Never Again

GPS, terrain, and gear lights

December 1, 2007

Last Christmas, my family held a party in Salt Lake City. I decided to fly up from my home in southern California and return two days later. I was solo and the weather was forecast VFR both ways—the Piper Arrow, in which we had recently purchased a share, would be perfect.

The morning of my return flight, the sky was gray with visibility below one mile in snow. The weather report indicated multiple cloud layers with tops above Flight Level 200, the freezing level starting at the surface, and 40-knot headwinds at 12,000 feet. IFR was not an option.

Ceilings south of Point of the Mountain, a VFR waypoint between Provo and Salt Lake City, were reported at 1,000 to 2,000 feet with good visibility, then improving to 6,000 feet south of St. George, with clear skies in California. Weather reporting points are sparse and separated by mountain ranges south of Provo; developing an accurate weather picture is very difficult. There were no pilot reports from VFR flights. I waited.

Later in the day the visibility at Salt Lake City improved to three miles in haze and light snow with 1,000-foot ceilings. I decided to depart and follow Interstate 15 southbound staying below the clouds to avoid icing.

South of Point of the Mountain visibility improved but the ceilings were a bit lower than forecast. Following the interstate seemed a good option although 100 miles south of Salt Lake City, the road crossed Scipio Pass, a narrow spot where its surface would reach 7,000 feet with surrounding peaks of more than 10,000 and 9,000 feet. The low valley to the east was not an option as its south end was also surrounded by high terrain.

As I approached Scipio, the interstate ascended into the cloud base. The ceilings were forecast to be higher at Cedar City Regional Airport farther south, but how to get there? I considered backtracking. But the ridges to the north and west were also obscured. I decided to climb VFR above the layer covering Scipio Pass.

At 6,500 feet msl, 500 feet over the highway, I began a climbing 360-degree turn. At 7,500 feet I realized that I had entered a "sucker hole" with no opening at top and the bottom possibly moving over high terrain. Descending back down the hole did not seem a good idea.

I had not used flight following because there was no radar coverage low in the narrow valleys. My handheld GPS showed the interstate but did not depict terrain features. I finally contacted ATC and asked for a "pop-up" IFR clearance direct to Milford VOR and then Victor 21 southwest-bound at 12,000 feet. Center gave me the requested clearance and warned that I would not be in radar contact until reaching 9,000 feet. I had now entered the clouds with granite peaks closing in. I used the GPS to maintain my position over the highway away from the peaks. After a tense few minutes I reached an altitude above 10,400 feet. I started breathing easier and picked up a heading toward Milford.

Level at 12,000 feet, I evaluated the situation. Ground speed was down to 105 knots and the aircraft had picked up a trace of light rime ice. Then I felt turbulence and the airplane yawed and rocked as the ground speed dropped to 90 knots. I suspected I was encountering the forecast frontal boundary stretching across central Utah.

I checked the wings and sure enough they had picked up more ice. The Arrow had no heated pitot tube, but the airspeed indicator was still functioning, though it showed a lower speed than was normal. Then, the airspeed indicator stopped working: The outside air temperature was minus-10 degrees Celsius.

I was flying the aircraft at full throttle with the nose pitched up just to maintain altitude. I was concerned about additional ice accumulation. I told the controller of my situation and requested an approach to Milford Municipal Airport. He approved the request and provided vectors and descent instruction for the approach. During the descent, I encountered VFR conditions between two layers. Light to the south indicated conditions continued for some distance.

I told the controller that I was in VMC between layers and asked for a VFR-on-top altitude of 11,500 feet. The request was approved. I leveled off but found that even with full throttle I was barely able to maintain altitude, in danger of descending into the icy clouds below me.

My ground speed was 80 knots. As I adjusted trim and leaned the mixture further in hopes of gaining some performance improvement I saw three green lights on the panel. I checked the gear switch; it was up. I then realized that auto-extension of the gear had caused the yawing, rocking, and 15-knot drop in groundspeed. I pulled the gear override handle and the three green lights winked off as the gear retracted. Now able to maintain altitude, my groundspeed increased to 100 knots.

As darkness set in and the meager sunlight to the south vanished I had to strain to ensure that I could visually keep myself separate from the icy cloud layers, which remained until I reached the Daggett VOR, only 80 miles from my destination. Finally, I was out of icing danger.

Pattern Ambush

Shorter days and longer nights are here: Have you brushed up on night flying? This new Never Again Online story illuminates the pilot's surprise as he launched for some pattern work during a moonless night.

Read this latest installment and other original "Never Again" stories published each month on AOPA Online.

I had made the 500-nm flight more than a hundred times in high-performance aircraft at cruise altitudes well above the 12,000-feet MEA, taking little notice of the terrain except for landmarks and position checks. Luckily, several subsequent flights at lower altitudes in my son's Piper Cherokee 140 had provided me with increased terrain awareness, a lifesaver on this trip.

When the ground- and airspeeds dropped, I had attributed this to frontal wind shift and a slightly iced up pitot tube. I neglected to search my mental checklist to rule out other causes and also failed to notice the three green gear-down indicator lights.

Finally, weather forecasts over a two-day period can change, and a report of 2,000-foot ceilings along a route does not mean the way is clear, especially when low visibility and icing are also forecast.

Alan Kris Widdison, AOPA 511320, is an instrument-rated commercial pilot and CFI.

"Never Again" is presented to enhance safety by providing a forum for pilots to learn from the experiences of others. Manuscripts may be submitted via e-mail to neveragain@aopa.org or sent to Editor, AOPA Pilot, 421 Aviation Way, Frederick, Maryland 21701.