The Australian Transport Safety Bureau(ATSB) final report of Emirates EK407 tail strike has been released, pointing
towards human error in keying of wrong weight and speeds thereof, which resulted
in the aircraft failing to
accelerate correctly before over rotating close to the end of the runway and
striking the tail several times before becoming airborne and returning to land
safely. Although there were no injuries,there was damage to the aircraft
and to infrastructure at the Melbourne airport as the aircraft overran in march
2009.The aircraft A340-500, A6-ERG, was damaged as a result. An incorrect weight of 100 tones was keyed in.
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| Pic from ATSB Report |
In its report the ATSB said: "Previous investigations into similar data entry error and tail-strike occurrences have highlighted the inability of flight crew to conduct a 'rule of thumb' or reasonableness check of speeds when moving between aircraft types.”
"An unintended consequence of mixed fleet flying appears to be a reduction in a flight crew's ability to build a model in long-term memory to facilitate recognition of 'orders of magnitude', or a 'rule of thumb', in respect of take-off performance data."
Airbus has said that it plans additional
development to include functions checking that the aircraft has sufficient
runway length to conduct a safe take-off, the ATSB added.
In the history of aviation, there have been well over 20 such
incidents in the past 2 decades or so, involving the human errors in insertion,
computation and cross check of data amongst crew leading to such incidents.
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| Pic from ATSB report |
Will increased automation help in any way
to curb the errors of crew in containing this???
A valid viewpoint stems from FAA that such
systems, given “all of their inherent complexity”, would be “more problematical
than reliance on adequate airmanship”.
What is the way forward in addressing
these input and computation errors and
enhance safety??
Airmanship and Procedures
Crew workload is immense during pre-flight
when this activity of speed/weight computation takes place. Crew procedures by
way of cross checking the data for accuracy and computation, is essential, and
coupled with good habit forming and procedural compliance is the way forward.
For crew cross check to be effective, each
crew member shall calculate the speeds and thrust settings independently and
then cross check to see if there are any differences.
Standard Operating Procedures need to lay emphasis on the same.
Details from loadsheet need to be
independently noted by each crew, to avoid any consensus which could lead to an
error.
Fortifying crew procedures, cross check of
data derived, aircraft systems enhancement
to avoid wrong data insertion and increased thrust in training on this
front, will help enhance safety and avoid inevitable tail strikes.
Remember, a wrong keying of numbers on
your calculator, will not lead to safety implications, as opposed to wrong
keying of numbers on the flight management system.
Procedural Cross Check and Compliance, Effective Training and Pre-flight Time Management are the need of the hour.
Send in your views/comments
Its a double whammy when you input wrong lesser weight for calculation, as you derive lower speeds, use lesser thrust for takeoff, which is a perfect recipe for tail strike and a possible runway overrun.
ReplyDeleteGood old habit of cross check of data and speeds, adherence to procedures and conducting effective briefings go a long way to reduce the risk of accidents/incidents in operational environment.
Despite strict regulations and documentary support to operating crew to review the take off performance there are some hidden areas where dangers lurk within.
ReplyDeleteMany airlines adopt a standardized weight for passenger and cabin baggage. While some airlines advise the passengers to limit cabin baggage weight to seven kgs, enforcement is minimal and difficult. The check generally is at the check in stage and any baggage added after that especially duty free purchases are seldom accounted for. The premise is that statistical average should fall within the standardized weights. Most airlines in india adopt 75 kg as an adult weight with cabin baggage. Look around you the next time you are on a flight. Do the passengers and Their baggage seem within this norm ? How about the same on a predominantly holiday destination?
Take off performances are typically guided by One Engine inoperative scenario. Minor excesses in weights do not apparently affect a normal take off and the crew tends to overlook this infraction.
A ten kg increase in a 200 seat AC will result in a two ton unaccounted weights. When you are operating under critical weights this can have a significant impact not only during take off but in cruise as well. The excess weight reduces the safety margins and pushes the aircraft close to the coffins corner with reduced safety margins.