C185, Wellington New Zealand, 1997
C185, Wellington New Zealand, 1997
On Monday 3 March 1997 at 1014 hours, privately owned and operated Cessna 185 encountered wake turbulence from previous departing aircraft, the pilot lost control of the aircraft at a height from which recovery was not possible and the aircraft descended to the ground.
On Monday 3 March 1997 at 1014 hours, privately owned and operated Cessna 185 became airborne after a take off roll which had begun at a mid-point runway position on runway 16 at Wellington International Aerodrome, behind a Boeing 727 which had just departed from the full length of the same runway and climbed directly ahead. The take off clearance given followed the pilot’s request to ATC for a waiver of the recommended wake turbulence separation which applied which ATC had granted as they were entitled to. When the Cessna encountered wake turbulence from the previous departing aircraft, the pilot lost control of the aircraft at a height from which recovery was not possible and the aircraft descended to the ground. Neither of the two occupants was injured but the aircraft was substantially damaged.
The New Zealand TAIC carried out the Accident Investigation. Their Final Report was published on 11 June 1997 and found that “the Cessna pilot should have allowed more time or distance between his aircraft and the departing Boeing 727. It was concluded that the pilot had then misjudged the likely region of wake turbulence in relation to his take-off path. It was also found that the error resulted not from a lack appropriate flight experience or a lack of awareness of wake turbulence and the adverse effects it can have on an aircraft encountering it but from a lapse in concentration. It was suggested in the Investigation Report that this lapse was probably partly due to the routine nature of the flight and partly because of the pilots preoccupation with some personal business problems which he had been dealing with prior to the accident flight and which remained unresolved.
The Report noted that “Standard separation criteria have been implemented world wide with good reason due to the viciousness and somewhat unpredictable nature of wing-tip vortices. Aerodrome controllers have an appropriate responsibility for only issuing advice and warnings about the potential for wake turbulence and for applying standard separations when they consider that wake turbulence is likely to exist. Pilots must accept the responsibility for avoiding wake turbulence, and use sound judgement when any warnings about its existence are given. Aerodrome controllers however should have clear guidelines to follow when granting a waiver of the separation standards. Some countries do not allow waivers to be granted in certain circumstances.” It also noted that “Some commercial operators allow their pilots to request (wake vortex separation) waivers. The potential therefore exists for a similar occurrence at a busy aerodrome with more disastrous results should an aircraft, for example, collide with a terminal building or strike a taxiing aircraft.”
Two Safety Recommendations were made to the National Aviation Authority (NAA) that they should:
- Ensure that waivers of the wake turbulence separation standards are restricted to Visual Meteorological Conditions (VMC) / day only, are required to be acknowledged by pilots using promulgated phraseology and are not permitted to be granted at all under certain specified circumstances.
- Publish another article on wing-tip vortices in their safety magazine so as to alert pilots and operators to wake turbulence concerns by highlighting the dangers of encountering such turbulence and explaining how it can be avoided.
- Mitigation of Wake Turbulence Hazard
- Wake Turbulence Hazard - A Pilot Check List
- Accident and Serious Incident Reports: WAKE
- The full New Zealand TAIC Report