A New Zealand agricultural pilot, who struck wires, has an urgent message for other pilots about the creeping effects of fatigue.
The pilot was spraying and seeding gullies when the underslung seeding bucket hit wires the pilot forgot about.
“I got to the job and did my usual recce around the block. There was a set of wires running over three of the gullies. I flew along the wires to mark the location and direction on my GPS.
“I started spraying, and I’d completed all the sensitive1 boundaries against the neighbours’ property first. Then I was going to work on the gullies that had wires.
“The wind had picked up, so I decided to stop spraying and move on to the seeding. After about a half-hour break, we took the spray gear off and attached the seeding bucket. I decided to do the seeding the same way as the spraying, so I started on the area against the neighbours’ boundary first. I shifted to the gullies, starting a run over the wires I’d marked on my GPS.
“I was looking forward and outside of the aircraft, and I didn't see the wires. I’d forgotten about them.
“My seeding bucket caught the wires, pulling on the aircraft. Of course, I instantly remembered them then, and I released the bucket from the aircraft.
“The aircraft flew normally, and I did a quick circle to have a look. The bucket had caught and broken two wires. After I released it, it landed in a field of wheat.”
The pilot has a piece of advice that’s relevant to all general aviation pilots:
“Slow down the job to take in all the risks and hazards – and make the safest decisions to complete the job.”
The CAA investigation found that the cause of the occurrence was high workload. The operator was reduced to one helicopter, and there was a limited weather window for the pilot to complete the job.
The operator’s Chief Executive endorsed the CAA’s findings, and has told all their pilots they’re free to stop work if they’re feeling tired, pressured or concerned.
The Chief Executive also reinforced to their pilots the message to slow down, to make sure all risks and hazards are identified and mitigated.
The pilot realises – with hindsight – that after two busy days of early starts, he could have managed his fatigue more actively. He acknowledges he became mentally overloaded during the job.
He says he should have sprayed and seeded the gullies while his mind was fresh and alert. Doing the runs parallel to the wires, rather than flying over them, was another option.
The incident caused no physical injuries, and there was no damage to the aircraft or to property.
What’s the impact of fatigue?
Fatigue reduces your ability to work safely and effectively. It’s mainly caused by inadequate sleep and/or excessive workload over time. It increases the likelihood of errors, which can lead to more workplace incidents and injuries.
Combined with too many mental demands, fatigue can lead to the sorts of memory lapses this pilot experienced when he hit the wires.
Cognitive overload
Part of the problem is that pilots don’t make decisions in a vacuum. The average person makes between 33,000 and 35,000 decisions a day.2
CAA Aviation Safety Advisor, Pete Gordon, says, “Before they even get into the aircraft, pilots make decisions that are affected by many things, including their fatigue levels and the time of day or night. The more tired they are, and the more decisions they face, the less time they spend on those decisions.
“They’re making decisions just to get them out of the way, or postponing decisions to reduce the mental workload.”
Pete recalls the time he got back to the hangar after a long day of top dressing, shut down the aircraft and pulled out his diary to calculate his flying hours.
Try as he might, he couldn’t add up. The numbers swam in front of his eyes, and his brain couldn’t compute them. Starting to feel like a ‘dunce’, he put his diary away and headed home to bed.
Coming fresh to the task the following morning, Pete quickly calculated the numbers. He was shocked at how the arduous flying schedule the day before had affected his ability to complete a simple mental arithmetic task most eight-year-olds could do.
“I was lucky it was only my arithmetic I messed up that day,” he says.
The most vulnerable time
Fatigue creates predictable risks for pilots. One of the most vulnerable times, Pete says, is towards the end of the shift, especially on the last sector to an overnight stopover, or home.
“Decisions start to get clouded by wanting to get to the destination. That starts to override reasonable decision-making.”
He says it’s crucial to have planned for what to do if you need to divert or stay put. And involving others in your decision-making is important to reduce mental load.
This is particularly so if you’re part of a crew, he adds.
Solo pilots can also share the decision-making. Talk to home base or other pilots. FISCOM and air traffic control will be happy to help your decision-making with weather updates and other key information.
Pete recommends using a kneepad for easy access to information on frequencies, charts, checklists and the like.
Eating regularly and staying hydrated are vital, but often overlooked, ways of combatting fatigue. Keep a water bottle beside you and sip regularly.
Fatigue: what the law says
New Zealand’s Health and Safety at Work Act 2015 says employers have a legal duty to take ‘reasonably practicable steps’ to ensure the safety of employees at work.
Fatigue is an identifiable risk and examples of ‘reasonably practicable’ steps could include:
- employees take regular, quality rest breaks that take account of the intensity and duration of the work they are performing,
- lengthy working hours are monitored and effects managed
- critical tasks that require focus and alertness aren’t scheduled during times when most people are tired (for example, towards end of work shifts) or ‘low points’ (3-5am and 3-5pm)
- rosters are designed to allow good sleep opportunity and uninterrupted recovery time between workdays, ensuring there is a clear understanding of when a person is at work, or available for work, and when they are completely off duty.
Employers must have a fatigue policy that includes information about maximum shift length, average weekly hours, work-related travel, and procedures for managing fatigued workers and reporting fatigue risk.
Employees must also take reasonable care to keep themselves and others safe, including:
- turning up fit and well rested for work, having sought to get a good sleep and rest
- telling their manager or supervisor if a task is beyond their capabilities
- recognising the signs of fatigue
- reporting fatigue-related incidents.
Photo credit: iStock.com/simonbradfield
Footnotes
1 Sensitive areas in spraying activities include proximity to waterways, organic crops, public areas and housing.
2 A simpler way to make better decisions. Reill, A, Harvard Business Review, December 2023.