Final answer:
A lack of approach lights at rural airports at night can create an illusion for pilots that they are at a higher altitude than they truly are, known as a 'black hole approach'. Pilots are trained to overcome this by relying on flight instruments and following standard procedures.
Step-by-step explanation:
When approaching an airport at night in a rural area with very few approach lights, pilots may experience an optical illusion of being at a higher altitude than they actually are, due to the lack of visual cues and reference points that are normally provided by denser lighting around urban airports. This optical illusion is known as 'black hole approach' because the darkness of the surrounding terrain can create a perception that the airplane is higher, which can lead to a lower-than-normal approach and possibly a risk of undershooting the runway. Pilots are trained to rely on their flight instruments rather than visual judgment during these approaches, using standard instrument approach procedures to ensure a safe landing.