All the detail is in the Description section on Youtube. For those too lazy to go there:
Autonomous drone delivering a chocolate bar from Kowloon side to the south side of Hong Kong island in less than 14 minutes.
Quadcopter always in sight and control of multiple operators along the route. Anyone wanting to try this, read below.
Placing waypoints is easy, but ensuring long distance flights are as risk free and safe as possible requires a lot of time & planning and especially meticulous surveying of the route.
All kinds of unexpected surprises not visible on satellite imagery such as new construction, cranes and power lines can be in the flight path, so make sure you survey in person.
Google Earth/DTED elevation data can be inaccurate, especially along mountain ridges, and values do not include the height of obstacles (buildings, trees, ...) – make sure to include enough buffer, at least 80m over hilly terrain. Use a site such as www.emporis.com to check building heights, don't forget to include add local elevation in the calculation.
Measure the distance carefully and perform a test with the same distance, climbs, descents and any special autopilot actions as the actual planned flight to verify there are no bugs. Afterwards, check the battery voltage and capacity used to verify it has sufficient reserves for the planned flight (e.g. in case wind conditions change). If not, adjust plan and test again.
Check if nearby mountain peaks have high power transmitting stations. They knock out video and/or control, sometimes they even GPS. Plan accordingly and verify your failsafes.
There are moments when you can receive less than 5 satellites – these usually last less than 30 mins, but if this coincides with your flight and you're using a regular GPS (especially NAZA), keep a large distance from everything. Use a GNSS planning tool or a mobile app to check the # of sats for your planned location and time, and take into account any obstacles such as mountains/buildings that shield part of the sky.
Modern receivers such as the UBLOXX-M8N are much more reliable as they can receive GPS, GLONASS and/or BEIDOU simultaneously. Make sure the antenna is dual-band.
Helicopters and private planes often fly low – you and your spotter must have a clear view of the airspace. If you fly beyond your visual range, you need additional pilots stationed further along the flight path with their own transmitters that are bound to the vehicle. Verify the behaviour of your failsafe after takeoff.
Use windfinder.com or an aviation weather service to confirm tailwind and no strong gusts.
Also, make sure you know the applicable law and guidelines given by the local aviation authorities. They exist for a reason, and all real pilots will sleep better knowing that RC hobbyists are doing their best to comply.
Don't perform flights like this if you've changed any hardware or updated any software/firmware in the last five flights. Especially software is evolving fast, and new bugs are constantly found.
Although unlikely, Motors can fail, ESC's can burn out, a prop can fly off, sudden vibrations can confuse the IMU, a bird could attack the vehicle, ... Plan to avoid as much as possible any flight over buildings, roads and people.
Do your first five flights over an empty field. If something's wrong, this is when you'll notice. Know how to react when your vehicle suddenly flies in an unintended direction. Practice this so you can quickly react when this happens. Know how to switch to and fly in a mode without GPS (Attitude mode, stabilise mode, manual mode, ...)
Yes, all this takes a lot of time and dedication. Plan and fly thoroughly and carefully. An accidents will ruin this hobby for yourself and the community.