How a CT-4 Airtrainer Test Flight Turned Into a Spin Problem
- Peter Dickens
- Mar 6
- 4 min read
Updated: Mar 18
Back in the early 1970's, the Royal Australian Air Force was preparing to replace its ageing basic training aircraft, the Winjeel. The replacement would be the CT-4 Airtrainer, built in New Zealand, a light modern aircraft intended to train the next generation of military pilots.
Fifty aircraft were ordered.
A fairly serious investment.
Which made one small detail somewhat ... awkward.
The aircraft had not yet been properly evaluated by a test pilot before the purchase decision was made.
I may have pointed that out.
The Department of Air in Canberra (now known as the Department of Defence) agreed with the criticism and decided the sensible thing to do was send someone across the Tasman to investigate.
That someone turned out to be me.
A Trip to New Zealand
So off I went to Hamilton, New Zealand, courtesy of Qantas, where I met the team responsible for designing and building the aircraft.
The people involved were impressive, designers, engineers, and the company's own test pilot, all deeply invested in making the Airtrainer a success.
My job was simple in theory.
Fly the aircraft.
Evaluate its handling.
And make sure the RAAF hadn't just purchased fifty aeroplanes that might surprise trainee pilots in unpleasant ways.
The early flights went very well.
The aircraft handled beautifully.
It had gentle stall characteristics, predictable controls, and behaved exactly as a training aircraft should.
Everything seemed perfectly in order.
Which is precisely when I started thinking about the 'rumour.'
The Rumour About the CT-4 Airtrainer Spin
Somewhere along the way I had heard an interesting comment.
Apparently the CT-4 would not spin.
Instead, it would enter something called a spiral dive.
Now, that might sound like a minor technical distinction, but for a training aircraft it's actually quite important.
Student pilots are taught how to recognise and recover from spins.
If an aircraft behaves differently, or worse, unpredictably, that could become a serious issue.
But in my experience, almost any aircraft can be persuaded to spin if you try hard enough.
And, being a test pilot, trying hard enough is generally part of the job description.
Time to Find Out
Late one afternoon, just before dusk, I climbed to about 5,000 feet.
Not particularly high, but high enough to conduct the experiment.
I slowed the aircraft toward the stall.
Then I began applying rudder.
More rudder.
A little more rudder.
The aircraft slipped sideways.
The stall warning appeared.
At that moment I made a decisive set of control inputs, rudder, stick, and aileron, the sort of manoeuvre designed to encourage the aircraft into a spin.
And suddenly the aircraft began to rotate.
Well ... that answered one question.
The CT-4 could spin after all.
Unfortunately, after about one turn, the nose of the aircraft lifted toward the horizon and the controls didn't quite behave the way I expected.
In fact, the effort required to apply opposite rudder, normally the key to stopping a spin, was ... surprisingly light.
That was the moment a small voice in my head spoke up.
'Peter, it might be time to stop this experiment before things get interesting.'
The Good News and the Bad News
Eventually, with a fair amount of control input and concentration, I managed to recover the aircraft.
The landing afterwards was perfectly routine.
My knees, however, took a few minutes to catch up.
Back on the ground I called Canberra and spoke with the project manager.
I told him I had good news and bad news.
Naturally, with the project already attracting attention, he asked for the good news first.
"The aircraft will spin," I said.
There was a short pause.
"And the bad news?"
"It's not terribly keen on recovering."
Solving the Problem
That conversation led to the next phase of the project.
I was sent back to New Zealand to work with the manufacturer to solve the problem.
Flight testing spinning aircraft is part science, part engineering, and part art.
Together with the aircraft's designer, we developed a plan to gradually modify the aircraft's vertical stabilising surfaces, starting with the dorsal fin and increasing its size step by step.
Each change required another series of flights.
Another set of spins.
And occasionally the reassuring presence of an anti-spin parachute, just in case.
The advantage of working directly with the manufacturer was that changes could be made quickly. Within days we could modify the aircraft, test it again, and gather new data.
Progress was rapid.
Over seventeen sorties, and less than twenty hours of flying the team gradually refined the design.
Eventually the aircraft behaved exactly as a training aircraft should.
It would spin.
And, most importantly, it would recover.
The Final Demonstration
At the end of the program, I decided to demonstrate the aircraft's newly perfected spin characteristics.
Over the airfield at Hamilton, with the manufacturer's employees watching from below, I entered a spin and allowed it to continue.
One turn.
Five turns.
Ten turns.
Eventually it reached twenty turns before I initiated the recovery.
The aircraft responded perfectly.
Recovery occurred smoothly at around 500 feet above the airfield, which probably impressed the spectators slightly more than it impressed the air traffic controller.
The team was delighted.
And the CT-4 Airtrainer went on to become one of the most successful basic training aircraft in Australian aviation history, helping train thousands of pilots over the following decades.
A Trainer That Taught Generations to Fly
Despite early nicknames such as the "Plastic Parrot", the Airtrainer eventually earned deep respect among pilots.
It proved safe, reliable, and forgiving, exactly what a training aircraft should be.
In fact, its safety record is remarkable.
Thousands of pilots learned to fly in it.
Many went on to long and distinguished flying careers.
And all of them unknowingly benefited from those early test flight, the spins, the experiments, and the small adjustments that made the aircraft safer for everyone who flew it.
Want the full story?
This story is just one of the many stories from a lifetime of flying aircraft in situations that were occasionally challenging ... occasionally unusual ... and sometimes downright surprising.
If you enjoy aviation stories that mix technical insight, humour, and the occasional moment of tension, you'll find plenty more in Life on a Wing and a Prayer.
Inside the book are real flying stories from decades of aviation, from fighter jets to jungle airstrips and everything in between.
