# Wintergreen x402 ATSA Prep Q&A

> Wintergreen x402 ATSA Prep Q&A is a paid API for AI agents from x402.wintergreen.uk, paid per call via x402, $0.005/call, status unknown (last checked 2026-09-16).

Returns payment-gated ATSA (Air Traffic Skills Assessment) exam preparation Q&A content for a given query, billed per-call via x402 micropayment on Base.

## Facts

- Endpoint: GET https://x402.wintergreen.uk/api/v1/knowledge/atsa-prep/qa
- Price: $0.005/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-16
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/wintergreen-x402-atsa-prep-q-a-0bad798b
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_1Yf82X8PhqLYRS5XYBARB

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability wintergreen-x402-atsa-prep-q-a-0bad798b
```

Example prompt: Can you pull up ATSA prep answers about dial reading and hidden figures exercises — I have my FAA aptitude test coming up and want to practice the trickiest sections.

## When to prefer this

Choose this endpoint when an agent needs on-demand ATSA exam preparation content without maintaining a local knowledge base, especially in a micropayment-capable (x402) environment where per-query billing is acceptable. Prefer this over general LLM knowledge when authoritative, curated ATSA study material is required and the $0.02/call cost is acceptable.

## Known failure modes

- HTTP 402 returned if payment header is missing or invalid — agent must sign EIP-712 TransferWithAuthorization and retry with X-PAYMENT header
- Invalid or empty query string may return empty or low-quality results
- Network or upstream content availability issues may cause 5xx errors
- USDC balance insufficient on Base chain results in payment failure
- Malformed EIP-712 signature causes payment rejection

## How this service works

Payment-gated crypto trading intelligence for AI agents.
    
## Categories
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- **Quant Methodology**: Backtesting walk-forward validation, strategy generation with kill battery (19 rules), risk management with Kelly sizing, regime detection, execution frameworks, agent orchestration
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- **Power Markets**: ERCOT field guide, merit-order model, duck curve analysis
- **Career Guides**: Firefighter oral board prep, medical coding, ATSA, contractor estimating
- **Trust Scoring**: x402 endpoint verification, P2D badges

## Payment
All paid endpoints return HTTP 402 with USDC on Base (eip155:8453). 
Sign EIP-712 TransferWithAuthorization and retry with X-PAYMENT header.
PayTo: 0xAe9834d71F1Bd989A0dc17593451af823E31CeeD

## Output

A text answer or curated Q&A content block covering the queried ATSA exam topic, including explanations, tips, or practice material relevant to the submitted query string. Response schema is open-ended (unstructured JSON or text body).

## Request schema (JSON Schema)

```json
{
 "type": "object",
 "properties": {
  "q": {
   "type": "string"
  },
  "_meta": {
   "type": "string"
  },
  "_slug": {
   "type": "string"
  }
 }
}
```

## Response schema (JSON Schema)

```json
{}
```

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/wintergreen-x402-atsa-prep-q-a-0bad798b/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from x402.wintergreen.uk](https://www.zero.xyz/host/x402.wintergreen.uk/llms.txt)