DALLAS – Photos of the grounded Korean Air (KE) Airbus A330 after the recent runway overrun at Cebu (CEB) raise the obvious question: “What went wrong?”
Accidents are rarely the result of a single cause, and there are often multiple links in the chain of events that all conspire to lead to the unfortunate event. A common analogy that aviators often use has to do with the holes in many layers of cheese, all stacked at the same time.
As investigators sift through the various streams of data recorded by the plane, vital clues must be uncovered. The cockpit voice recorder records what the crew was thinking and planning at the time. In contrast, the data recorder provides highly detailed reproduction of a wide range of aircraft parameters.
In addition to these recorders located near the tail of the aircraft, multiple channels of engine and system data are often transmitted to airlines and engine manufacturers.
Combining all of this data will allow incident investigators to build a clear picture of the most dominant factors that contributed to the incident.
Overrun the track
Track excursions continue to be a significant threat to the industry. Given that an aircraft landing maneuver is still performed manually except in extremely poor visibility, human vulnerability continues to be challenged.
My recent article on how pilots calculate landing performance mentioned how the industry has worked hard in recent years to emphasize the importance of advance planning rather than simply relying on “this usually works at this airport”.
Before landing, pilots can always perform a go-around, which is when the approach is aborted and the climb is done away from the runway. Also known as a missed approach or overshoot. This alternate maneuver is still available in many aircraft until reverse thrust after touchdown is selected. You could be forgiven for thinking that taking off after the landing gear has already touched the runway is unusual.
On the other hand, consider if it’s a choice between climbing far from the runway or landing at an incorrect speed and/or position. Come to think of it, maybe it’s not such a strange concept after all, and it’s what’s called a failed landing.
According to flight tracking data, the KE crew made two go-around attempts before the third approach that led to the accident. So the crew successfully executed two missed approaches and apparently weren’t afraid to go around when previously necessary.
Weather reports on the day of the accident painted a stormy picture with cumulus clouds reported to be close to CEB at the time. These clouds can pose a major threat to aircraft because they are associated with the formation of thunder and lightning.
In addition, they are often located near areas of heavy rain and gusty and unpredictable winds. Pilots must adhere to strict airspeed tolerances during final approach. In more unstable conditions, such winds can make it almost impossible to maintain airspeed within the permitted limits.
Practice makes perfect
In practice, go-around flights are rarely performed, but they almost always occur at some point in periodic simulator training. Even if the act of flying a missed approach is a byproduct of another rehearsed maneuver.
Despite this regular training, there are still an inconvenient number of approaches continuing until landing, when a go-around would be a safer option. Factors such as landing at a familiar airport or crew fatigue can sometimes contribute to pilots continuing to land in inappropriate situations.
Another factor that can influence the pilot’s decision is the amount of fuel remaining. In good weather, some airlines allow their crews to carry less or no diversion fuel, or for that fuel to be expended in flight if necessary, provided the probability of landing at the destination is very high.
Given the bad weather around CEB at the time, the crew in this situation should have planned to have enough fuel to divert to another airport. However, some crews still feel under pressure when the runway is so close after descending to a very low altitude on the approach, and the diversion alternative looks very unattractive in comparison.
Flight crews are well-acquainted with working in a controlled environment where strict procedures and strict legislation work together to provide crews with a clear framework of what is safe and permissible and what is not. Despite the fact that this framework is binary in that compliance is either achieved or not, we still see situations where suboptimal decisions are made in the cockpit, contributing to landings that occur when it would be safer to are not made.
When an approach does not meet the prescribed tolerances for the descent profile and aircraft configuration, the industry classifies it as “unstable”. Not surprisingly, the number of unstable approaches can be measured in percentage points.
What may surprise you is that of the small number of unstable approaches, the vast majority continue to land rather than opting for the safer go-around option. Figuring out why this happens brings us to a much more complex but fascinating topic.
A number of airlines, and more recently the business aviation sector, have recognized in recent years that understanding the science behind pilot psychology and decision-making is at the root of many approach and landing incidents.
Presage Group is a Canadian firm that identifies and implements solutions to reduce human error in process-driven workplaces. The firm’s work is so highly regarded that airlines often benefit from insurance cost savings as a result of Presage Group delving into the inner workings and culture of an airline and then offering bespoke solutions to reduce operational risk.
Such studies are broad in scope and results are often wide-ranging.
In addition to improving safety and adherence to procedures during the approach and landing phases, significantly increased efficiency can often be found in other phases of flight. One example is that wheel brake component change intervals can be extended as pilots take a more structured and methodical approach to power management.
A culture clash
This article would be incomplete if we did not discuss the impact that culture can have on the effectiveness of how a team of pilots work together. While the captain is legally responsible for the safe conduct of the flight, the vulnerability of the human being requires a constant stream of cross-checking and monitoring by both pilots, regardless of their experience.
However, in some countries, co-pilots who speak up when something goes wrong are considered disrespectful to their older colleague.
Of course, whether such a factor played a role in this incident remains to be seen, but respecting cultural niceties at the expense of flight safety is a trait that the National Transportation Safety Board (NTSB) has identified as a significant factor in the tragic crash of KE801 on approach to Guam (GUM) in 1997.
Amidst the grim headlines that report yet another plane crash, sometimes there is still a silver lining to be found. These are the lessons that can be shared and learned to make the industry safer for all of us.
The size of the silver lining, of course, is determined by the thoroughness and transparency of the subsequent accident investigation.
Featured Image: Overview of Salt Lake City (SLC) Airport with snow. Photo: Michael Rodeback/Airways