With January almost over, you're probably becoming familiar with the hazards of winter weather - sounds like the perfect time for an accident.
Do You Know What's Down There?
Winter flying into unattended airports poses some special hazards, especially at airports that aren't heavily used. How do you know if the runway conditions are safe for your arrival?
Runway overflights are one of the most common methods to check runway conditions - but how well can you judge snow and ice depth from the air?
On December 10th, 2011, a Cessna 182 nosed over while landing in Lowman, Idaho. The NTSB report (WPR12CA060) paints a familiar picture:
"The pilot reported that he determined that the snow-covered runway was suitable for landing, based, in part, upon overflying it and seeing snowmobile tracks, which indicated to him that the surface was firm enough. After touching down on the main landing gear, the pilot held the nosewheel off the ground with full-aft elevator pressure, but, when the nosewheel settled, the airplane pitched down violently. It traveled for about 80 feet in the nose-down attitude before it abruptly nosed over, sustaining substantial damage to the right wing and rudder." (Emphasis ours)
How many times do you think the pilot had overflown runways and correctly gauged the snow's depth? I'm guessing more than once, and that he had been right most, if not all, of those times. This is not an isolated occurrence. NTSB report WPR12CA148 describes the same problem - the pilot used patches of grass and snowmobile tracks to gauge snow depth and ended up upside-down.
Visual cues can be misleading. How many times have you walked on snow only to sink down to your knees? So, what's a better way to check runway conditions? Call Flight Service and check for NOTAMs and pilot reports.
Flight Service Can Be Wrong
Flight Service can be great reference for runway conditions. However, they don't know the limitations of your aircraft and conditions can change over time. On April 9th, 2011, a pilot flying a PA-22/20 (Piper Pacer Conversion) into Talkeetna, Alaska found this out the hard way. From the NTSB report (ANC11CA023):
"The pilot reported that he contacted a nearby Federal Aviation Administration Flight Service Station (FSS) to ask if any airplanes had taken off or landed at the snow-covered, unattended gravel airstrip that was his destination. The FSS specialist stated that airplanes had landed there earlier in the day, but he did not have information about the runway condition. The pilot overflew the airstrip about 500 feet above the ground and it appeared to be hard packed, with signs of use. During the landing roll, the airplane's tires encountered soft slush and the airplane nosed over, collapsing the right wing lift-strut. The pilot said that there were no preaccident mechanical problems with the airplane and that he was unaware that the airstrip was used primarily by ski-equipped airplanes during the winter."
Flight service isn't at the airport, and while they can tell you if other pilots have reported conditions at your destination, they don't know if your aircraft or skills are up to the task. When using Flight Service and pilot reports as a reference, make sure to ask what type of aircraft were operating into the field and when the conditions were reported.
Even Maintained Airports Can Be Troublesome
Winter hazards aren't limited to unattended airports. While plows may clear runways, they may leave ice or slush on the surface - throwing a ground-loop into your landing plans. A pilot landing a Rockwell 690C Commander at Conrad, Montana ran into this problem on March 23rd, 2012. From NTSB report WPR12CA145:
"The pilot, who was executing a global positioning system approach to a non-controlled airport, saw a snowplow clearing snow from the runway as he broke out of the overcast in a light snow shower. Soon after the pilot spotted the snowplow, it exited the runway, and the pilot continued his approach/landing sequence. After touchdown, the airplane encountered an area of ice and slush on the runway and began to slide. The pilot stated that he should have initiated a go-around, but the airplane was never sufficiently realigned with the runway so he could safely apply go-around power. As the pilot continued his efforts to realign the airplane with the runway, the airplane departed the side of the runway and impacted a natural gas line warning sign. The impact with the sign resulted in a tear in the stressed skin of the fuselage that exceeded eight inches in length. The pilot did not report any mechanical malfunction during the accident sequence."
In this case, the pilot knew the runway had been recently plowed - he watched the plow leave the runway!
A similar situation happened when I was working at Atlantic Coast Airlines in 2003. One of our CRJs was landing at night in Bloomington, Illinois on February 14th, 2003. During rollout, it hit a snow and ice berm left by a plow. The front nose gear collapsed, but luckily the 29 crew and passengers escaped without injury. The NTSB cited several factors in this accident: the decision to land with a tailwind over limits, the failure to perform a go-around and instead landing long, as well as the snow contaminated runway. You can read the full narrative in NTSB report CHI03IA070.
Use Your Judgement
So - should you avoid flying during the colder months? Absolutely not! Use your judgement and do your research. Before departure:
Call the airport to check runway conditions.
Call Flight Service to check NOTAMs for the field and pilot reports from aircraft operating into and out of the field.
Consider how your aircraft and skills differ from others operating into the field. Are you more or less capable?
Consider how the weather has changed between when reports were filed and your arrival time. Sun can melt snow into slush, which can catch a wheel and quickly pull you out of control. And slush will freeze into ice as the temperature drops making directional control difficult and reducing braking action.
Perform a runway overflight at unattended airports, but remember that snow conditions can be deceiving.
If you feel the runway's safe for landing, stay on speed and select a suitable touchdown point. Use good soft-field technique and brake gently. If you feel uncomfortable or your approach isn't on target, practice a go around!
File a pilot report for the unattended airports you use. Whether the conditions are good or bad, other pilots will appreciate the information.
Winter flying can be a lot of fun, and with some caution and planning, you can stay out of the NTSB reports.
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