Every pilot looks forward to broadening his flying experiences, both in terms of skills and geography. Over time he will encounter runways of different lengths, widths, surroundings and surfaces.
Most of us who have learned to fly in recent years are accustomed to well surfaced runways of excessive length for the airplanes we fly. Should we find ourselves faced with a runway nearer to the limit for our airplane, we need to consult our performance charts and understand their limitations. We must also understand that nonstandard elements will effect our landing and take off performance. Runway surfaces such as turf or gravel, runway condition and slope, wind, density altitude and aircraft weight all effect performance. Soft ground, tall grass and runway slope will retard acceleration, sometimes to an unpredictable degree.
Although not a substitute for performance charts, a “rule of thumb” calculation can be helpful when taking off from a nonstandard runway. Assuming the runway length is appropriate for take off we should achieve at least 70% of lift off speed before reaching the midway point of the runway. If there are obstacles to be cleared, the rule may have to be reduced to less than 50% of runway length for 70% of lift off speed.
Rules of thumb and performance charts are useful guides, but one must know his airplane. In consideration of the vast number of variables for take off, calculations should be tested on practice flights and compared to actual performance. Learn how to adjust your estimate for various factors. This form of practice is an excellent way to familiarize yourself with your aircraft and prepare for any future encounter with unfamiliar or unimproved airfields.
*Please review club policy on unpaved fields and runway lengths.
Reference: Plane & Pilot March 2003 Ron Fowler
These safety tips are provided by the WCFC Safety Committee. They are intended to stimulate thought and discussion about flight safety and do not necessarily represent club policy nor are they intended to replace instruction from a qualified instructor.