Belair A320 at Porto on Oct 1st 2013, intersection departure with full length power setting
Last Update: August 31, 2015 / 15:22:16 GMT/Zulu time
The French BEA reported in their weekly bulletin that the occurrence was rated a serious incident, Switzerland's SUST is investigating the occurrence.
On Aug 31st 2015 Switzerland's SUST released their final report conclulding the probable cause of the serious incident were:
The serious incident is attributable to the fact that the aircraft did not reach the necessary flight performance on takeoff, because the flight crew performed the takeoff from a runway intersection with an engine power which had been calculated for the entire length of the runway.
The following factors contributed to the serious incident:
- the fact that the commander was distracted by external circumstances during takeoff preparations;
- the uncomplete examination of the takeoff data within the frame of the "before start” checklist;
- procedures which stipulated individual checks only „if required”;
- the fact that essential checks were performed in silence.
The SUST reported that the captain (46, ATPL, 9,611 hours total, 1,624 hours on type) prepared the aircraft for a full length takeoff with reduced engine power, the relevant data were computed and entered into the flight guidance system. The crew subsequently briefed the takeoff, dueing the briefing it emerged that the takeoff mass was lower than initially anticipated and the captain decided to review an intersection F takeoff. The data for the intersection takeoff were computed and initially put on paper, the actual programming of the FMGS was postponed as the captain was distracted by a handling agent informing the crew of a missing passenger. The commander left the cockpit to take care of the matter and returned to the cockpit about 10 minutes later. ATC provided push back clearance and engine start clearance, the re-programming of the FMGS, that had been postponed earlier, did thus not happen. The first officer (33, ATPL, 2,185 hours total, 1,335 hours on type) was convinced the intersection takeoff data had been entered into the FMGS.
The crew requested an intersection F takeoff and when asked whether they were ready for an immediate takeoff (ahead of the preceding aircraft that was still taxiing for a full length takeoff) the crew accepted and was cleared for an immediate takeoff from intersection F.
The crew commenced takeoff, both pilots noticed the remaining runway was unusually short, however no power adjustments were made. V1 was reached 700 meters before the runway end, the aircraft became airborne 350 meters before the runway end and crossed the runway end at a radio altitude of 104 feet.
The flight crew discussed their observations but still did not recognize the error. Near the end of the flight duties the commander recognized the possible mistake, informed the first officer and the safety pilot. Based on the data it was then possible to confirm that the takeoff in Porto had been done with insufficient engine power.
The SUST analysed: "The procedures to be applied during cockpit preparation are designed to ensure that the takeoff data calculated on the EFB is consistent with both the takeoff data programmed on the FMGS and the intentions of both pilots. This was the case until the takeoff briefing for a full-length takeoff, during which the commander announced to the copilot the prospect of a change of his intention provided that the takeoff mass of 62.8 tons according to the load sheet would allow to do an intersection takeoff. In accordance with his declaration of intent, the commander calculated the necessary takeoff data for an intersection takeoff. The calculation confirmed that an intersection takeoff was possible with reduced engine power. After the commander and the copilot had agreed on an intersection takeoff and the copilot had checked the recalculation of the takeoff data, the copilot remained convinced until takeoff that the new calculated takeoff data were correctly inserted in the FMGS by the commander. The commander, however, remained certain that the reprogramming of the takeoff data was still pending when he was distracted by the handling agent because of a missing passenger. He therefore wrote the recalculated takeoff data on a piece of paper. The decision to interrupt his work and leave the cockpit at this stage was not appropriate to the situation and facilitated the occurrence of the present serious incident. By recording the intersection takeoff data on a piece of paper the commander broke his habit of programming the conservative case (in this case the intersection takeoff data) and recording the full-length takeoff data on a piece of paper. This made it possible after the distraction for the commander to regard the piece of paper as confirmation that the takeoff data for an intersection takeoff had been programmed in accordance with his usual habit."
The SUST further analysed: "Cockpit preparation must basically be in accordance with the QRH. It was done by the crew according to the procedures and completed with regard to a full length takeoff. Only afterwards the decision was made for an intersection takeoff and therefore uncomplete execution of the steps required by the cockpit preparation procedure remained undetected. The before pushback or start procedure again includes entering and checking the takeoff data, as well as working through a written checklist for the first time in the entire procedure. This checklist includes only seven points, one of which is checking the takeoff data (see Figure 17). In addition to the human factors mentioned in chapter 2.2.1, the following procedural factors may have contributed to the fact that even the use of this checklist did not lead to the discovery that the programmed takeoff data were incorrect: The formulations „TAKEOFF DATA...ENTER / REVISE” in the operating procedures and „TAKEOFF DATA...INSERTED” in the checklist do not explicitly include checking data which has already been entered. Obviousy only checks were made whether the takeoff data has been programmed and not which takeoff data has been programmed. The fact that entering and checking the takeoff data was subject to tasksharing between the PF and PNF and therefore varied from flight to flight. The taxi procedure includes the steps to be taken in the event that the takeoff data or the intended takeoff runway is changed (see Figure 19). As the copilot believed that the intersection takeoff data had already been programmed and the condition „if required” was therefore not fulfilled, he did not conduct these steps. The commander had no influence on this, because the copilot must complete the taxi procedure alone and in silence. The stipulation that the takeoff data check and takeoff briefing check should be performed in silence while taxiing is an inappropriately narrow interpretation of the sterile cockpit procedure. A „closed loop” between the pilots, which allows an incorrect assumption by one pilot to be identified and corrected by the other, is silent not possible. Furthermore, it remains unclear whether the check has taken place or has been forgotten."
This article is published under license from Avherald.com. © of text by Avherald.com.
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