Narrative:

After an uneventful practice session; I returned to my home field for some landing practice. My first landing was a short field and I brought the aircraft to a stop approximately halfway down the 3000 ft runway. I decided to conduct a short-field takeoff and set flaps 10. I set full power; held the brakes; and took off at the appropriate rotation speed. Thinking about how the elevator trim was set to full nose up and my first takeoff earlier in the morning where; despite elevator trim set to takeoff; I had to use considerable nose-down control pressure to stay above vy; I added some nose down trim in the takeoff roll. My liftoff and initial climb were normal; and as my airspeed exceeded 70 knots with a positive climb; I raised the flaps. At this point the nose dropped precariously and the aircraft started to descend to a small hill just off the departure end of the runway. Not wanting to stall; I did not immediately pull back on the yoke; but confirmed I had full power (I did) and quickly glanced down at my airspeed indicator. It showed 90 and I pulled back on the yoke; avoiding the terrain and associated obstacles; but had I not acted quickly in that moment; I'm certain the plane would have struck terrain at 90 knots. I'd estimate that I was less than 50 ft above the grass when the aircraft attained a positive rate of climb.the main contributing factor to this event was my decision to change the trim setting on takeoff and not verifying how I had it set. During my practice session; I had noticed that despite having full nose up trim; I felt like I was adding considerably heavier than normal control pressure to conduct steep turns and steep spirals. The combination of this; along with a slower than usual climb after my first takeoff; made me concerned about getting even slower on my short field takeoff. Taking off from midfield compounded the issue by giving me less runway to work with. I've certainly learned from this experience; and will not be making any configuration changes while on the takeoff roll.

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Original NASA ASRS Text

Title: C172 pilot reported a controlled flight towards terrain event shortly after takeoff due to a misconfigured elevator trim setting.

Narrative: After an uneventful practice session; I returned to my home field for some landing practice. My first landing was a short field and I brought the aircraft to a stop approximately halfway down the 3000 ft runway. I decided to conduct a short-field takeoff and set flaps 10. I set full power; held the brakes; and took off at the appropriate rotation speed. Thinking about how the elevator trim was set to full nose up and my first takeoff earlier in the morning where; despite elevator trim set to takeoff; I had to use considerable nose-down control pressure to stay above Vy; I added some nose down trim in the takeoff roll. My liftoff and initial climb were normal; and as my airspeed exceeded 70 knots with a positive climb; I raised the flaps. At this point the nose dropped precariously and the aircraft started to descend to a small hill just off the departure end of the runway. Not wanting to stall; I did not immediately pull back on the yoke; but confirmed I had full power (I did) and quickly glanced down at my airspeed indicator. It showed 90 and I pulled back on the yoke; avoiding the terrain and associated obstacles; but had I not acted quickly in that moment; I'm certain the plane would have struck terrain at 90 knots. I'd estimate that I was less than 50 ft above the grass when the aircraft attained a positive rate of climb.The main contributing factor to this event was my decision to change the trim setting on takeoff and not verifying how I had it set. During my practice session; I had noticed that despite having full nose up trim; I felt like I was adding considerably heavier than normal control pressure to conduct steep turns and steep spirals. The combination of this; along with a slower than usual climb after my first takeoff; made me concerned about getting even slower on my short field takeoff. Taking off from midfield compounded the issue by giving me less runway to work with. I've certainly learned from this experience; and will not be making any configuration changes while on the takeoff roll.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.