April 13 2017 – GCAA publishes detailed investigation report on Sharjah incident 2015:
Airliner takes off from a Taxiway
United Arab Emirates General Civil Aviation Authority (GCAA) recently published a detailed investigation report that sheds light onto the following incident.
In the early morning hours of 24 September 2015 the International Airport of Sharjah in the United Arab Emirates only by coincidence escaped a major catastrophe. Despite the crew of Schaheen Air International flight 791 remaining unaware of their severe mistake, the consequences for the flight from Sharjah to Bacha Khan in Pakistan with 148 passengers and 5 crew members on board could easily have been devastating.
Although the event happened during night hours with usually a significantly lower traffic volume, the controller got into time pressure as he wanted to let the departing Shaheen Boeing 737-400 depart before an arriving flight. Possibly for this reason he did not question the recurring incorrect read back from the cockpit. A crucial misunderstanding which allowed a dangerous threat to persist.
“Without delay Cleared for Takeoff, Runway 30”
Due to the given time constraints – delay would have resulted in Shaheen flight 791 being forced to wait several minutes holding short of the runway – the controller issued a very early takeoff clearance and advised the crew to take off immediately. This pressure created an environment prone to error and – even worse – unmonitored by any safety net.
As a result of the rushed pre-departure phase with crew and controller believing to have successfully completed all necessary preparations for the departure, the crew takes one wrong turn, lining up the Boeing on the parallel taxiway instead of the runway. After advancing the thrust levers to takeoff thrust, accelerating and – from their perspective – lifting off uneventful from the airport the flight proceeds as planned to Bacha Khan in Pakistan. It takes several days until the investigation team informs the pilots of their mistake.
The controller on the other hand noticed the extremely dangerous happenings after the aircraft had accelerated some distance down the taxiway, but decided not to interfere with the rolling takeoff, since the affected taxiway was clear of traffic and he was unaware of the exact speed of the aircraft.
In a nutshell: Even though the prevailing conditions were not unusual and the controller was in full power of all his systems and capabilities, no safety net or procedure was capable of preventing an aircraft from taking off from a taxiway of a large airport. The occurrences of this night easily could have resulted in a horrific accident.
Airport-Lighting without Follow-The-Greens
TowerPad® and Follow the Greens – The Future of Airport Safety and Efficiency
Against the general perception incidents like the one in Sharjah occur repeatedly and often simple luck prevents the crash from actually happening.
To protect airports from such situations, ATRiCS has developed TowerPad®. This highly integrated controller working position provides the controller with an unrivalled intuitive tool to obtain highest situational awareness and effectively eliminate threats like the Sharjah example:
- “Follow the Greens” (FTG)
By switching on only those taxiway centerline lights which indicate the route for an individual aircraft, Follow the Greens is a technology greatly enhancing operational safety of aircraft on the airport. Pilots simply need to follow their individual route of green lights in order to safely arrive at their gate or departure runway. Taking a wrong turn, like Shaheen flight 791 did, is virtually impossible.
Furthermore Follow the Greens reduces the risk of misunderstandings about the taxi route which the controller experienced in the case presented. Taxi instructions are limited to a simple “Follow the Greens”, eliminating potentially wrong readbacks, reducing controller workload and relieving congested frequencies.
During extensive FTG trials at several major airports using TowerPad® ATRiCS was able to prove significantly reduced taxi interruptions and fuel burn. Both pilots and controllers confirmed the great relief in workload and enhancement of situational awareness.
- Routing and Guidance
The Routing and Guidance capabilities of TowerPad® allow the controller to easily assign, monitor and edit routes of an aircraft movement. Taking into account all relevant parameters such as weight and wingspan restrictions and flow patterns, TowerPad® calculates the most efficient route for every particular flight. Based on many different sensor sources the exact position of the aircraft is displayed on the screen at all times and gives the controller exceptional situational awareness – even during night or low visibility operations.
- Alerting Functions
If, for whatever reason, the pilot should deviate from the assigned route TowerPad® instantly triggers a visual and audible alert, effectively drawing the controller’s attention to the particular aircraft. In Sharjah this would have given the controller precious time for corrective actions, resolving the threat.
If the parallel taxiway had been on the route assigned to Shaheen flight 791, TowerPad® would have rapidly detected the excessive acceleration of the aircraft on the taxiway and warned the controller. During rejected takeoffs speed plays the most important role regarding possible end effects. An earlier warning can thus significantly decide on the final impact.
At ATRiCS, we work every day to further enhance safety in aviation in general and specifically in the most critical flight phases. Pushing the limits and changing the definition of safe airport operation is our prime and most important goal.
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