Controlled Flight into Terrain

Introduction

The aviation community generally defines CFIT as "...any collision with land or water in which there was no detectable mechanical or equipment failure, where the pilot was in control of the aircraft but lost situational awareness and flew into terrain." (Bensyl, Moran, Conway, 2001, pg 1037) According to the National Transportation Safety Board (NTSB), the Federal Aviation Administration (FAA) and the Flight Safety Foundation (FSF), CFIT can be caused by many factors. Nevertheless, it is primarily caused when a pilot or flight crew is unaware that a dangerous situation exists. Problems such as bad weather, information overload, instrument confusion, night flight, poor air traffic control communications, or malfunctioning ground navigational equipment all contribute to CFIT accidents. The purpose of this paper is to find whether flight instruments cause misinterpretations by the pilots leading to CFIT.

CFIT mishaps take place when a pilot is in control of the aircraft but unaware of the aircraft

altitude, surrounding terrain elevation, or the aircraft

position in terms of longitude and latitude. Without adequate warning of a problem, a pilot would be unaware that anything is wrong until it is too late. In past situations such as this, the ensuing crash is usually fatal. In a study done by Captain Dave Carbaugh of the Boeing Commercial Airplane Group titled "Avoiding-Controlled-Flight-Into-Terrain", he states "...that in the days of propeller driven commercial aircraft; CFIT caused over half of the aviation accidents recorded." (Carbaugh, 1997, pg 98) He also states that since the late 1950s, the beginning of the jet age, more than 9,000 fatalities have been attributed worldwide to commercial aircraft inadvertently hitting the ground. These statistics prove that CFIT has been one of the leading causes of aviation disasters throughout history.

Discussion

There are six primary errors that lead to CFIT accidents. A primary error is a mistake that is independent of any prior mistake. Poor communication, navigational mistakes, failing to follow procedures, a lack of situational awareness, improper systems operation, and poor tactical decisions all primarily contribute to CFIT. Some important contributing factors include:

* Communication: A flight-crew's inability to both give and receive information is critical to their ability to avoid danger. An incorrect read back of a radio frequency change or not hearing the correct frequency change could lead to confusion and lost communications with the Air Traffic Controller (ATC). Other communication factors that lead to problems are a flight-crew providing an inaccurate aircraft position to ATC or any other form of incorrect data. Any form of communication error can lead to confusion, thus opening the potential for a disaster to take place.

* Navigational: Selecting the wrong frequency for a radio navigational station, selecting the wrong radial or heading, or misreading navigational charts are navigational errors. An aircraft's flight-crew depends on instrumentation in order to fly at night or in instrument meteorological conditions (IMC). Any error that leads a flight crew away from their intended flight path poses danger. Since all of the tools used by a flight-crew require human input in order to work properly, the opportunity for error exists on every flight.

* Procedural: "As any of the main cognitive functions in a task could become so standardized that they are done automatically or unconsciously, this is the origin of so-called "shortcuts" in processing." (Bainbridge, 1999, pg 162) All human beings tend to take short cuts in order to make their tasks a little easier or even just to get the task completed a little faster. Pilots are human and often do not follow their cockpit procedures to the letter. Often, the short cut is simple and doesn't pose any threat to the safety of the flight. The short cut could possibly lead to an accident. The aviation community, airlines, regulatory agencies and aircraft manufacturers have prescribed a set of rules for each function of a flight-crew in given situations. These procedures or checklists are designed to ensure that all possible dangers are addressed by the flight-crew in a given situation making them aware of those dangers so they may avoid them. Shortcuts or omissions of these procedures may allow for a potential problem to go unnoticed resulting in the development of a dangerous situation that may jeopardize flight safety.

* Situational Awareness (SA): A flight-crew's loss of situational awareness is identified when a pilot controls an aircraft to the wrong parameters. Doane states that "SA has been highlighted in the aviation domain as an important precursor to performance failure." (Doane, Woo Sohn, Jodlowski, 2004, pg 92) An example of loss of SA is a flight-crew descending an aircraft below 3,000 feet prior to being established on the Localizer (an electronically provided extended runway centerline that allows pilots to use instruments to line up on the runway). These types of errors are extremely dangerous since aircraft may be close to terrain or obstacles and the flight-crew is generally unaware that a problem exists until it is too late.

* System Operation: Improper operation of engines, hydraulics, brakes and/or fuel systems; misread and improperly set instruments or disabled warning systems are all examples of improper system operation. Aircraft systems and instrumentation are vital to a pilot's ability to accurately fly the aircraft. The failure of a flight crew to use these systems correctly can lead to an inability to see and avoid potential dangers. Due to the complexity of most systems on aircraft the pilot can easily become overloaded with information relating to the aircraft

position in flight. "The pilot has gradually become barricaded from the reality of the flight task by an array of automated systems and is often swamped by the complexity of surrounding systems. Great effort has been made to control, filter and display the vast quantities of data related to the aircraft, its systems and the environment, at the same time as maintaining the 'visibility' of aircraft, system and environmental state." (Noyes, Kazem, Phyo, 2000, pg 679-680)

Ground Proximity Warning System (GPWS)

There are different systems used in the detection of terrain avoidance, one such system is the Ground Proximity Warning System (GPWS). In the mid-1970s, the introduction of the GPWS into aircraft belonging to major U.S. airlines significantly reduced CFIT accidents among large passenger carriers.