Obvious Hints

Loose items were flying around the cockpit and our heads were hitting the canopy


I never should have learned this lesson because I never should have made the flight. Mother Nature decided to demonstrate several of her most unnerving weather phenomena.

We were planning a flight from Los Alamos, N.M., to Amana, Iowa, for a weekend fly-in. We expected wind over the entire area of the flight for most of the planned weekend. Because of the length of the flight, we planned to leave Thursday so as to be rested when the festivities began.

The Los Alamos airport is at an elevation of 7,150 feet and is a one way airport. Takeoff is to the east and landing to the west, regardless of wind. As we drove to the airport from about 30 miles west of Los Alamos, the wind was causing the trees to thrash about wildly, but we werent too concerned because this was 2,000 feet higher than the airport.

However, the wind continued as we got down into Los Alamos and to the airport. This should have been our first clue as to what potentially lay ahead.

We departed with a 12- to 18-knot tailwind, not our favorite takeoff conditions. Our planned route of flight is to cross the Sangre de Christo Mountains south of Taos, over Angel Fire, and north of Cimarron, at 11,500 feet. We were enjoying a tailwind of about 30 knots before crossing the mountains. We experienced the normal bumps over the mountains, then light turbulence as we headed northeast toward our fuel stop in Harlan, Iowa. A high overcast existed above us, but visibility was unlimited. The tail wind had increased to about 55 knots.

We were past the mountains by about 20 to 30 miles when all hell broke loose. Loose items were flying around the cockpit and our heads were hitting the canopy. I focused on maintaining attitude and not worry about deviations in altitude or direction. We were in an area of severe turbulence.

The VSI was pegged at 2,000 feet per minute, first up then down. The airspeed quickly accelerated well into the yellow arc and I reduced power considerably.

I have no idea of how long this situation lasted but it must have been several minutes – although it seemed like hours. Just as quickly as it arrived, we entered an area of light to moderate turbulence and we were able to return to controlled flight.

But the weather wasnt done with us yet. We then had to fly through a periodic series of rising air followed by down drafts. We probably experienced about six of these waves.

Finally we realized we had flown into a mountain rotor, followed by a series of mountain waves. There was nothing in the forecasts or anything observable to warn us of the possibility of mountain rotors. However, with the strong winds out of the west and the mountains behind us, we should have been alert for the possibility of the rotor.

When we arrived at Amana, we were greeted by 20-knot winds 90 degrees off the runway.

The flight home on Sunday had some additional challenges. Forecasts called for a line of strong to severe thunderstorms in Kansas and Nebraska. We hoped to be able to stay east of the line and then around the southern end. They were marching eastward at about 45 knots.

When we landed for fuel in Harlan, the clouds consisted of a thin widely scattered layer at about 3,000 feet. In the 20 minutes it took to get fuel, the clouds began moving in. We opted to depart VFR to avoid potential thunderstorms. We had to fly somewhat eastward to stay VFR, but now the cloud tops were at about 10,000 feet.

We headed southwest, but the cloud tops continued to rise, pushing us up to about 12,500 feet. Flight Watch said the line of thunderstorms now extended from western Oklahoma well up into Nebraska.

We were over Concordia, Kan., well east of our planned flight path, when we decided our day was over. We filed for an IFR descent into Salina, Kan., only about 40 nautical miles away. As we circled down from 12,500 feet to 4,000 feet for the approach into Salina, we noted our ground speed sometimes was reduced to about 30 knots.

Center continually requested position reports, as I am sure they thought we had parked. When turned over to tower, we continued to get requests for position. We landed without incident after what seemed to be an infinitely long approach.

We asked that the airplane be hangared for the night for fear of hail. The night before a nearby small town was demolished by a tornado. We only saw very heavy rain but were thankful for the hangar.

Ive had some mountain flying training, but now I see the need to get more. I knew of the existence of mountain rotors and mountain waves, but I never tied together the rotor potential with the strong upper level winds over the mountains, and wrongly thought that once out into the plains that our troubles were over.

The conditions were ideal for what we had experienced, had we only took some time to think about it. Mother Nature does, indeed, have plans for the unwary, and the unobservant.


Out for Ice Almost Came Up Short
Im a 2000 plus-hour instrument rated pilot who commutes weekly by normally aspirated Mooney 201J between the UK and the Continent.

Summer and winter, theres ice at IFR levels in these North Sea climes. Ive seen it in all shapes and sizes. The base of most UK airways is above, sometimes well above, 6000 feet. If I adhered to the most conservative rule about flying when icing was forecast, Id hardly ever fly.

So I have developed my own golden rule: If theres visible moisture forecast (which is always) and the freezing level isnt 2000 feet agl or higher, I dont go.

My usual strategy is to get up to the -15 C to -17 C level fast and hopefully get on top or find a layer so I can see what Im doing. But no matter how knowledgeable one is about ice, where its likely to be and how to avoid it, the danger is that overconfidence plus an incorrect forecast will combine to spoil the day.

On a recent flight behind a cold front – but not traversing the front – I intended to get high enough to be able to see and avoid the towering CU and CB. Tops were supposed to be at 8,000 feet, and I was prepared to go on oxygen in order to go up to 12,000 or even 16,000 feet.

But controllers refused my request to turn right to avoid a buildup and I found myself climbing in CU. By the time I got to 14,000 feet I had a quarter-inch of ice on the leading edges and not enough power to go higher.

The OAT was an ominous -10 C, not the -15 C forecast. I remained in the murk, and the tops that had previously been at 10,000 feet now seemed to stretch up into the 20s.

As ice collected, I dawdled. Should I wait and hope to get out of IMC, or should I go down? Over the next 20 minutes, the leading edge layer built, the ice turned from light rime to mixed, the prop buzzed intermittently from ice and the IAS slowed perceptibly. There is an minimum IAS at which I act, and as it approached I asked for lower.

It took ATC what seemed an eternity to give me a lower level. Although I could increase speed in the descent, the ice accretion got worse, not better. By the time I got to 5,000 feet and -2 C, my Mooney looked like a snowball. The freezing level was at 4,000 feet but the wing ice (and, worse, probably the unseen tailplane ice) didnt budge. Even at full power the controls were mushy flying straight and level.

It was only when I descended to 2,000 feet and +2 C that the ice finally began to shed. I flew the last 100 nm well below the airway and barely above the minimum safe altitude in turbulence and heavy showers.

Had the minimum altitude for that sector been higher, had the freezing level been lower than 4,000 feet, had there been moderate turbulence higher up…

Its nice to have the luxury of speculating in retrospect. The one certainty is that if you fly in cold climes long enough, youll have an icing encounter in which the only way out is down. There has to be a means of escape below. My 2000 feet agl rule over all legs has been revised upward.


Digital Tach Saves the Day
For various reasons, many pilots and avionics gurus question the wisdom of installing a digital tachometer.

My Cherokee 235s panel includes the Horizon P-1000 digital tach as a replacement for my primary tach. Ive flown with this instrument for several years now, and have found it phenomenally accurate, easy to use, and very reliable. But it wasnt until this week that the instrument really paid for itself.

En route back from a day at the beach under VFR, I noticed the Horizon tach was flashing an amber warning light, indicating that the two mags were sending inconsistent information. The engine continued to run fine, but clearly something was wrong.

As soon as I landed, I asked the local mechanics to troubleshoot the problem. They found that the P-lead on the left mag was chafed and shorting out against the firewall. That was causing the anomalous reading on the tach.

The problem was intermittent and didnt show up on the ground, only in cruise flight. We suspect the wind pushed the wire against the firewall. Grounding of the P-lead, of course, would eventually have resulted in magneto failure.

Needless to say, a mechanical tach would not have detected this problem. But thanks to the digital tach, we were able to find the problem before it became more serious.

Of course, the Horizon digital tach does a lot more, too. It detects the failure of a mag and lets the pilot know which mag failed, so that he can switch over to the good mag. And it automatically calculates mag drop during runup.

Safety features like these are the most compelling reason to switch to a digital tach, in my opinion. The fact that the Horizon only costs about $500 is icing on the cake.


You Sound Mah-velous
As a very low-time student pilot, I was practicing landings on a perfectly clear but busy weekend at a non-towered airport in a Cessna 152. I was proud of my recently acquired phonetic alphabet and the associated radio av-speak.

There were anywhere from eight to 10 aircraft in the pattern at any given time. On my sixth trip around the pattern, I was on left downwind and reported my base turn. The turn was directly over town, making it difficult to spot traffic.

Just then another aircraft reported turning final, but I could not see him. I figured he was ahead of me and, since I had just turned base, I continued on without a worry.

When I called my turn to final, the other pilot said he, too, was on final and wanted to know if I could see him. He sounded frantic.

I told him I was on very short final and I now suspected he was behind me. He was very excited and yelled he couldnt see me. He said he was going around.

I was astonished to see his airplane suddenly emerge from underneath me.As a student pilot, the message to me was clear: When in the pattern worry less about how you sound on the radio and listen carefully to other traffic. Even though the other pilot should not have done a low instrument approach with so many airplanes in the pattern, he had the right of way over me. Im glad he was paying attention.


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