Delta Air Lines Flight 554: Undershot Landing

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Synopsis

The undershot landing occurred at LaGuardia Airport, New York, on 19 October 1996 (NTSB, 1997^[2]). During the landing on runway 13, the Delta Air Lines McDonnell Douglas MD-88 aircraft struck the approach light system and runway deck structures (Dismukes, 2007^[1]). Due to the great impact, the main landing gear separated from the aircraft body, leading to the sliding of the aircraft down the runway on its fuselage belly (Dismukes, 2007^[1]). As a result, the lower fuselage was substantially damaged and three passengers injured (NTSB, 1997^[2]).

Main Cause

Captain’s Use of the Monovision Contact Lenses¹
The use of monovision lenses led to misconception of the distance between the aircraft and the runway during approaching (NTSB, 1997^[2]). Normally, in the form of binocular vision, the brain fuses the two images from two eyes into a single three-dimensional image, aiding in the depth perception² (NTSB, 1997^[2]). However, when using monovision contact lenses, the brain would be unable to fuse the disparate images, causing degraded depth perception (NTSB, 1997^[2]). Therefore, the use of monovision lenses along with the special design of the runway and the environmental conditions gave the captain a wrong perception that the runway was more distant and the aircraft was higher than it was, thus, he descended steeply before the impact, leading to the accident (NTSB, 1997^[2]).

Remedial Actions

1. The optometric associations should inform all the optometrists that the pilots’ use of monovision contact lenses was prohibited and encourage them to advise pilot-rated patients of the related hazards of wearing monovision contact lenses (NTSB, 1997^[2]).
2. Delta Air Lines should take the responsibility to inform all pilots about the prohibition of the use of monovision contact lenses through internal guidance (NTSB, 1997^[2]).

References

1. Dismukes, R. K., Berman, B. A. and Loukopoulos, L. D. (2007). The Limits of Expertise: Rethinking Pilot Error and the Causes of Airline Accidents. England: Ashgate Publishing Limited.

2. National Transportation Safety Board. (1997). Aircraft Accident Report: Descent below Visual Glidepath and Collision with Terrain, Delta Air Lines Flight 554, McDonnell Douglas MD-88, N914DL Laguardia Airport, New York, October 19, 1996. Washington DC: The Board.

3. Civil Aviation Authority. (1998). Aviation Medicine Manual. England:Westward Digital Limited.

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Footnotes

1. The monovision contact lenses apply distant vision correction to one eye, and near correction to another eye. They are not approved for use by pilots while flying (NTSB, 1997^[2]).

2. Depth perception depends on the relation, size and clarity of objects, on relative movement and on texture detected through binocular vision normally (CAA, 1990^[3]).