Proficiency

Precautionary Tales

February 1, 2006

When landing to "look-see" is the best option

An emergency clears the decks. You distill possible actions to address the task at hand — correcting the problem or getting the airplane safely on the ground. But what about a problem that's not so imminently threatening? Or one that doesn't seem that serious? Do you continue the flight, hoping to make it to your destination without the situation deteriorating, or do you make a precautionary landing and take a look-see?

When we asked AOPA members to share their tales of similar events, all expressed satisfaction that their decisions to stop and check into a problem were sound ones — regardless of the outcome. And many credit the precautionary landing with helping them avoid an emergency, with its more serious consequences. In fact, it could be one of the most important pilot-in-command decisions you make — a display of initiative rather than undue caution.

Fuel precautions

One really good reason to cut a flight short of its intended destination crops up when your fuel reserve falls low — whether by a change of winds and weather, a simple miscalculation of fuel burn, or an operator error.

"My wife and I took our first cross-country flight in a Diamond DA40," says Douglas Hansell, AOPA 3972199. "Our first leg was from Smyrna, Tennessee, to Concord Regional Airport outside of Charlotte, North Carolina. We leveled at 7,000 feet...the GPS reminded me to switch tanks every 15 minutes, and I dutifully complied.

"As we neared eastern Tennessee, I noted that the electronic fuel gauges read lower than I expected, and I realized I had neglected to lean my [mixture] to the recommended fuel flow of 9.5 gallons per hour. Instead I had been gulping down 15 gph for nearly two hours.

"I took a few minutes to calculate how much fuel I thought I had remaining in the tanks, though I was not completely confident what my fuel burn had been. Knowing how busy the Charlotte area can be and considering the possibility of diversions before reaching our destination, I decided to land at the nearby Tri-Cities Regional Tennessee/Virginia Airport to refuel.

"As it turned out, we had plenty of fuel on board to continue to our destination. However, our precautionary landing saved me 45 minutes of anxiety."

Sounds like a great reason to land and assess the situation — even if the situation turns out to be less dire than originally thought.

Mechanical maladies

Far and away, suspected (or obvious) mechanical problems were the most cited reason for making a precautionary landing among members who responded. Avi Weiss, AOPA 1142053, recalls his experience with a nagging engine problem that didn't resolve itself on his first precautionary landing — or his second.

"I was on a long cross-country [flight]...to Red Bluff from San Jose, California. I noticed that no matter how I set the mixture, I couldn't get the engine to run perfectly smooth like it normally did. The best I could get was a low rumble. The speed, temperature, and pressure all appeared as usual. I made it to Red Bluff just fine. No mechanic was available, so I ran it up, leaning during runup, figuring that there was fouling of the plugs. The engine ran smoothly after a few minutes.

"About 20 minutes after takeoff, the roughness started in again. I decided to land in Chico to figure out what was going on. After landing, I went to run it up, and a mag check had the engine dropping 250 to 300 rpm and running really rough. I taxied in and called the FBO [from which I had rented the airplane].

"They were not pleased. I said I wouldn't fly it in its condition. After a long wait, the FBO's maintenance guys arrived, pulled the plugs, and indeed some of them were very fouled. After a field cleaning and regapping, they put them back in, and, after running it up, declared the airplane fit to fly home.

"With 30 minutes left [on the leg home], the engine began running rough again. As a precaution, I had already climbed to 10,500 feet. I stayed at 10,500 as long as possible. I let San Jose Approach know I had a rough engine, and wasn't sure if once I pulled power back whether I would get it back again. I pretty much glided to San Jose, and after landing, confirmed that the plugs were again very fouled.

"Turns out the rings on a couple of cylinders were going and the compression on the cylinders was well below acceptable limits. This led to improper combustion and the resultant instant-plug-fouling mixture."

The moral of the story? Get a problem resolved to your satisfaction — and keep the deck stacked in your favor until you're sure of that resolution.

'Does the engine sound funny?'

No one wants to hear words like these — either from that little voice inside or from a passenger. "I had been eyeing the oil pressure gauge for some time, trying to convince myself it wasn't really moving toward the low side," recalls Carlos Contreras, AOPA 745306, remembering a flight in a Piper Turbo Lance from Mackinac Island, Michigan, to Chicago on a direct route that took him well offshore over Lake Michigan. "Yet my flight path was now edging closer to land instead of the more direct route toward our destination. We stayed at our cruising altitude until within gliding distance of land, and made an uneventful landing [at Racine, Wisconsin]. That is, until the low oil pressure light came on while taxiing in.

"We found a mechanic who uncowled the engine, and looked around, with the engine running, but found no obvious leaks. We added several quarts of oil just to get a reading on the dipstick, and figured we probably had three quarts left at landing. I called the owner, who convinced me that I had probably not seated the dipstick correctly. We took off again.

"After two hours of flying [to return to Meigs Field in Chicago] the [oil] was two quarts low. I knew I had seated the dipstick properly, and that I was being the dipstick if I continued flying the airplane." Contreras reports that less than a month later the airplane crashed following an engine failure.

Earl Whyde, AOPA 1500703, a Learjet pilot, sums it up well: "When you think the aircraft or engines are coming apart, no-brainer." But even a nagging feeling that something isn't quite right is better addressed on the ground.

Lois Mermelstein, AOPA 1345302, gives us her experience, "because there were so few overt symptoms" of the true problem, she says. About equidistant from San Antonio, Corpus Christi, and McAllen, Texas, (her destination) on an Angel Flight mission in a Mooney, Mermelstein "happened to notice the bars for cylinder number two on the [aftermarket] engine monitor were flashing. The cylinder head temperature on that display was also reading way high. The factory-installed CHT and exhaust gas temperature gauges were normal...all the other engine gauges were normal too.

"I did cooling things: throttled back a bunch, richened the mixture; the bad CHT came down a bit, and stopped flashing. I went back to full throttle — it started flashing again. I found a manifold pressure that didn't cause flashing and left it there."

Both Corpus Christi International and San Antonio International airports were of equal distance away, but Mermelstein was more familiar with San Antonio so she announced her plan to divert there to air traffic control. "I was vectored basically over Stinson [Municipal], and breathed a sigh of relief since I knew I could land there if I had to, but I still had power and altitude so I continued.

"Sometime in the descent and vectors for the visual [to San Antonio] the engine monitor alarm sounded again, even at the reduced power setting — I decided I was not going around." Diagnosis: One of the rings was stuck on the piston. "Turning around when I did probably saved the cylinder [from needing to be] overhauled."

From precaution to necessity

When the manifold pressure on his Cessna T210 dropped suddenly from the top of the green on the gauge to 24 inches during a climb through 3,500 feet, Robert Riddle, AOPA 896653, knew something was wrong. "I added throttle and watched the needle climb to the original setting. We continued to climb [out of the Salinas Valley, California, en route to Santa Maria], and as we did, the manifold pressure dropped with increasing altitude.

"The wastegate controller should have compensated for altitude. I looked at the terrain ahead of us — ridges, chaparral, and very few houses and roads for at least 30 miles along our route. Three miles ahead there was a short [private] dirt strip. It would be long enough to take off on if we needed.

"I was circling and bleeding off power, and got set up on a long final. I had the runway pretty well made and looked again at the gauges — the oil pressure was dropping fast. I cut the engine as soon as we touched down.

"Oil was dripping out of the cowl flap openings and there was a puddle already forming on the ground. We had ruptured the high-pressure oil line that actuates the wastegate controller for the turbocharger. Ten to 11 quarts of oil had blown out of that line in the five minutes I made up my mind to land." Riddle's advice? "Take control of the situation before the situation takes away your chance."

Weather changes

The weather also can provide the reason for a precautionary landing — in this case another term for the "diversions" we learned back in primary training. While crossing the country in her Great Lakes 2T-1A-2 biplane, Anne Hopkins, AOPA 1009657, encountered weather that caused her to land short of her goal. "I had no schedule set in concrete," she recalls, "so there was no time pressure weighing on any decisions. The forecast was VFR, but with some patchy rain and mist, improving throughout the day. I had never flown in this area before [from Frederick, Maryland, en route to Morristown, Tennessee].

"I launched, expecting to slalom down the Shenandoah Valley at 500 to 1,000 feet agl. By the time I hit Harpers Ferry [West Virginia], I began thinking I should have just rolled over and stayed in bed. The ceilings were dropping, and some worrisome wisps of wannabe clouds just above my 800-feet-agl path grew larger and more frequent.

"Luckily, I could see Front Royal airport [in Virginia]. I hung a right onto final, and, as the airport manager told me later, 'It was just like out of some book, this pretty little airplane just dropped out of the sky on us.' What I expected to be a few-hours' wait stretched to overnight — twice." (You can read more of Hopkins' biplane tales in her book, Sticks & Wires & Cloth, available through Trailing Edge Publishing at www.tebooks.com.)

From the flight levels...

Michael Millsap, AOPA 1165726, flies about 650 hours a year in a Beechcraft King Air C90B, and last June he found a concrete weather reason to discontinue his flight from Mississippi to Texas. "Afternoon heating and a small front had built a solid line of weather along my normal route. I had even briefed my passengers that we may have to stop en route if there were no 'holes' to fly through. Since these storms were topping out at 50,000 feet, going over was not an option.

"As we approached Monroe, Louisiana, to pick up the arrival into the Dallas Fort Worth Metroplex, the storms were fast approaching. Though I was on an IFR flight plan, I simply advised ATC that I would need to land in Monroe to wait out the weather. ATC was glad to accommodate, even though I was only 15 miles from Monroe at FL200. Amazing how much altitude you can lose in a couple of three-sixties.

"The landing was uneventful as the weather and I both approached the field. As we taxied to the ramp the wind shifted and the rain began to fall. Less than an hour later we were back in the air to continue our journey home."

...to the low levels

In June 1969, John Potter, AOPA 279262, got permission to fly a Piper J-3 Cub from Bainbridge, Maryland, to Fredericksburg, Virginia, each weekend to see his fiancee.

Potter recalled one early morning return trip to Maryland when the freeway he usually relied on for navigation was getting hard to follow because of weather — just as he approached the more-congested area just south of what is now the Baltimore/Washington International Thurgood Marshall Airport.

"I suppose," Potter says, "that this was indeed 'scud running,' but in a J-3, these were normal low-level operations — except when you get so low that you might as well land. I was skirting around BWI with all of its IFR traffic, so I just picked an open patch alongside the freeway and set down to wait until the ceiling lifted. That was the 'precautionary' part; the rest was comical.

"I taxied up behind a lady picking vegetables. She was very startled, and...a protective crowd gathered from her clan. After she settled down a bit, she allowed me to use the phone. I went on my way a few hours later, but what a wonderful visit I had with some people who were truly hospitable and warm, and who readily shared what little they had."

Which just goes to show that, even if you make a precautionary landing for naught, you'll most certainly be better off for the experience.


E-mail the author at julie.boatman@aopa.org.


Links to additional information about precautionary landings may be found on AOPA Online.


Make the Precautionary Landing

Here are the steps to follow should you find yourself in a situation that begs for a precautionary landing.

  1. Assess the risk. Your relative risk depends on your experience and qualifications. Are you a VFR-only pilot with low time in the model or an instrument-rated pilot in the airplane you've owned for a decade? More experience means more options — but sometimes means a greater feeling of "I should be able to handle this" when, really, you don't want to go any farther.
  2. Find an airport. Taking the precautionary step usually means you can choose an airport for your unplanned stop. If your flight planning doesn't offer many options, resolve to find more options next time.
  3. Choose your poison. If no airports exist and the situation demands that you land, remember that it's far better to pick out your off-airport landing than to let the situation deteriorate further. Enter a pattern as you would at a normal airport, and if you can, make a low pass to assess the conditions. Keep an eye out for wires, poles, and other obstructions.
  4. Practice soft-field procedures. Use a power-on approach to control your descent rate, and a steeper-than-normal final to manage obstacles. Plan for a full-flap landing at 1.3 VSO. Touch down on the mains first, and hold the nosewheel off as much as possible to reduce the chance of cartwheeling or nosing over — use power if necessary. — JKB