Something's Not Right

Hour 996

It's not every day I find myself flying over Seattle with a dozen pairs of shoes in the back. It was a clear, quiet night, just after nine in the evening.  Night flying feels a little riskier any time I do it, but today was different.  We'd been in the air for just a few minutes when I had a sudden sense that something had just gone wrong with the plane. I couldn't tell you what, yet. The engine was still purring happily. But with 850 hours flying the same machine, I've gotten to know it, and somehow I knew that something wasn't right.

* * *

There's a fantastic military air museum in Tillamook, Oregon. They were producing a calendar filled with photos of ladies dressed as pin-up models posing against the museum's World War II-era aircraft. The curator had asked my wife L. to appear in the calendar so we were heading there for a photo shoot. She spent weeks excitedly putting together a dizzying array of outfits that I'd had the pleasure of previewing.

It had already been a long day. I'd driven between home and the airport three separate times trying to update the database on my brand-new GPS, fighting traffic each time. After work, we packed, but halfway to the airport, realized we'd forgotten something and turned back.  Though our original plan was to do the 75-minute hop in daylight, by the time finally reached the airport and packed all the suitcases and shoeboxes into the plane it was already after eight in the evening. Night was falling.

"I'm sorry -- I know we're already so late," I told her, "but I don't have my night currency."  It's pretty hard to maintain the legal requirement of three night landings in the past three months during Seattle summers; civil twilight is nearly 10pm at the solstice.  "I have to do three takeoffs and landings without you."

I started the plane up and did three respectable stop-and-go landings. I noticed something odd: during takeoff, with all my lights on, the ammeter showed the battery was discharging while the landing gear was retracting.  The alternator apparently wasn't generating enough power to keep up with the heavy electrical load. This probably should have been a clue that something wasn't right. Instead, I just tried working around the problem by turning off the taxi light during takeoff, and contemplated that it might finally be time to upgrade to low-power LED lights.

Returning to the ramp just before nine, I picked up L. and started the plane back up. We launched off of Renton into the clear night air and turned the plane south, contacting Seattle Approach to pick up our flight plan down to Oregon. The air traffic controller asked me to climb to 3,000'. I was busily trying to enter the list of waypoints the controller had given me into our GPS when it happened: I got a sudden sense that something on the panel had changed. I stopped, my finger hovering over my new touchscreen, wondering what was giving me the feeling that something wasn't right.

I started checking the panel systematically. All the primary flight instruments still seemed fine. The red post-lights illuminating the instruments were all still operating. The alternator warning light was not on. The wingtip strobes and navigation lights still seemed to be on, and I could see our headlight reflecting back off the propeller. The gear was up and the pump was off. Finally, I noticed it: my engine temperature monitor, which conveniently also monitors the avionics bus voltage, was flashing: "BAT 11.6V".

Wait, that must mean...

I checked the ammeter which measures whether the battery was either charging or delivering power.  The needle was pegged against the left-hand pin -- full discharge.  The whole plane was running off the battery. Uh oh. Airplane batteries are pretty small to save weight, so we didn't have a lot of time.

It was curious that the alternator's warning light was dark; it's why I hadn't noticed the problem sooner. I de-energized the alternator, which should cause the light to glow -- in fact, doing so had made it glow just ten minutes earlier when I'd tested it during the pre-flight engine tests.  I switched the alternator field on and off several times, but nothing changed.  I started to check the circuit breakers, when--

"Cardinal 97H, I can't climb you just yet, maintain 3,000."

Oops.  The failure had happened just after we'd reached 3,000', and I'd spent so much time heads-down trying to figure out what had happened that I'd neglected re-trimming the plane as we'd picked up speed. We'd climbed 300' above our assigned altitude.

"Sorry, descending to 3,000, 97H... and ... standby."

I was about to tell the controller what had happened, but decided I should tell my wife first.

"I'm really sorry, but, we have to go back," I told her. "The alternator isn't working."

"What does that mean?"

"The plane is not generating electrical power like it should. We have to land right away, because otherwise once the battery runs out, everything will go dark."

"You mean the engine will stop?" she asked, though to her credit, her tone was more inquisitive than concerned.

"Oh, no, no, the engine is fine, we're safe," I said.  I really have to work on my aviation problem-describing skills.  "It's just that in 10 or 20 minutes, the radios and lights will go out.  I have backups for everything, but we have to land as a precaution."  I started to mentally catalog my backup systems: my yoke-mounted GPS had 4 hours of battery; my flashlights were all out already; my handheld radio was behind me in my flight bag.

"Approach, Cardinal 97H," I said over the radio.  "We have to cancel IFR and return to Renton."

"Roger, IFR cancellation received, resume own navigation ... do you require assistance?"  Controllers are always so helpful if they think there's a problem.

"Negative, our alternator seems to have failed, but we should be able to get back on battery."

I turned the plane around and switched off all the lights to save power. A moment later, I realized how dumb that was -- there were other aircraft in the area, and I had just turned us into 2,500 pounds of invisible airborne aluminum. I flipped some of the lights back on. The legal requirement for anticollision lights isn't actually a bad idea!

I looked up, and, much to my surprise realized that I was lost. Perhaps it was just the stress of the situation, or my fatigue after a long day, but it was dark and I didn't recognize anything. The carpet of lights had no familiar features.  My new GPS suddenly seemed so confusing, despite the 15 hours I'd spent using the simulator before it was installed.  A few miles later I finally saw the flashing white lights at the end of the runway and brought us in for an uneventful landing.

After the plane was shut down, I called Seattle Approach on the phone. Before landing, when I'd asked to switch from their radio frequency over to Renton's, they'd asked me to call them from the ground. They wanted to make sure I was safe. When things go wrong, it's great to know that pilots nearly always have someone looking out for them.

I can't say this was my best day of flying, but honestly, the worst part was having to get in the car again.  At least there was no traffic!

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