Tuesday, February 21, 2012
Murphy’s Laws Of Aviation
Why what you learned in flight school may be open to question
My most educational experience with an altimeter occurred on a trip to Germany in another Malibu, this one the first Lycoming-powered Mirage in mid-January of 1989. The weather had been bitter cold going into Bangor and Goose Bay, -25 and -40 degrees F, respectively. I had to resort to near-aerobatic maneuvers to get the gear down at both airports after the wheels basically froze up and refused to extend either by the normal, hydraulic method or the emergency system (another story entirely).
Out of Goose Bay, I was determined not to let that happen again. The jet stream was very low and screaming out of the west, providing a spectacular 90-knot push for the crossing to Iceland above 18,000 feet. I leveled at FL210, and soon was speeding toward my destination at just under five nm a minute, admiring the Northern Lights in the middle of the afternoon.
An hour from Reykjavik, I called Iceland control and requested a descent to 1,000 feet over the ocean. The plan was to cruise for an hour in warmer air to make certain the gear would operate as advertised. There were no other idiots out there in the dark of day/night, so Iceland approved my request. I dropped down to 1,000 feet above the ocean, engaged altitude hold and trundled on toward Reykjavik.
After a while, I began to notice a strange luminescence slightly below me, a dim, barely visible, blue-green glow in the solid dark of winter. It took only a few seconds to realize what it probably was.
I stabbed the autopilot disconnect and levered the yoke back as hard as I could, leveled at 2,000 feet indicated, then took a breath, amazed that I was still alive.
I'll never know if Iceland gave me an updated altimeter setting as I dropped through 18,000 feet and I missed it, or if they simply forgot. Either way, it was my fault for not resetting from the 29.92 setting used above 18,000 feet. As it happened, the region was in the middle of a typical Icelandic low, in this case 28.97, almost a full inch below normal. I had been cruising at perhaps 50 feet above the North Atlantic, maybe less, and the shimmering color was the natural illumination of the waves below.
The incident was totally my fault, but the bottom line was I became fanatical about altimeter settings. I update every chance I have. An incorrect altimeter setting is one error I may not be allowed to make again.
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