Black-Hole Approach to a Coastal Runway
A pilot is conducting a night visual approach to Runway 27 at a coastal airport. The runway is 1,800 m long at 350 ft elevation. The final approach is over dark water, and there are no lights between the aircraft and the runway threshold except a few distant town lights to the left. The runway has no VASI or PAPI. The pilot is at 3 nm, descending through 700 ft, and the runway edge lights appear bright and high in his visual field. He feels that he is too high, reduces power, and lowers the nose. The altimeter is unwinding faster than his normal profile, but he trusts his sensation because the runway looks close. At 1 nm he is low and slightly left of centreline. The surface wind is calm and the runway is dry.
1. Identify the illusion and explain why it produces a low approach.
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This is a black-hole approach. With no ground lights or visual texture between the aircraft and the runway, the pilot loses the normal cues that establish a horizon and a glidepath. The bright runway lights stand out against a dark background and appear higher or closer than they really are. The pilot interprets this as being too high, so he reduces power and descends. The result is a lower-than-normal approach, sometimes well below the correct glidepath. The absence of a VASI or PAPI removes an independent check. The dangerous feature is that the illusion feels convincing and the instruments may be the only reliable source of height and descent rate.
2. What should he have done before and during the approach to prevent this?
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Before the approach he should brief the black-hole risk, set a stable approach profile, and identify independent references: altimeter, vertical speed, distance, and any available RNAV or barometric vertical guidance. He should use the instruments as the primary glidepath reference and treat visual cues as confirmation, not as the sole source. If the airport has no glidepath indicator, he should consider a higher minima, a circling or diversion option, or waiting for daylight. During the approach he should cross-check altitude against distance at fixed points and call out deviations. If he feels high but the instruments show on-profile, he should not chase the sensation. A go-around is required if the aircraft becomes low, unstable, or laterally displaced.
3. During the go-around, acceleration makes him feel nose-high and he pushes forward. Explain what is happening and how to recover.
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This is the somatogravic illusion. Linear acceleration is sensed by the otolith organs in a way that can be interpreted as a pitch-up, especially when there is no clear visual horizon. The pilot may push the control column forward to correct a nose-high sensation that does not exist, causing a dangerous descent or ground contact. The recovery is to recognise the illusion, ignore the false sensation, and fly by reference to the attitude indicator and airspeed. He should establish a positive climb, set go-around power and pitch, and maintain instrument cross-check. If he has a second pilot, he should call the attitude and airspeed aloud. He should not re-attempt the visual approach until he is stable and has a clear horizon or instrument guidance.