Safety

This page comes before the assembly page on purpose. Most of what goes wrong with a small aircraft in a classroom happens while nobody thinks they are flying: during a firmware update, a wiring check, a photograph for the school newsletter.

The rule the rest of the page is made of

Propellers are four screws’ worth of work and take under a minute. A motor that spins up unexpectedly with them on is the single most common way anyone gets hurt by a machine this size, and it does not require a fault — a stray command, a reused program, a controller reconnecting after a dropout will all do it.

In the classroom

The ducts are protection, not permission. This airframe runs each rotor inside a carbon duct, which is a real safety feature and the reason it is plausible indoors at all. It protects the aircraft from a wall and a bystander from a glancing contact. It does not make a spinning propeller safe to touch, and it does nothing for eyes.

Bench work happens on a bench, and flying happens somewhere else. Keep them separate as places, not as intentions. A desk with a laptop, a USB lead and a drone on it is a bench; if the props are on, somebody has quietly turned it into a flight line.

One person at the controls. Whoever is running the program is the only person who touches the aircraft while it is powered.

Eye protection when propellers are on and power is connected. Including for the person holding the phone.

Before the first flight

The build itself gives you the checklist. Everything here is something the assembly either put in or left loose:

All eighty-two screws present, and none of them proud. A screw left over at the end of a build is a screw missing from the aircraft.
The eighteen join screws driven. Until those are in, the top plate is only resting on the spacers. Grip the two plates and try to twist them against each other — there should be nothing.
Nothing loose between the plates. Turn the aircraft over and listen. Every board in there is on standoffs, and every one of them was reachable at some point during the build.
The battery held by its mount, not by friction. It is the heaviest single item and it is on the outside.
The antenna in its holder, not tucked under a strap or against a plate.
Both camera lenses clear — the forward one and the downward one. The downward camera and the optical-flow sensor are how the aircraft understands where it is over the floor.
Props last. Fitted where you intend to fly, not where you built it.

Outdoors

Choose the space by what happens if the aircraft does not do what you asked. Not by whether the planned flight fits. The planned flight always fits.

Nobody downwind and nobody underneath. Spectators stand behind the pilot, never opposite.
Wind is the thing that surprises people who learned indoors. A small aircraft is a light one; a breeze that is barely noticeable at head height is a significant fraction of what these motors can do. If the aircraft is visibly working to hold position, the lesson is over.
Keep it where you can see which way it is facing, not merely where you can see it. Orientation is lost long before the aircraft is.
Ground the flight, not the program. Land and disarm before touching a laptop.

What the simulator did not teach you

This is the part worth reading twice, because a class that has flown well in the simulator arrives outdoors with real confidence and three specific gaps. What the simulator models sets these out in detail; here is what they mean on a real flight line:

The simulated aircraft always knows exactly where it is. There is no satellite positioning in the model at all, so nothing a student has done so far involves position drifting, degrading near buildings, or being lost.
There is no radio link in the simulator, so there is no losing it. Failsafe behaviour is not something any student has met. Know what this aircraft does when the link drops — before the flight, from whoever supplied it — because it will not simply stop.
Nothing in the simulator wears out. Props stay true, motors stay matched, the battery is new every time. Outdoors, a bent prop and a tired pack are ordinary.

When something goes wrong

Cut the power to the motors first and ask questions second. Whatever the program was doing, it stops mattering once the props do.

Never catch it. Not descending, not drifting, not “it’s only coming down slowly”. A damaged airframe costs a repair; a caught propeller costs a hand.

Wait for it to be still before approaching, and approach from where you can see the props are stopped, rather than from behind.

Then write down what happened, before the battery comes out. Which program, which step, what the aircraft did. This is the part everyone skips and the only part that prevents the second occurrence.

Rules that come from your country, not from us

Everything above is about the machine. Whether you may fly it, where, how high, how far, over whom, and whether the school needs to register anything are questions with legal answers, and those answers differ by country and change.

Before a class flies outdoors, get these four in writing from your national civil aviation authority — not from a forum, and not from this page:

Whether the aircraft needs registering, and whether the operator (usually the school, not the teacher) does.
What the pilot needs — a competency certificate, an online test, a minimum age, or nothing.
The limits that apply where you intend to fly: height, distance, and proximity to people, buildings, roads and airfields. Airfield and restricted-area boundaries are the ones people get wrong, and they are rarely visible from the ground.
What your insurance requires, which is often stricter than the law.

→ Assembly — the build, in the order that does not require taking anything apart again.