Hazard criteria for wake vortex encounters during approach

Luckner, Robert; Höhne, Gordon; Fuhrmann, Michael

doi:10.1016/j.ast.2004.06.008

Cited by 44 publications

(29 citation statements)

References 12 publications

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“…In these scenarios, the heave axis perturbations feature heavily. Consequently, a measure or criteria based on flightpath may be a helpful adjunct in assessing severity; for fixed-wing wake encounters, steps have been made in this area [13] and this method could be adapted for rotorcraft.…”

Section: Discussionmentioning

confidence: 99%

“…Ref. [13] proposes that these encounters are known as 'navigate' go-arounds because the pilot is uncertain of position, or has lost the instrument tracking task, or it would be dangerous to attempt to re-acquire the flightpath. The alternative is an 'aviate' go-around where the go-around is initiated immediately because the disturbance is excessive.…”

Section: Vortex Severity Criteria Developmentmentioning

confidence: 99%

“…This is likely to be because the heights used in these experiments are above a threshold where the attitude vs. severity relationship is fairly constant. Other criteria such as the NASA roll attitude criteria in [13] have a single boundary for acceptable roll disturbance that reduces with reduced height. It is expected that such a relationship will also exist for rotorcraft at lower heights but with the incorporation of multi-axis disturbances.…”

Section: Vortex Severity Criteria Developmentmentioning

confidence: 99%

“…For example, Ref. [13] has assessed and developed criteria based on the roll attitude disturbance or the ratio of available control power to the roll disturbance induced by the vortex. Via these analyses the authors were able to achieve good levels of prediction for encounters that resulted in go-arounds.…”

Section: Vortex Severity Criteria Developmentmentioning

confidence: 99%

See 3 more Smart Citations

Wake vortex encounter severity for rotorcraft in final approach

Lawrence¹,

Padfield²

2008

Aerospace Science and Technology

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Section: Discussionmentioning

confidence: 99%

Section: Vortex Severity Criteria Developmentmentioning

confidence: 99%

Section: Vortex Severity Criteria Developmentmentioning

confidence: 99%

Section: Vortex Severity Criteria Developmentmentioning

confidence: 99%

See 2 more Smart Citations

Wake vortex encounter severity for rotorcraft in final approach

Lawrence¹,

Padfield²

2008

Aerospace Science and Technology

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“…V to assess the quality of the VSM in comparison to the LES based simulation. Roll axis upsets and disturbances of the aircraft's vertical motion (e.g., changes in vertical speed and glide path deviations) are important parameters for the pilot's hazard assessment of a wake encounter during landing [17]. For example, the vortex-induced rolling moment coefficient was used as hazard metric to justify the separation scheme that was proposed by the International Re-Categorization Team for RECAT Phase 1 [18].…”

mentioning

confidence: 99%

Simulation Methods for Aircraft Encounters with Deformed Wake Vortices

Bieniek¹,

Luckner²,

Visscher³

et al. 2016

Journal of Aircraft

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Simulation of aircraft wake-vortex encounters is regularly applied in the research toward revised aircraft separation minima. Most encounter flight simulation studies have used a pair of straight counter-rotating vortices. However, after being shed by the generating aircraft, the wake vortices begin to develop a growing deformation due to the long-wave Crow instability, especially under low-turbulent atmospheric conditions when vortices decay slowly. In this study, two methods for simulation of aircraft encounters with such perturbed wake vortices are described and compared. The first method uses a vortex simulation model, which is based on analytical models of the deformation that consider the large-scale vortex shapes. The second method applies vortex-velocity fields from high-fidelity largeeddy simulations. It offers the highest possible level of realism and is used as the reference. The resulting aircraft responses induced by wavy vortices and vortex rings are reproduced with good quality by the vortex simulation model. The comparison of both methods shows that the vortex simulation model captures the overall impact of vortex deformation on the aircraft upsets. It can be used for future safety assessments that require a large number of encounter simulations.

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Verification of Eventual Consensus in Synod Using a Failure-Aware Actor Model

Paul

Agha

Patterson

et al. 2021

Lecture Notes in Computer Science

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Successfully attaining consensus in the absence of a centralized coordinator is a fundamental problem in distributed multi-agent systems. We analyze progress in the Synod consensus protocol-which does not assume a unique leader-under the assumptions of asynchronous communication and potential agent failures. We identify a set of sufficient conditions under which it is possible to guarantee that a set of agents will eventually attain consensus. First, a subset of the agents must behave correctly and not permanently fail until consensus is reached, and second, at least one proposal must be eventually uninterrupted by higher-numbered proposals. To formally reason about agent failures, we introduce a failure-aware actor model (FAM). Using FAM, we model the identified conditions and provide a formal proof of eventual progress in Synod. Our proof has been mechanically verified using the Athena proof assistant and, to the best of our knowledge, it is the first machine-checked proof of eventual progress in Synod.

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Hazard criteria for wake vortex encounters during approach

Cited by 44 publications

References 12 publications

Wake vortex encounter severity for rotorcraft in final approach

Wake vortex encounter severity for rotorcraft in final approach

Simulation Methods for Aircraft Encounters with Deformed Wake Vortices

Verification of Eventual Consensus in Synod Using a Failure-Aware Actor Model

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