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Landing and Takeoff Techniques for Rough Strips
by George Loegering, rev 04/20/03

In arguing with Caltrans for a packed gravel runway specification it was determined that unpaved public use airports in California are or were a rarity because of possible state liability. Aside from old time bush pilot friends not many aviators go looking for non-paved runways and ramps; especially if they are flying an expensive tricycle gear aircraft. However with a little luck and proper technique soft, wet and rocky strips can be safely utilized even with a Bonanza or Baron so they need not be categorically avoided.

As memory serves, the last California gravel strip I flew into with my Bonanza was Shannon in Trinity County. Shannon was a small ranch strip near Zenia. When the Shannon's sold the property to a Silicon Valley VP with a Baron he also bought the strip and did not renew the lease with the county. He named it Heller-Highwater; it is now not on the charts. There are (were) many other remote, private use or restricted strips in California and other flying destinations. Typically, unimproved strips have uncertain maintenance and are subject to unusable periods due to damage, vandalism or after inclement weather as well as other hazards including being uphill, short, narrow, dog-legged, poor approaches, no go around, etc.

I have been into many unpaved strips in foreign countries and other states with minor problems. I did get some very nasty propeller damage at a strip in Alaska in 1967 but cut off the tips and filed it out for a safe departure. The main part of that strip was leveled with a 4x4 old military truck over river run 1 to 2in diameter round stones with some 10 inch deep furrows. Landing and takeoff were no problem; my mistake was trying to taxi. My favorite (bad) strip is near Scammons Lagoon on the west coast of Baja California. That strip was eight feet wide, 1800 feet long and 6in deep (sand). A buddy took a lightly loaded C-172 rental in for the first landing since we couldn't get any current reports. We landed the A-35 Bonanza with 4 persons and a rubber boat. The 172 had a small outboard motor. During that day two other planes, including a C-195 landed to look around; monkey see, monkey do! We had a great day but that's another story. The early model Bonanzas are lighter and came with larger main tires than the later models (always have good tires); these are more suited to unimproved stripes.

Whether it's soft sand, mud, wet/tall grass, loose gravel, large rocks or potholes, unimproved landing sites are at your own risk. Circling or a low pass to do a final check of field conditions should always be done however I would normally not even be there without a good recent report by someone on the ground able to judge the airstrip condition for your aircraft. If you are planning to land at an unimproved strip minimize and secure your load before departure. If possible do a close in fly-by; check for uphill, and obstacles such as rocks, fences, dips, washes, then factor in the wind. Most importantly you need to make sure that you plan a good approach to the favored end (sometimes there is only one end). If forced to land downwind or with a trailing crosswind do not bounce it in as this scenario can cause loss of directional control at a critical time. If there is sufficient width plan to land on the side to best compensate for crosswind drift but pick a smooth touchdown spot and then consider where you are going to park/turn around as you may want to carry a little momentum to avoid a high power taxi (ala landing on a glacier). Obviously you want a power-on full flap slow approach when you decide to commit to the landing. Don't rush to make your approach and carefully consider all your options, I once had the winds change from a 30 knot crosswind to near zero wind by waiting a few minutes. Another time the 30+ knots was not going to abate so I landed on a newly graded parking area lined up with the wind, the wind more than compensated for the short length.

After having landed hundreds of times on unimproved strips my experience shows that the touch down and roll out are generally as smooth as with paved strips. Sometimes braking is not needed and sometimes braking is either not recommended (keep the controls aft as needed to keep weight off the nose wheel) or not good till very low speed; so don't rely ! a lot on braking except for slow turns. Braking is usually more affective without flaps and they are less prone to rock damage when retracted but don't rush them up at the risk of retracting the gear or losing focus on landing. After landing hand tow the aircraft to parking if in doubt as to holes or soft sand or other terrain problems (may take several people with ropes). Bring ropes and good tie down cleats; I like the foot long screw-in dog stakes available at K-Mart.

Takeoff can be easier if you are lightly loaded and there is a paved takeoff pad. You also have the advantage of being able to walk the runway and choose the departure time of day. Always walk the runway and make lots of noise to get varmints and deer out of the area; critters can be a very dangerous distraction. Similarly, you do not want to practice soft/short field takeoffs/landings in an inherently primitive area., do this right, do it once. Before starting the engine try to remove loose 3/8 to 3/4in rocks in the first 20 feet out front of the prop-if this is impossible, all the more important to use minimum RPM at start-up, have the plane tires out of ruts and facing downhill, if possible use the engine start to immediately start rolling. If a run up area is not available do not run up in the dirt standing still, run up while taxing and any rocks sucked up by the prop will generally tend to miss the blades. If there is any doubt, I have occasionally not done the run up-losing a part of a prop blade is a lot worse than possibly having only one magneto or the prop stuck in high pitch. The typical takeoff with no run-up pad is on the roll but be absolutely sure that you have accomplished a good preflight and that the engine is properly warmed (this may require that you do a warm up and preflight in a cleared area before you start moving with minimum RPM).

Use some flaps, hold the wheel all the way back initially with a slow release of the back pressure as speed builds. Acceleration can happen quickly if lightly loaded so do some practice. I usually use 1/3 flaps on gravel, a little over 1/2 on slush, snow or water and near full on wet/tall grass with a little less flap if a strong crosswind. Mud, slush and water may require "bouncing" to break the suction in order to reach takeoff speed. Each situation is a judgment call and depends on lots of variables including loading, pressure altitude, winds, runway width/length, obstructions, etc. If possible mark a takeoff abort location during your walk inspection of the strip and execute if things are not going right on takeoff. Retract the flaps slowly after reaching climb speed or as required. After departure, if the weather is cold and the strip wet, consider recycling the gear to minimize water/debris freezing in the wheel wells.

Experience has shown me that most rough field operations can be done safely with great satisfaction but there are times when no one is going anywhere until conditions are right. Be sure when you land that you will have sufficient options to depart. I have found that the landing distance was sometimes very short, no sweat; however, takeoff was not so easy. I will not forget the muddy farming strip just south of Mexicalli that my buddy, who had hunting rights, wanted to checkout for bird hunting. It looked excellent from the air but had a light dry crust disguising the subsurface muck from a very heavy rain a week before; a current report from the ground would have prevented a potentially hazardous operation. Watch out for those rocks!!