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The human operator, the least reliable element of an aerodyne, but the most essential...!
Frank Caron (1991)


Last update:
26 September 2016

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Human Factors - B777 short runway take-off from intersection

Abbreviations

AAIB
B777
ECCAA
(UK) Aircraft Accident Investigation Branch
Boeing 777-200
(Antigua) Eastern Caribbean Civil Aviation Authority
TORA
N1
RWY
V1
Take-off Run Available
Engine power output
Runway
Take off decision speed

Objectives

The general goal is to have a look on this particular event from human factors point of view as a new approach to the mishap that happen in the industry.

Its single objective is to be educative. It does not intend to blame or even excuse, but providing another perspective.

It does not matter to be a pilot or not, flying with the concerned type of aircraft or not, because the focus is only the operator(s) behavior, with a different point of view: the way people act.

Summary of the event (from AAIB report)

Saint-Kitts ground chart

The crew received the aircraft's takeoff performance figures for a takeoff from intersection Alpha on RWY 07 at Robert L Bradshaw International Airport, St kitts, West Indies.

Having received taxi clearance to Intersection Alpha, the aircraft taxied to Intersection Bravo from where it subsequently took off; the crew believed they were at Intersection Alpha.

Intersection Bravo on RWY 07 is not an authorised takeoff intersection for the B777. The estimated TORA from Intersection Bravo was approximately 1220 m, which was 695 m less than the planned takeoff run from Intersection Alpha.


Technical analysis

The pilots of the twin-jet, bound for Antigua, had intended to depart from the southwestern end of RWY 07 - the 'A' intersection - at St Kitts' Bradshaw International Airport.

Despite specifically requesting a departure from 'A', the aircraft mistakenly taxied instead for the 'B' intersection, near the runway's midpoint, leaving available take-off distance of just 1,220m. The take-off performance calculations had been based on a distance of 1,915m.

The oversight escaped detection despite several references and queries in the communications between the crew and air traffic control.

In details of the event released today, the AAIB reveals that the carrier's station engineer and airport duty manager were on board the B777 and realised the error as the aircraft lined up on the runway.

The engineer quickly moved from his seat to speak to a member of the cabin crew, telling her that he needed to contact the pilots immediately to warn them the aircraft was wrongly positioned.

In the cockpit the captain had specifically commented that the runway looked short. Neither pilot had been to the airport before and the lack of a tractor meant the crew had taxied the jet from the stand themselves. But, in spite of the captain's concerns, neither cross-checked the jet's location on the runway.

Instead the captain told the co-pilot to "stand on the brakes", says the AAIB, and apply a high thrust setting - some 55% of N1 level - before releasing the brakes for the take-off roll.

In the cabin behind, the station engineer realised that the aircraft was powering up for take-off and abandoned his bid to reach the crew. The B777 accelerated but reached the touchdown-zone markers for the reverse-direction RWY 25 by the time it passed the crucial V1 decision speed, and lifted off about 300m from the end of the paved surface


Human factors analysis

Why had the pilots not reacted to the sight of the massive amount of runway on their left that was not available to them?

That is the question…

There is no (scientific) answer to this question. By scientific, It means an answer that can be repeated in a similar situation, which will give us the opportunity to train operators to avoid this bias.

There are very few things to understand about human behavior (named Human factors in this industry).

  1. You see, you hear and you feel what you expect to see to hear or feel. Definitely...,  but the roots of this bias are more deeper.

  2. Perception means collecting data from our external (or internal world) in order to use these data in our current behavior. If the perception is not in accordance with what we expect, we should be able to react to this discrepancy and adopt a new strategy. That seems logic!

  3. But this forgets that our perceptions are based and linked to our decisions. Here the decision was to join a runway through a taxiway and take off.

  4. We may have the illusion that decisions are real time process leading to actions. It may be. But in aviation were anticipation is one of the main factors that tailored the expert pilots, most of the decisions are taken well before the action. We call it “plan of action”, because if you want to perform smooth and efficient procedures, it is better to anticipate the upcoming procedures.

  5. So this crew (both of them), have made the decision to take off after joining the runway well before the time they reach this specific taxiway to line up on the runway. Since what you are doing seems in accordance with your plan (i.e. you expect to see a runway a front of your aircraft), it is very difficult to question the situation. I do not want to say it is impossible, but the fact is that is highly difficult…
    It does not matter you are an experienced pilot or not, you are just caught by what you have decided previously. Here, the captain has some concern, but because this, he will not reconsider his previous plan of action, and the FO won’t do it as well for the same reason, even though they both felt something was strange…
  1. This is one the bias we have to make operators aware (not only pilots), numerous errors are made early during a process (briefing, etc.). As a consequence, the erroneous result will be shifted in the future. The more time separating the decision and the action, the more it is difficult to reconsider the decision and its possible consequence(s).

  2. Yes, it is definitely a problem.
    But it has also one big and essential advantage for our daily behaviors… Just think differently… If we have to question systematically every decision we have made (previously or not), our life would be a… pure nightmare.
    Just imagine you permanently considering what has been done or not, properly or not, controlling every single action as it needed being always and always (re)evaluated.
    The consequence on our performance would be a disaster for 2 reasons:

    1. First, disturbing our behavior every minute if not seconds (just think about the number of decisions you take every minute…), will be a lost in efficiency, smoothness and result, therefore making us totally non-adapted to our operational needs.

    2. Secondly, we will be totally exhausted by the constant consumption of our mental resources used for this permanent questioning.

  3. Therefore this process (not reconsidering) is highly NECESSARY because it PROTECTS our daily behavior from permanent questioning and doubts.

We have to agree sometimes it would be useful to question, but most of the time it won’t be done…

But mental behavior does not always obey to scientific and logical...

The human behavior is hugely integrated and adapted to our world. Indeed, it is not perfect, and it appears full of necessaryparadoxes.

 

Frank Caron, September 2010.


quick links

5 steps to convince about safety

Why air safety improvement is too slow (organisation)?

Why air safety improvement is too slow (culture)?

Why training is the main solution to human factors issues

Human factors still the current challenge of the industry

No limits for the understanding of human factors

Suggestions for a discipline committee

Too long briefings

Current CRM have reach its limits

Aviation safety international legal definitions

Two statements about fatigue every manager must know