My toddler loves planes, so I built her a radar

Original Article ↗ Hacker News Discussion ↗

An iOS developer built a minimalist, radar-style plane tracker as a toy for his airplane-obsessed toddler, sparking broader interest in hobbyist flight-tracking projects. Commenters explore how to receive ADS‑B signals with cheap SDR hardware, feed data to networks like FlightRadar24 and ADSBExchange, and integrate features such as augmented reality, audio alerts, and more realistic CRT-style visuals. The thread also touches on parenting and screen-time philosophy, with many valuing simple, shared tech projects that connect digital displays to real-world experiences like planespotting near airports.

DIY ADS-B and Data Feeds

  • Many suggest building a cheap ADS‑B receiver with an RTL‑SDR dongle plus antenna and using tools like dump1090/tar1090 or Rust decoders to get local aircraft data.
  • Users report impressive range (hundreds of km) even with simple indoor antennas, and much more from elevated locations or roof‑mounted setups.
  • Several networks (FlightRadar24, FlightAware, ADS‑B Exchange, airplanes.live, etc.) accept community feeds, often granting free “business”/premium access in return.
  • There is mention of controversy around ADS‑B Exchange and DNS issues around adsb.fi, with airplanes.live described as a community focal point.

API Choice, Reliability, and Alternatives

  • The app currently uses the free OpenSky API, which has no reliability guarantees; many report timeouts when HN traffic spikes.
  • Future versions are discussed: allowing user OpenSky credentials (basic auth) or even paid data sources; some argue an SDR‑based local feed would be more robust and higher‑rate.

Radar UI, Realism, and CRT Details

  • Several comments dive deep into how classic PPI radar CRTs worked: radial sweep, phosphor persistence, beam intensity mapping directly to return strength, and electromechanical vs electronic deflection.
  • Suggestions for more “realistic” behavior: blips painted only on sweep, fading based on phosphor‑like decay, extrapolating positions between sweeps, altitude‑based sizing using transponder size class, and color or icon encoding for aircraft type/altitude.
  • A bug is noted where the CRT scanline effect looks low‑res on some devices; cause is likely scaling of shader scanlines.

Use Cases, Extensions, and Toy vs Tool

  • Ideas include: local noise/low‑altitude alerts, party‑trick displays over your house, in‑cockpit offline maps, Alexa/Siri integrations (“what’s overhead?”), TTS announcements via MQTT, and AR overlays like FlightRadar24’s existing feature.
  • Some feel the simple, ad‑free, “toy first” design is a welcome contrast to commercial, data‑heavy apps.

Parenting, Kids, and Travel

  • Many share stories of plane‑obsessed kids, cockpit visits (typically on the ground), flight logbooks for children, and plane‑spotting trips near runways.
  • There’s debate on giving phones to toddlers: some are wary of screens-as-toys, others see this app as a co‑used tool to enrich real‑world observation.

Critiques and Limitations

  • A few readers are disappointed it’s not a true transmitting radar or hardware build and find the “radar” label slightly misleading.
  • Others compare it unfavorably to more feature‑rich apps (e.g., FR24 AR), but most still praise the craftsmanship and write‑up.