Severe wake turbulence. Just sit on your hands?
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Severe wake turbulence. Just sit on your hands?
The June 12-25 2017 issue of Aviation Week & Space Technology, published an interesting article called Wake Worries, by writer John Croft Washington.
It centred around wake turbulence from an A380 encountered by a Challenger 604 business jet over the Arabian Sea in early January 2017. The autopilot of the Challenger which had initially reacted to a roll to the right with left aileron input, disconnected when the business jet began rolling to the left.
The article states that when an encounter occurs, the pilots actions can help or hurt. Moreover, according to the FAAs wake-turbulence advisory circular, There is a history of wake- vortex encounter incidents in which pilot inputs exacerbated the unusual attitude situation caused by the encounter.
The agency notes that wake upsets may involve rapid roll reversals as the aircraft transitions across the wake and that pilots should avoid abrupt reversal of aileron and rudder control inputs. If altitude and conditions permit, it may be better to allow the aircraft to transition through the wake and then recover from any resultant unusual attitude, rather than aggressively trying to control the aircraft during the wake encounter says the FAA.
Flight data recorder information from the Challenger showed significant left aileron and left rudder input in response to the wake initially and following the autopilot disconnecting as well as significant right aileron application while left rudder remained. The investigation authority has not yet discussed whether these inputs were appropriate or whether the pilots had received upset recovery or wake-turbulence response training.
Finally, the article states an impending EASA safety bulletin is expected to instruct pilots to avoid rapid-roll control reversals and to avoid large rudder deflections.
..
I would hazard a guess that while upset recovery is part of most airline training syllabus, and in some States is an IPC test requirement, specific simulator training for wake turbulence events is probably quite rare. Some simulators have the ability to reproduce a wake turbulence event but mostly this involves nothing much more than benign rocking and rolling on final and easily countered by normal control inputs. In other words, a non-event.
Most modern simulators can reproduce jet upsets for example 130 degrees angle of bank and 25 degrees nose low. These are fixed numbers and the instructor may have to pre-set the attitude statically. Then when the simulator is unfrozen, pilots are taught to instantly apply full aileron to level the wings before applying G forces to recover to normal attitude. There are no rapid- roll control reversals or large rudder deflections involved.
Given this type of upset training can be quite different to wake-turbulence training (which seems to be non-existent at the moment), it is perhaps understandable that the Challenger crew were unaware that it may have been be better to allow their aircraft to transition through the wake of the A380 and then recover from the resultant unusual attitude. Easy to say now, but I wonder how many of us, like the Challenger crew, would have reacted instantaneously to that violent wake turbulence encounter rather than sit on our hands for a few interminable seconds and then recover from the resultant unusual attitude?
It centred around wake turbulence from an A380 encountered by a Challenger 604 business jet over the Arabian Sea in early January 2017. The autopilot of the Challenger which had initially reacted to a roll to the right with left aileron input, disconnected when the business jet began rolling to the left.
The article states that when an encounter occurs, the pilots actions can help or hurt. Moreover, according to the FAAs wake-turbulence advisory circular, There is a history of wake- vortex encounter incidents in which pilot inputs exacerbated the unusual attitude situation caused by the encounter.
The agency notes that wake upsets may involve rapid roll reversals as the aircraft transitions across the wake and that pilots should avoid abrupt reversal of aileron and rudder control inputs. If altitude and conditions permit, it may be better to allow the aircraft to transition through the wake and then recover from any resultant unusual attitude, rather than aggressively trying to control the aircraft during the wake encounter says the FAA.
Flight data recorder information from the Challenger showed significant left aileron and left rudder input in response to the wake initially and following the autopilot disconnecting as well as significant right aileron application while left rudder remained. The investigation authority has not yet discussed whether these inputs were appropriate or whether the pilots had received upset recovery or wake-turbulence response training.
Finally, the article states an impending EASA safety bulletin is expected to instruct pilots to avoid rapid-roll control reversals and to avoid large rudder deflections.
..
I would hazard a guess that while upset recovery is part of most airline training syllabus, and in some States is an IPC test requirement, specific simulator training for wake turbulence events is probably quite rare. Some simulators have the ability to reproduce a wake turbulence event but mostly this involves nothing much more than benign rocking and rolling on final and easily countered by normal control inputs. In other words, a non-event.
Most modern simulators can reproduce jet upsets for example 130 degrees angle of bank and 25 degrees nose low. These are fixed numbers and the instructor may have to pre-set the attitude statically. Then when the simulator is unfrozen, pilots are taught to instantly apply full aileron to level the wings before applying G forces to recover to normal attitude. There are no rapid- roll control reversals or large rudder deflections involved.
Given this type of upset training can be quite different to wake-turbulence training (which seems to be non-existent at the moment), it is perhaps understandable that the Challenger crew were unaware that it may have been be better to allow their aircraft to transition through the wake of the A380 and then recover from the resultant unusual attitude. Easy to say now, but I wonder how many of us, like the Challenger crew, would have reacted instantaneously to that violent wake turbulence encounter rather than sit on our hands for a few interminable seconds and then recover from the resultant unusual attitude?
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EASA Safety Bulletin published on wake turbulence. SIB 2017-10
https://news.aviation-safety.net/201...n-wake-vortex/
https://news.aviation-safety.net/201...n-wake-vortex/
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Riding out wake turbulence
Fascinating set of circumstances which will be concerning all Bizjet operators AND Flight Training departments.
http://aviationweek.com/business-avi...c93d7ea301d120
The impending EASA safety bulletin is expected to instruct pilots to avoid rapid-roll control reversals and to avoid large rudder deflections; I agree that this makes sense. However, suggesting that
"It may be better to allow the aircraft to transition through the wake and then recover from any resultant unusual attitude"
when crew will have been startled or frightened at the time, sounds like the same kind of safety committee 'ideal world' recommendation that has resulted in the Industry Standard Aeroplane Upset Prevention and Recovery Training Aid to develop FIVE distinct recovery strategies to deal with five distinct flight upset conditions; great in principle but almost certainly unworkable in practice.
http://aviationweek.com/business-avi...c93d7ea301d120
The impending EASA safety bulletin is expected to instruct pilots to avoid rapid-roll control reversals and to avoid large rudder deflections; I agree that this makes sense. However, suggesting that
"It may be better to allow the aircraft to transition through the wake and then recover from any resultant unusual attitude"
when crew will have been startled or frightened at the time, sounds like the same kind of safety committee 'ideal world' recommendation that has resulted in the Industry Standard Aeroplane Upset Prevention and Recovery Training Aid to develop FIVE distinct recovery strategies to deal with five distinct flight upset conditions; great in principle but almost certainly unworkable in practice.
Last edited by greeners; 5th Jul 2017 at 10:38. Reason: Insert article link
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Interim Report about the underlying incident
If you want more details about this incident, the German BFU has just published a preliminary report since the CL604 was registered in Germany.
