After a particularly bad day at work where everything seemed to have gone wrong, I was booked for the last dual night navigation exercise before my night VFR flight test.
The Cessna 172 we were flying was about 40 years old and was starting to show its age. For example, the tacho on this aircraft had been replaced with a pre-loved unit a week or so previously and again about 20 minutes before we did the pre-flight checks.
Sometime after take-off, Brisbane Centre finally cleared us for an off-track departure to avoid the usual barrage of RPT traffic that passes directly over Archerfield every night of the week.
After being passed to the controllers at Amberley, we were cleared to track to our intended destination – Goondiwindi – and climb to 6,500 feet. Approaching top of climb, the second-hand tacho suddenly indicated zero RPM. But we heard the engine still running at normal speed and airspeed and vertical speed (climb rate) were unchanged. Definitely an instrument failure rather than a major engine issue.
A few seconds later, the panel instruments started to dim. We adjusted them back up a couple of times.
Next there was a strong smell of burning electrical components in the cabin. We immediately switched off the panel lights and turned on the backup red lights.
For night VFR you must carry a portable light source for emergencies; we had several. There was also an iPad to assist with navigation if the GPS also decided to cease functioning.
We found that no circuit breakers had popped of their own accord. Therefore, we believed that whatever was causing the burning smell was not caused by a dead short. Maybe just a case of a small component somewhere having developed a high internal resistance? If there was smoke in the cabin, we could not see it.
Were some, all or none of these issues related? Was it just coincidence?
The second decision was to immediately call our new best friends at the other end of the radio. At night ATC are there to guide you safely around the other traffic that you share the skies with, even when flying ‘visual’. But when things are not going well, they are also your lifeline and best source of help.
After advising ATC of our issue and requesting a return to base, we turned for home, with approval to descend to 5,000 feet. We needed to balance maximum gliding distance with the possible need to get on the ground urgently if things got worse. Amberley ATC (which is military) kindly offered the use of their runways if needed.
The electrical smell persisted after the instrument lighting was turned off. But acrid electrical smells can often get stuck ‘up your nose’ and seem to be present long after they have really dissipated. We opened all the fresh air vents and the odour seemed to dissipate. We were reasonably sure, but still not entirely confident, that the instrument lighting was the source of the smell. But it may have been related to the tacho failure, or something else again.
As mentioned, the tacho had just been replaced by a LAME, for the second time in as many weeks. As the nest of aging electrical wiring behind the dash panel had been disturbed yet again, in our minds there was always the possibility that this procedure had caused some of the 40-year-old insulation on the wiring to fail and perhaps rub up against an oppositely charged part of the aircraft. The power feed to the tacho or other instrument lighting may have been disturbed just enough to cause a problem.
Operations seemed reasonably normal (aside from having difficulty seeing the panel instruments), so we committed to the return to Archerfield rather than diverting to Amberley. Brisbane Approach enacted the airport emergency plan at Archerfield for our arrival.Focused on everything but the landing, I managed to turn a close downwind into an early base turn at a speed faster than normal. Normally during the day, with no other distractions, I would easily be able to turn that mess into a quite acceptable (and safe) landing.
But tonight, I forgot the basics, like flaps, airspeed management and setting up for stable approach. I was also struggling to see the panel instruments as my sole light source was now the red light attached to my cap.
Its beam was, like me at that point, quite narrowly focused and not that bright.
Halfway down the runway, I decided this landing was not going to happen. Since nothing else had gone right today, I was not in the mood to push my luck, given the amount of runway behind me was growing quickly. I initiated a go-around, which normally would not raise an eyebrow. But tonight, to the assembled audience, it must have looked like there was a problem with the aircraft.
Unfortunately, I forgot to make a go-around call on the radio.
Later, during the debrief most of my decisions and communications during the flight were validated. These included the decision to discontinue the flight as problems started to mount up.
The only negative feedback was about my tardiness in broadcasting the go-around when emergency crews were watching with intense interest. A simple “ABC, going around” might have allayed the fears of the local emergency services, PolAir and Rescue 500 who were, in all probability, wondering whether to break out the champagne or the fire hoses.
At any time during the flight, I could have given up and handed over to the wealth of experience sitting beside me. But I try to treat every flight as a solo, never assuming anyone is going to save me from myself. That way when I do have an ‘emergency’ all on my lonesome, hopefully it won’t faze me too much.
Lessons learnt
- Don’t push your luck.
- Know your aircraft systems. Because we had a good understanding of the electrical system on this aircraft, we were reasonably confident our diagnosis was correct.
- Never be afraid to use ATC when you need help. It’s what they do best. They may live in towers, but they certainly are not ivory ones.
- Over-prepare, especially at night. There are a few simple things you can do like carrying extra portable light sources, navaids and portable radios.
- Prepare a strategy once the problem is identified. We had diversion strategies prepared based on aircraft conditions at given points in the return flight.
- Don’t assume you will continue to perform at 100% after things go wrong. But do try to make the most of unusual situations to improve your skills.
