Somatogravic Illusion on a Night Go-Around
You are conducting a night departure in a light twin from a coastal airport with an unlit black hole beyond the runway end. At 400 ft on the climb-out the tower instructs an immediate level-off at 1,500 ft for crossing traffic. You apply power reduction and lower the nose briskly to arrest the climb. Immediately you feel strongly that the aircraft is pitching nose-up and you have an impulse to push forward. The attitude indicator shows approximately 5 degrees nose-up, the airspeed is increasing through 130 kt, and the vertical speed indicator is settling toward zero. The first officer is head-down briefing the approach and has not looked outside.
1. Identify the illusion and explain the mechanism producing your sensation.
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This is the somatogravic illusion, a false pitch sensation generated by the otolith organs. The otoliths are small hair-cell structures loaded with crystals that respond to the resultant of gravity and acceleration, not to gravity alone. In steady flight the resultant points down and the brain interprets it as vertical.
When you reduce power and lower the nose, the aircraft decelerates in the forward axis. The resultant force now tilts forward relative to the head, and the otoliths signal a change that the brain interprets as a pitch-up rotation, because a true pitch-up would produce a similar otolith pattern. The result is a compelling sensation of climbing while the aircraft is actually descending or levelling. The black-hole departure removes the visual horizon that would normally override the false signal, and the brisk control input maximises the transient.
The impulse to push forward is the dangerous part: acting on it would steepen the descent toward terrain. The attitude indicator and airspeed trend are the valid references here, and they show a nose-up attitude with accelerating speed, consistent with a level-off, not a climb.
2. State the immediate control action and how you would manage the crew and the remainder of the departure.
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Immediate action: do not push. Cross-check the attitude indicator, altimeter and airspeed, and hold the attitude shown on the instrument. Announce the illusion aloud: 'Somatogravic illusion, I have it, instruments are valid, holding attitude.' Verbalising it breaks the loop between sensation and reflex and recruits the other pilot.
Crew management: ask the first officer to lift their head and monitor the flight instruments and altitude callouts, since a second set of eyes on instruments is the best defence. If workload permits, engage the autopilot for the level-off so the aircraft is flown by a reference unaffected by your vestibular system, and confirm the mode.
For the remainder of the departure, brief that any further acceleration or deceleration (level-off, configuration change, speed reduction) can reproduce the sensation. Maintain instrument reference until clearly established in visual conditions with a visible horizon, and avoid large power or pitch changes close to terrain. Report the event if it affected the flight path; it is a reportable hazard in many states and a useful learning point.