Pre-flight check

Summary¶

The pre-flight check is the structured process run before every flight: inspect the aircraft, verify the electronics, confirm the site and the pilot are ready, and only then arm. It exists because memory is unreliable under pre-flight pressure and an airborne failure is almost always worse than a delayed takeoff. The process is built around explicit go/no-go gates — a small set of conditions that must be true to fly — and is executed against the printable preflight-checklist. The maiden flight extends the same process into a first data-collection event rather than a celebration.

Concept¶

Why a check, not experience¶

Experienced pilots have accidents from skipped steps more often than beginners do from unfamiliarity. The pre-flight check exists because memory is unreliable under pre-flight pressure, because a missed step is invisible until something goes wrong, and because the consequences of airborne failures are almost always worse than the consequences of a delayed takeoff. The check removes memory from the sequence: the pilot executes a fixed list rather than recalling one.

This is the same principle as the coupon test in manufacturing — a few minutes of ground verification prevents a failure that is far more expensive in the air. The check is a process; the preflight-checklist is the artefact that process runs against.

The maiden flight as a measurement event¶

The first flight of a new build is not a performance. It is a data-collection event. Blackbox records the gyro signal, RPM filter performance, and motor outputs; post-flight inspection checks T-lock engagement, motor mount O-ring condition, and screws. The maiden answers a single question — how does this specific build actually fly, and where are its weak points — and every deviation from expectation is information, not failure.

Reference¶

Go/no-go acceptance criteria¶

These are the hard gates. If any is not met, the aircraft does not fly until it is resolved. They are the subset of the full preflight-checklist that admits no discretion:

Gate	Condition to fly
GPS fix	≥ 8 satellites acquired before arming (home point records at arm)
Battery	Resting voltage ≥ 24.0 V (fresh 6S pack), no swelling or deformation
Failsafe	GPS Rescue confirmed active (requires the GPS gate above)
RC link	RSSI / link quality good; transmitter powered before the aircraft
Structure	All 4 T-locks seated with no play; no visible frame or prop damage
Airspace	Authorisation confirmed for the site and altitude; two landing zones
Pilot	Not fatigued, impaired, or distracted

Everything else on the checklist is a verification step; the seven gates above are the conditions that turn a no-go into a go.

The checklist itself¶

The complete, printable step-by-step sequence — site, structure, electronics, powered verification, and pilot readiness — is maintained as a separate artefact: preflight-checklist. Print it or keep it on the phone; this article explains the why and the gates, the checklist is what you tick.

Procedure¶

Maiden flight sequence (extended pre-flight)¶

Complete the full preflight-checklist.
Arm in an open area, minimum 20 m from all people and obstacles.
Hover at 1 m altitude for 30 seconds. Listen for unusual sounds. Confirm the aircraft holds position without significant drift.
Verify OSD battery voltage drops normally (0.2–0.4 V at hover).
Land. Immediately feel all four motor housings — should be warm, not hot.
Press each arm laterally — T-lock tabs should show no movement.
Check motor mount O-rings — visibly compressed, not cracked.
Reconnect to Betaflight Configurator. Download Blackbox.
Review the gyro spectrum in Blackbox Explorer — confirm the RPM filter is removing motor harmonics and the noise floor is below −40 dB in the 0–200 Hz range.
If all checks pass, the maiden is complete. Proceed to normal flights.

Rationale¶

Why transmitter on before aircraft¶

If the aircraft is powered before the transmitter is connected, it sees no RC signal and immediately enters failsafe. For a drone configured with GPS Rescue, this can trigger unexpected GPS Rescue activation on the ground before the pilot has any control. Transmitter first ensures the RC link is established before the flight controller initialises its control loop. This is why "transmitter before aircraft" is a gate, not a preference.

Why GPS fix is a hard gate for arming¶

GPS Rescue cannot function without a home point, and the home point is recorded only at arm time. Arming without a GPS fix silently disables GPS Rescue for the entire flight. If the RC link is then lost over urban terrain, there is no automatic return. This is not theoretical — it is a documented accident cause in FPV operations, and it is why the GPS gate is non-negotiable rather than advisory.