Date: 201905
Local time of day: 1801-2400
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 10
Light: Night
Aircraft: Skyhawk 172/Cutlass 172
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Takeoff / Launch
Airspace: Class G ZZZ
ATC / advisory: CTAF ZZZ
Reporter organization: Personal
Reporter function: Instructor; Pilot Flying
Reporter qualification: Flight Crew Commercial; Flight Crew Instrument; Flight Crew Flight Instructor
Human factors: Confusion; Physiological - Other; Situational Awareness
Anomaly: Inflight Event / Encounter Other / Unknown
Detector: Person Flight Crew
When detected: In-flight
Result: Flight Crew Became Reoriented
Contributing factors: Human Factors
Primary problem: Human Factors

Narrative: My fellow pilot and I (we are both flight instructors CFII) were doing a combined exercise in a Cessna 172SP. He was finishing his IPC and I was going for my night currency of 3 full stop landings and takeoffs. We went to nearby smaller airport to perform his approach and circle to land; which was done. Then I took the controls to take off from that airport to begin my night currency. It was official night and the runway was 28; to the west; 3;000 feet long; 75 feet wide with markings and edge lights. At the end of the runway; to the west; there was no developed area. It was completely dark with no horizon. There was no other traffic in the airport vicinity. One had just left the area. We exchanged the flight controls; I was in the right seat; and I took the runway. The aircraft landing light was on and the runway was visible. I held the brakes; set the flaps to 10 degrees for a short field takeoff; and applied full power; and then released the brakes and executed a short field takeoff; rotating at 54KIAS and climbing at 62KIAS. After climbing to 200 feet I retracted the flaps as normal. That's when the problem began; as the aircraft seemed to be climbing too much; and I lost my situational awareness; the aircraft descended; and the other pilot assisted me in recovering. I attempted again; and again the aircraft went from a climb to a descent and I asked the other pilot to take the controls; which he did. We then climbed and turned right; out of the traffic pattern; after which I took the controls again and flew back to home base; where I was able to perform the three full stop night landings there; with no further incident.Needless to say; it was a very disconcerting experience for both of us. Over all of my years of flying; which included flying at night; this had never happened to me. I believe what happened was a somatogravic illusion; where acceleration in IMC or night can make a pilot feel that they climbing too much; and they push forward when they shouldn't. The proper response is to concentrate on the instruments for attitude and airspeed. I should have absolutely relied upon the instruments.My plan to correct this is to fly in a simulator with the exact duplication of the conditions multiple times; with the same pilot who was with me; and then go out to that same airport with the same pilot in the aircraft and attempt to duplicate the same situation again; while performing the takeoff and climb appropriately; using the instruments for primary reference; example; with full power; rotate appropriately and pitch to 10 degrees; wings level; and then pitch for appropriate VX-VY. I will also hold on to the flaps a little longer; until we are more established in the climb. I will make sure that this will never happen again. It was a serious lesson learned.




Synopsis: C172 Instructor Pilot reported experiencing a possible somatogravic illusion while practicing short-field takeoffs at night.