Let's hypothesize that some Sourdough wants to build a grass airstrip on his property so that his Cheechako buddies can visit. Below are mistakes the former might make that the latter might encounter – to his peril. The list should give prudent pilots plenty of food for thought before they land on any private airstrip... or build one.
A visiting flyer could encounter problems if the airstrip is:
- Built on soft or clay soil with no underlayment and no camber for drainage, soupy in rain, rutted after a prior friend landed or a moose walked through, uneven shifting due to permafrost and ice heave.
- Studded with rocks that are loosened by each visitor, pitting propellers and low winged aircraft.
- Too short for visiting airplanes, or long enough to land but too short for visitor take offs when temperatures or humidity rise (leaving Cheechako Charlie a stranded, and possibly unwelcome, visitor until the weather changes).
- In many parts of the country, and CERTAINLY in Alaska, the runway will be wet, slushy, and icy many times of year. As any car driver in similar situations can imagine, the rule of thumb for safe landings in these conditions is to multiply one's "normal" landing distance by 1.4 when wet, by 1.7 for snow, by 2.3 for standing water/slush and by a whopping 3.5-4.5 for ice. PLUS a 15% margin of error. So, for example, a Cessna 182 and 206 generally can land in 1400 feet. However, ski planes have NO BRAKES unless one adds them (a $2000 extra). A safe ski plane pilot would avoid an icy strip of less than 5600 feet, especially if there are trees, roads, or homes at the far end of the luge lane, or if the strip angles downward. The past two warm winters here made strips perilously icy. Pilots avoided our neighbor's strip in the woods all winter long. They stuck to the much larger (if still icy) lake.
- Wide enough for the owner's plane or experienced pilots but too narrow for occasional pilots or in cross winds.
- Contains a tricky curve, laterally or vertically!
- Built steeper than the recommended 2% grade lengthwise or greater than the 2.5 % camber widthwise, or it angles down instead of up for landings, or the lay of the land changes over time and is not regraded by the owner. Oriented downward, a 1% grade can increase a pilot's needed landing distance by 10%. 3% grade = 30%! And who can see that from the air?
- Obstructed on the ends, sides, or even middle of the strip – a downed tree, a piece of machinery, animals, trash, a windblown plastic chair.
- Oriented toward the prevailing wind in some seasons but not others. Positioned where mountains throw up quirky weather. Positioned where landings speed up because of common tailwinds.
- Infrequently maintained if the owner is not a frequent flyer. For example, the grass could be high enough to obscure obstructions, ruts or animals except right before the owner/pilot plans to fly. Wet grass contributes to hydroplaning, while dry grass can "grab" on landing. (Where we live, the wild grasses grow one foot per week to eight feet and then flop over everything nearby).
- A windsock at ground level surrounded by trees/buildings will not offer much useful information, and it may be contrary to conditions above trees ... where you need it.
- Finally, most airplane insurance does not cover landings on private residential strips. Those visits are strictly “at your own risk,” understandably! The factors that most grossly exaggerate the length required for a safe landing are strips that are slippery (from ice, snow, water), where landings are graded downhill with a tailwind.
The owner of the airstrip may encounter problems he didn't contemplate, either.