ZK-GTR, January 1999 - In-flight Incapacitation Leading to Loss of Control

Date: 04 January 1999
Time: approximately 1600 hrs
Location: Maramarua
Registration: ZK-GTR
Aircraft Type: Schempp-Hirth Ventus B/16.6
POB: 1
Fatalities: 1


While flying a cross-country task with two other gliders in company, the pilot of ZK-GTR advised his intention to land in the vicinity of Maramarua. Witnesses on the ground subsequently observed the aircraft pitch up and then spiral steeply towards the ground. No apparent attempt to recover resulted in the aircraft impacting terrain. The first ground party to locate the wreckage confirmed the pilot as deceased.

A Schempp-Hirth Ventus similar to ZK-GTR Location of ZK-GTR accident, 04 January 1999
image embedded from Wikipedia on 30 August 2010 map embedded from Google Maps on 30 August 2010

Flight History

The accident aircraft departed Drury at 1304 hours on a two-lap cross-country task. On the second lap of the task, in the vicinity of Maramarua and at an altitude of between 2000 and 2500 feet, the pilot of ZK-GTR contacted the gliders in company to advise his intention of landing near Maramarua. The call was acknowledged and the other gliders continued enroute. ZK-GTR was subsequently seen by ground-based observers to be flying in a westerly direction from which a 180 degree left hand turn was executed. After rolling out from the turn, the glider was seen to pitch up rapidly and then spiral down into the ground.


A large anticyclone was positioned over the area on the day of the accident, giving fair weather with light winds and good visibility. Conditions were conducive to thermalling with areas of cumulus and stratocumulus cloud, although in the afternoon the onset of a sea breeze destroyed most of the workable lift resulting in some of the task aircraft landing out1.

Medical Factors

The pilot of ZK-GTR had previously held a private pilots licence (PPL), but in 1986 following a heart attack and angiogram which confirmed the presence of coronary artery disease, he was deemed permanently medically unfit for issue of any flight crew licence. A prime reason for this restriction was the known history of pilots clutching controls tightly when suddenly incapacitated due to chest pain, often resulting in a rapid pitch up, stall and spin.

In 1987 the pilot of ZK-GTR applied for a gliding medical certificate with another doctor (not his regular GP) and declared in this document that he did not suffer from any form of heart disease.

Following the accident, the wife of the pilot killed confirmed that he was asymptomatic since the heart attack in 1986 and fellow Auckland Gliding Club members reported that he appeared healthy and in good spirits on the day. The exception to this was one club member who remembered thinking that the pilot of ZK-GTR looked unwell and off-colour prior to the flight.

Wreckage and Impact

The aircraft impacted terrain on a river bank in a steep nose-down attitude, while spinning left.

CAA Analysis and Conclusions

The New Zealand Civil Aviation Authority (CAA) report into the accident1 concluded that the pilot was experienced at cross-country flying and given the conditions on the day, should have had no trouble completing the task. Although in advising his intentions to land at Maramarua, the pilot was not noticed to have been stressed in any way, it is likely that mild symptoms associated with his history of cardiac problems were the primary reason for his decision. The probable cause of the accident was subsequent in-flight incapacitation, the result of which is consistent with similar historical occurrences and the witness’s description of a pitch-up and loss of control with no evident recovery attempt. This cause was confirmed by post mortem, although the cause of death was the result of multiple injuries sustained in the crash. The impact was determined as not survivable due to the rapid deceleration sustained. The report also concluded that the pilot was medically unfit for issue of a flight crew licence and that his declaration to obtain a gliding medical certificate had been false.

HFACS Analysis

A brief HFACS Analysis of this accident reveals causal factors which can be classified as either unsafe acts or preconditions for unsafe acts.

HFACS Category Causal Factor
Exceptional Violations The false declaration by the pilot that he was not suffering from any form of heart disease was a significant contributing factor to this accident and clearly a violation. This unsafe act, albeit more than a decade prior to the accident, allowed the pilot to fly an aircraft when legally unfit to do so.
Adverse Physiological States The pilot’s precondition of coronary artery disease ultimately lead to in-flight incapacitation from which a successful landing was not possible.
1. Hunt, M. G. (1999). CAA Aircraft Accident Report: Occurrence No 99/1. Retrieved from http://www.caa.govt.nz/Accidents_and_Incidents/Accident_Reports/ZK-GTR_Fatal_04Jan1999.pdf on 23 August 2010.

Want to know more?

CAA Accident Report 99/1: ZK-GTR
The published Civil Aviation Authority of New Zealand report into this accident.
AviationKnowledge - Human Factors Analysis and Classification Systems (HFACS)
Visit here to find out more about the Human Factors Analysis and Classification System.
AviationKnowledge - Fatal Gliding Accidents in New Zealand
Visit here to find out more about other fatal gliding accidents in New Zealand.

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