounded interval.
A requested TV-01 for a defined window and the applicable conditions were satisfied at evaluation. The allocation binds one volume, one interval and one authorized operation.
Aircraft A — decision
GRANTAircraft B — decision
No decisionAuthorized into TV-01 for its reserved window.
No request submitted at this point in the sequence.
Resource state — TV-01
- AVAILABLE
- RESERVED
- ACTIVE
- RELEASED
Resource states are drawn with dashed outlines; decisions are drawn as solid, colour-coded chips. is never a fourth decision, and is never a resource state.
This is an explanatory visualization of an authored illustrative sequence. It is not a live system, it issues no operational decisions, and it does not claim certification, approval or field validation.
Fail-closed doctrine
No valid reservation — no access.
The architecture is built around explicit access authority rather than assumed permission. If the required conditions cannot be established, the protected transition is not treated as authorized. Unknown never becomes GRANT.
Determinism
Built to be checked, not just believed.
The same authoritative inputs, plus the same versioned rules and conditions, produce the same decision. Each decision is recorded with its inputs, ordering, applied policy version and reason, so the sequence can be reconstructed later. No probabilistic, generative or inferential model sits in the decision path.
Technical dossiers
Open the architecture, exhibit by exhibit.
The story above stands on its own. These six exhibits carry the second layer of technical depth — geometry, 4D allocation, contention, evidence, the pending architecture and where VHS sits in the wider aviation system.
Operating principles
Six properties a reviewer can test.
These are not features. They are the constraints the architecture holds itself to, stated so that a reviewer can check each one against the engine rather than take it on trust.
- Deterministic decision
- One request, one evaluated set of conditions, one outcome. The same authoritative inputs and the same versioned rules produce the same decision — a property that can be tested rather than trusted.
- Reservation and access
- A reservation is a claim on a specific Transition Volume for a specific bounded window. Access is only ever evaluated against a valid claim: no valid reservation, no access.
- Conflict before priority
- Physical conflict in the volume is resolved first. Priority is only considered once the physical picture is unambiguous, so priority can never override occupancy.
- Evidence
- Inputs, ordering, the applied policy version and the reason for the outcome are recorded as facts, not as narrative log lines.
- Deterministic replay
- Recorded facts can be reconstructed in order, so a reviewer sees the same sequence the engine saw when it decided.
- Fail-safe behavior
- Unknown never becomes GRANT. If the state of the volume, the reservation or the participant cannot be established, the system withholds access.
Aircraft neutrality
The decision depends on conditions, not on the airframe.
Powered-lift / eVTOL aircraft, rotorcraft and commercial UAS are evaluated against the same volume, the same reservation model and the same conditions. Class-specific performance is an input, never an exception. Certification, flight characteristics and regulatory requirements differ by class; the transition-access coordination mechanism is what they share.
Rotorcraft
Existing civil, utility and emergency-services helicopters using the same access node.
Commercial UAS
Uncrewed inspection, logistics and survey platforms operating in the same transition volume.
What exists today
A working deterministic decision core, running controlled scenarios.
The architecture above is implemented in software you can watch decide. What follows is the honest boundary around it.
Verified current capability
- Working deterministic decision core
- Structured scenario processing
- GRANT / HOLD / DENY outcomes
- Evidence recording
- Deterministic replay
- Controlled scenario demonstration and visualization
Status and boundaries
VHS is prototype-stage. It is not certified, not FAA-approved, not operationally authorized, not deployed in live aviation operations and not controlling real aircraft. Geometry, altitudes, spacing and related parameters shown anywhere on this page are illustrative reference configurations, configurable per site and approved operating context. Provisional patent application filed — patent pending.
What this page deliberately leaves open
The questions a technical reviewer should ask next.
Each of these is answered in the Q&A diligence layer, where the edge cases, lifecycle detail and integration questions belong.
- What exactly causes a HOLD?
- What happens during emergency operations?
- Is the cylindrical geometry fixed?
- How does deterministic replay work?
- How does VHS fit with ATC and UTM?
- What does deployment require?
Deeper technical material sits in the resources layer; security-sensitive interfaces and implementation detail are reserved for direct technical review.
See the rules become a decision.
The architecture on this page is implemented in a working decision core. The VHS Engine runs the scenarios, issues the outcomes and records the evidence described above.