Pilot incapacitation involving Cessna 208, VH-NTQ, near Horn Island, Queensland, 12 July 2016

What happened

At 1446 Eastern Standard Time (EST) on 12 July 2016, a Westwing Aviation Cessna 208 aircraft, registered VH-NTQ (NTQ), departed Horn Island Airport, Queensland (Qld), for a scheduled passenger flight to Cairns, Qld, with a pilot and seven passengers on board.

As the aircraft climbed towards the planned cruising altitude of 9,000 ft, the pilot began to feel light-headed, dizzy and short of breath. The pilot levelled the aircraft at 9,000 ft and engaged the autopilot. They then attempted to identify a reason for the symptoms, selected air conditioning off, opened a fresh air vent and ate a snack. No reason for the symptoms could be identified. As the flight continued, the symptoms intensified, the pilot felt tingling in their hands and fingers, and large head movements caused severe nausea.

About 20 NM north of Lockhart River, the aircraft approached a significant over-water segment. The pilot assessed that the symptoms would not pass and elected to divert to Lockhart River (Figure 1).

The aircraft landed at Lockhart River without further incident, the pilot and passengers were not injured, and the aircraft was not damaged.

Figure 1: Overview of planned flight

Source: Google Earth, modified by ATSB

Pilot comments

The pilot of NTQ provided the following comments:

• They were well rested and fit to fly prior to commencing the day’s duties.
• Prior to departing Horn Island, they were well nourished and hydrated.
• While conditions were not perfect, they elected to conduct a visual approach as large head movements exacerbated their symptoms.
• They had no pre-existing conditions which may have contributed to the incident.
• After landing, the symptoms quickly subsided and have not recurred.

Operator comments

The operator of NTQ provided the following comments:

• An engineering inspection of NTQ identified no defects. The aircraft has returned to service with no abnormalities reported.
• The operator interviewed the passengers the following day. No passenger reported experiencing symptoms similar to the pilot.
• After landing, an inspection of passenger baggage and aircraft cargo identified no dangerous goods.

Medical examinations

The pilot underwent medical examinations after landing in Lockhart River and the following day in Cairns. No contributing irregularities were identified.

ATSB comment

While the pilot did not return to Horn Island at the onset of the symptoms, the pilot’s decision to divert to an en route airport as the symptoms intensified rather than continuing to the intended destination demonstrates appropriate cautiousness in the face of uncertainty about their own ability to continue the flight.

Safety message

The ATSB safety education publication Pilot incapacitation occurrences 2010–2014 (AR-2015-096) documents recent pilot incapacitation occurrences in high-capacity air transport, low-capacity air transport, and general aviation to help educate industry about the causes and risks associated with inflight pilot incapacitation.

The ATSB report Pilot incapacitation: Analysis of medical conditions affecting pilots involved in accidents and incidents examined medical conditions and incapacitation events between 1 January 1975 and 31 March 2006. This report concluded that the majority of pilot incapacitation events do not involve a chronic or pre-existing medical condition. They are largely unforeseeable events, often involving acute illnesses or injury. Many are not in themselves life-threatening, but are capable of impairing a pilot’s performance to the extent that safe operation of the aircraft may be adversely affected.

Aviation Short Investigations Bulletin - Issue 53