Show HN: Dovepass – can I legally fly a drone along this exact path in SF? (dovepass.com)
I build route planning for delivery drivers and wanted to check what it would look like if the vehicle flies. Drone navigation is different from land-based vehicle navigation. In addition to road and traffic data, it requires data on buildings, building height, wind speed and direction, and total load, including the payload a drone might carry. It is also governed by a set of rules; depending on the area, federal, state, or county rules may apply.
The decision point becomes whether, at each point on the route the drone can fly based upon whether regulations permit, the wind direction favours it and whether it flying over a road or people? Depending on when the drone flies, the same path valid two hours ago may no longer be valid.
For example a trip from 24th & Valencia ( Mission) to 19th Ave & Irving (Inner Sunset) and back is 5.1 km each way. A DJI mini 4 Pro would take 19 min on 7 mph winds from the west and use 92% of its usable battery and give a Go signal with warning. But at 11mph wind from the same direction would become No-Go because it would use 111% of its usable battery. Or whenever there is a Giants game at Oracle Park, this route is unusable because it is 2.5miles from the stadium. FAA bars all drones within 3 nautical miles from a stadium from 1 hour before the game to one hour after it ends.
I chose San Francisco as the first city to build this because there is enough data about the buildings (92% coverage), wind data is easily available at the drone flying height, and the city has a mix of slopes, water bodies, buildings and airport-related airspace restrictions all in one city. The city also has local rules regarding drone flights in parks - both operated by the city as well as by Golden Gate National recreational areas ( National Park Service).
I used kimi to build it and claude acted a sa judge. To understand more about the challenges faced during the build and the tradeoffs made please read - https://dovepass.com/how-it-was-built/"
10 comments
[ 4.5 ms ] story [ 45.1 ms ] threadI would like to integrate this w/ the agentic state, my email is on profile, please LMK if we can chat.
- TY Arion
> Your landing point is 7 ft (2 m) from a 164 ft (50 m)-tall building — taller than drones may fly, so we keep at least 80 ft (25 m) from it.
The numbers are from just clicking a random spot, but I'm kind of confused about how you're interpreting the regulations. In the US, the maximum allowable altitude is 400 feet AGL per § 107.51(b), albeit with a structure exemption for Part 107 pilots. Within a 400 foot radius around a structure, you can fly 400 feet above said structure's maximum height. That drops down to 400 feet AGL the moment you go beyond that radius, however.
Setting aside both the math error with the building height and the structure exemption, what's the basis for the exclusion zone that's being referenced? Granted, you absolutely want horizontal separation near buildings to account for winds that can easily slam a drone into a window, but the error message could imply that your 80 foot clearance is a nonexistent regulatory rule. I'm guessing that's just a conservative safety margin to make flight planning easier, but you should explicitly identify it as such so as to avoid ambiguity or the implication that it's a prescriptive FAA regulation. There's a reason why clarity and precision are so critical in pretty much any aviation document.
Anyhow, it's an interesting concept, one that I could see it being useful in planning but I'd double check some of the altitude logic. I'd also add references to error messages that point to the relevant regulations that trigger the warnings.
0. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-F...
1. https://pilotinstitute.com/drone-altitute/
I'm still not quite sure what calculation would have a marked location like that as a "no-go," and re-reading the error messages doesn't really clarify the logic. When it says "too tall to clear safely from there" I'm reading that as the building is too tall and thus you can't fly above it, but that's clearly wrong on two levels. Likewise, the building height + 400 feet was still well below the floors of the relevant Class B and Class C airspace shelves around SFO and OAK. Best guess is that the 80 foot exclusion zone around a building the program applies is probably to blame.
There are some other problems I noticed, but I'll send those to the OP via the feedback form on the site.
Planned TFRs like the fleet week are handled like this. Short notice TFRs are a weak spot if one lands after the last job. For commercial applications, the schedule would need checks at shorter intervals.
Stadiums are different. There is a standing FAA rule ( mentioned in the post). So each time a route crosses Oracle Park, a check is made to see if a game is present on that particular day and its starting time. Since we do not know when the match will end, we have made the assumption of 3.5 hours from the first pitch/start.