A helicopter pilot escaped injury after the helicopter crashed during take-off at Archerfield Airport, south of Brisbane in Queensland, Australia, The Courier-Mail reported, describing the escape as miraculous1. The Herald Sun ran pictures of the pilot's narrow escape2. Beyond that, the coverage available to us gives few details and no cause.

What has been reported

According to The Courier-Mail, the crash happened as the helicopter was taking off, and the pilot was not injured1. The first reports appeared on Wednesday 14 October, Australian time12. The helicopter's type and registration, its operator and the purpose of the flight have not been published in the coverage available to us, and neither has the exact date and time of the crash or whether anyone else was on board. No cause has been reported. We could not find a notification from the Australian Transport Safety Bureau (ATSB) about the occurrence at the time of writing.

Archerfield, about 11 kilometres from the Brisbane CBD, is the city's secondary airport and a major centre for general aviation in Queensland, serving corporate aircraft, rescue and security services, charter, flying training and maintenance providers3. The airport says it has the largest number of general aviation movements of all Queensland airports and the most aviation operators and flying schools in the state, and that it has accommodated the largest number of helicopter movements in Australia since 20183.

Why lift-off is a critical phase

None of what follows has been linked to the Archerfield crash. It is general guidance from the FAA on the ground hazards around lift-off. The FAA's Helicopter Flying Handbook describes dynamic rollover as a lateral rolling tendency of a helicopter that is in contact with the surface during take-offs or landings4. For it to occur, three factors must be present: a rolling moment, a pivot point other than the helicopter's normal centre of gravity, and thrust greater than weight4. Causes listed in the handbook include failing to remove a tie-down or skid-securing device, a skid or wheel contacting a fixed object while hovering sideward, gear stuck in ice, soft asphalt or mud, and improper landing or take-off technique4.

The handbook is blunt about how quickly it develops. If a slow take-off is attempted and the cyclic is not positioned and adjusted to account for translating tendency, the critical recovery angle may be exceeded in less than two seconds4. If the critical rollover angle is exceeded, the helicopter rolls on its side regardless of the cyclic corrections made4. Opposite cyclic alone cannot stop it: quickly reducing collective pitch is described as the most effective way to stop dynamic rollover from developing, and the handbook stresses that it can occur with any type of landing gear and all types of rotor disks4. In its chapter on basic manoeuvres, the FAA adds that dynamic rollover accidents usually occur over a level surface, and that a slow ascent allows the pilot to stop if responses indicate hung or entangled landing gear, centre of gravity problems or control issues5.

Ground resonance and the European data

A second ground hazard is ground resonance, a destructive vibration that the FAA says affects helicopters with articulating rotors, usually designs with three or more main rotor blades, at certain rotor speeds while the helicopter is on the ground4. It can cause a helicopter to self-destruct in a matter of seconds4. The handbook's guidance is to close the throttle immediately and fully lower the collective if rotor rpm is low, or to fly the helicopter off the ground if rpm is in the normal operating range, and it notes that skid-type landing gear is not as prone to ground resonance as wheel-type gear4.

Rollover has also featured in accident data. The European Helicopter Safety Team (EHEST), whose safety leaflets are published by EASA, reported that data from an analysis of European helicopter accidents between 2000 and 2005 confirm that a continuing significant number of accidents are due to pilot disorientation in degraded visual environments, vortex ring state, loss of tail rotor effectiveness, and static and dynamic rollover6. If you are considering a career on rotary wings, our guide to becoming a helicopter pilot explains the training route.

What is not yet known

In the coverage available to us, key facts about this accident are not stated: the type of helicopter, who operated it, what the flight was for, when exactly it happened and what went wrong. Any cause will only be known once investigators or the operator release findings, and until then this report will not speculate. We will update this article if the ATSB or the operator publishes details.

Frequently asked questions

Was the pilot hurt in the Archerfield helicopter crash?

No. The Courier-Mail reported that the pilot escaped injury1.

What is dynamic rollover?

According to the FAA, it is a lateral rolling tendency of a helicopter in contact with the surface; once the critical rollover angle is exceeded, the helicopter rolls on its side regardless of cyclic corrections4.