|Operator's Guide to Human Factors in Aviation
1 The Accident as a Situational example
As the accident involves two airplanes, it is necessary to look at it from the different perspectives of the flight crews:
1.1 Passenger Jet Crew’s Perspective:
Shortly after midnight, the chartered jet is about to leave the gate and taxi to the runway for takeoff. Weather conditions are good, with visibility above 10 km (6 mi) in light rain. Traffic is slightly higher than usual due to a football match. Work on several aprons and taxiways contributes to “light pollution” at night. You are the captain and the pilot flying. Radio communications are in French.
During the taxi checklist, you find a flag relating to the ram air temperature in the autothrust computer. Since it is authorized by the minimum equipment list (MEL), you begin taxiing toward the holding point. You need more time to assess the rest of the flight documentation concerning the problem.
What is your next move?
The first officer asks the tower controller for clearance to hold for a few minutes. The controller asks you to clear the taxiway leading to the runway threshold and to go to another holding position, and transfers you to the ground controller.
After going through the documentation, you request clearance to resume taxiing to the intended runway. After some exchanges with the ground controller, you are cleared to taxi and again transferred to the tower controller for takeoff. He clears you to line up at the runway threshold and hold, waiting for another airplane to clear the runway. You see some flashing lights to your left, which you attribute to roadwork and airplanes behind you. You are then cleared for takeoff. You hear radio transmissions in English.
Are you concerned that the radio transmissions are in English, since you are talking to the tower in French?
You assume that the transmissions are to and from the airplanes behind you.
The takeoff roll starts. When the first officer calls out “V1,” you glimpse the lights of another airplane 200-300 m (656-984 ft) ahead of you on the left, apparently waiting on a taxiway. Almost immediately, you realize the airplane is not holding; it is moving toward the runway.
What is your next move?
You prepare mentally to abort the takeoff and, before reaching VR, decide to abort, following your airline’s procedures.
You feel an impact behind the cockpit on the left that does not cause any trajectory change. Once the speed is under control, the first officer informs the controller you have just hit another airplane. The first officer repeats the message to the incredulous controller, giving further details of the airplane type and asking for an emergency service.
The airplane clears the runway.
What do you do now?
Upon confirmation by the chief flight attendant that there is no harm to the passengers, you decide not to evacuate and continue taxiing. The first officer goes into the cabin for a further check and reassures the worried passengers. The airplane is escorted to a holding position. Detecting a strong odor of fuel and suspecting a leak from the damaged left wing, you shut down the left engine to prevent any fire. Once the airplane has stopped, the passengers disembark quietly.
1.2 Turboprop Crew’s Perspective:
While the crew of the passenger jet is solving its MEL problem, the turboprop cargo airplane is leaving the ramp and taxiing to the runway threshold. Radio communication is in English.
The ground controller asks the cargo pilots if they are interested in taking off from a runway intersection since there is traffic ahead at the threshold and since the cargo airplane needs less takeoff distance. They say yes and are cleared to hold until another aircraft has landed.
The pilots hear radio transmissions in French, which they do not understand, and conclude that the transmissions do not concern them. They receive clearance to enter the runway and line up as number two. They start moving toward the runway while looking for the airplane that is number one.
They believe the number one airplane is the one they have just seen passing in front of them.
Would you be so sure?
The captain suddenly sees the lights from the passenger airplane coming at him from his right and brakes, but he cannot prevent the impact. The jet’s left wing tip strikes from the rear to the right, passing through the right propeller, the right door and smashes through the cockpit windows, killing the first officer and throwing him across the captain’s seat. The captain pushes away the body, tries to clear the runway and shuts down the engines. Seeing emergency vehicles coming toward him, he warns them about the still-rotating propellers with a red flashing light and then evacuates the airplane.
2 Data, Discussion and Human Factors
While taxiing, the captain of the passenger jet saw flashing lights to his left, which he attributed to roadwork and airplanes behind him. When he was cleared to take off, he heard some radio transmission in English that he attributed as to or from airplanes behind him. This information did not change his mental picture of the situation and did not modify his intentions.
When he eventually noticed the lights of the turboprop airplane ahead of him on his left, he perceived the airplane as being perpendicular to the runway, not moving and at a sufficient distance from the runway. He believed that the other airplane was holding and was on the ground controller’s frequency. The first officer was focused on the engine parameters and the airspeed indicator, and was holding the control column. He did not think the radio transmissions in English were of any concern.
From the other perspective, the turboprop captain was asked, while taxiing to the runway threshold, if he wanted to take off from an intersection taxiway. He was aware of the jet in front of him, holding for a reason that was unknown to him. He stopped his airplane at the indicated holding point on the taxiway and was transferred to the local controller. He heard some transmissions in French that he did not understand; the transmissions included the takeoff clearance for the passenger jet. Five seconds later, he was cleared to “line up and wait, number two.” The captain wondered who was number one for takeoff. He had just seen an airplane passing by on the runway. He had just transferred to a new radio frequency, so he was not aware that the airplane was landing, not taking off. However, interpreting it as “number one,” he entered the runway. Seeing the passing airplane slowing and exiting the runway, a doubt entered the captain‘s mind. He leaned to the right to look at the runway and suddenly saw the lights of the passenger jet that was starting to take off. He immediately braked but could not do much at that stage to avoid the impact.
Analysis of human factors can appropriately be applied to controllers as to flight crews. Direct vision of all ground traffic was nearly impossible for the tower controllers due to the light pollution on the taxiways. A possibility for the controllers is that, due to the runway work, all airplanes were expected to be taking off from the runway threshold.
3 Prevention Strategies and Lines of Defense
There are various strategies to prevent runway incursions. Due to the collaborative nature of aviation, they involve airlines, flight crews, air traffic control (ATC) service providers, controllers, airport authorities and regulatory agencies. Numerous automatic detection systems have also been proposed.
Procedures such as explicit ATC clearances for any airplane to cross any runway could be proposed. Policies to minimize or, when practical, eliminate the use of intersection departures could be worked out with ATC service providers. Standard taxi routes, common standards and recommended practices could be implemented.
Among human factors considerations, the possible influence of increasingly complex procedures and airport layouts on pilots and controllers in ground operations needs to be better understood.
The following are among primary factors in preventing errors caused by high workload, distraction and interruption, and visual illusion:
- Correct communication procedures and phraseology.
- Pre-planning and briefing intended taxi routes.
- Minimizing other flight deck tasks while taxiing.
- Situational awareness for surface movements.
Commercial, corporate and general aviation pilots should place particular emphasis on the meaning of signs and markings, land and hold short operations (LAHSO) instructions, taxi procedures, mandatory radio frequency procedures, International Civil Aviation Organization standard phraseology for airport surface movements and appropriate error reduction and correction strategies when uncertain of the airplane position or ATC clearance.
4 Key Points
- Always communicate clearly and use standard phraseology.
- Read back clearances with restrictions such as altitude, heading and runway number.
- Do not hesitate to request a clarification.
- Listen to the other traffic on your frequency, avoid idle chitchat.
- Keep a good lookout when the airplane is moving.
- Proceed with caution when approaching a taxiway or runway.
- Be ready when cleared for takeoff; do not move onto an active runway while trying to finish a checklist.
5 Associated OGHFA Material
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