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Estimating Flight Characteristics of Anomalous Unidentified Aerial Vehicles in the 2004 Nimitz Encounter^{ †}

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## Abstract

**:**

## 1. Introduction

## 2. Nimitz Encounters (2004)

#### 2.1. Senior Chief Operations Specialist Kevin Day (RADAR)

#### 2.2. Commander David Fravor (PILOT)

#### 2.3. ATFLIR Video

## 3. Discussion

## 4. Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 1.**An analysis of Senior Chief Day’s radar observations. (

**A**) The posterior probability indicates the maximum likelihood estimate of the acceleration to be 5600$\begin{array}{c}+2270\\ -1190\end{array}$$\phantom{\rule{0.166667em}{0ex}}\mathrm{g}$. (

**B**) The accelerations obtained by sampling resulted in the most probable acceleration of 5370$\begin{array}{c}+1430\\ -820\end{array}$$\phantom{\rule{0.166667em}{0ex}}\mathrm{g}$ (red lines) while the mean acceleration is $5950\phantom{\rule{0.166667em}{0ex}}\mathrm{g}$ (black dotted line).

**Figure 2.**An analysis of CDR Fravor’s encounter based on a Truncated Gaussian distribution (${1/30}^{\circ}\pm {1/60}^{\circ}$) of Fravor’s visual acuity and a Truncated Gaussian distribution ($1\pm 1\phantom{\rule{0.166667em}{0ex}}\mathrm{s}$) of elapsed time. A. Gaussian distribution of distances based on the visual acuity distribution. B. The distribution of accelerations has a maximum at 150$\begin{array}{c}+140\\ -80\end{array}$$\phantom{\rule{0.166667em}{0ex}}\mathrm{g}$ (red lines) and a mean of $550\phantom{\rule{0.166667em}{0ex}}\mathrm{g}$ (black dotted line).

**Figure 3.**(

**A**) Frame 19 of the last 32 frames of the Nimitz ATFLIR video. The narrow horizontal and vertical lines intersecting at the right edge of the UAP image indicate the position of the UAP. (

**B**) The pixel intensities along a row of the frame are plotted along with the best Gaussian curve fit. The rightmost edge of the craft is defined as the center position of the Gaussian plus one standard deviation (indicated by the vertical red line). (

**C**) This is an illustration the data (+), the most probable kinematic fit (solid curves) to the UAV positions in the Nimitz ATFLIR video, and the residuals (model minus data) for the model described by (11). Details can be found in Table 1.

**Table 1.**Kinematic Models for the Nimitz Video Given the log evidence (logZ), Model 4 (

**bold**) is most probable with a net acceleration of $75.9\pm 0.2\phantom{\rule{0.166667em}{0ex}}\mathrm{g}$.

Model | logZ | LogL | ${\mathit{a}}_{\mathit{x}}\left(\phantom{\rule{0.166667em}{0ex}}\mathbf{g}\right)$ | ${\mathit{a}}_{\mathit{z}}\left(\phantom{\rule{0.166667em}{0ex}}\mathbf{g}\right)$ | ${\mathit{x}}_{\mathit{o}}\left(\phantom{\rule{0.166667em}{0ex}}\mathbf{m}\right)$ | ${\mathit{z}}_{\mathit{o}}\left(\phantom{\rule{0.166667em}{0ex}}\mathbf{m}\right)$ |
---|---|---|---|---|---|---|

Model 1 | $-253,640$ | $-253,614$ | $-71.1\pm 0.7$ | – | $-15.40\pm 0.04$ | $119,700\pm 1200$ |

Model 2 | $-236,950$ | $-236,287$ | $7.564\pm 0.002$ | $99.994\pm 0.005$ | $-13.36\pm 0.04$ | $12,193\pm 1$ |

Model 3 | $-53,282$ | $-53,261$ | $-40.2\pm 3.8$ | – | $-4.02\pm 0.05$ | $49,700\pm 4800$ |

Model 4 | $-\mathbf{52},\mathbf{084}$ | $-\mathbf{52},\mathbf{031}$ | $-\mathbf{35}.\mathbf{64}\pm \mathbf{0}.\mathbf{08}$ | $\mathbf{67}.\mathbf{04}\pm \mathbf{0}.\mathbf{18}$ | $-\mathbf{3}.\mathbf{89}\pm \mathbf{0}.\mathbf{05}$ | $\mathbf{43},\mathbf{870}\pm \mathbf{110}$ |

**Table 2.**Summary of Estimated Accelerations ranging from about $75\phantom{\rule{0.166667em}{0ex}}\mathrm{g}$ to over $5300\phantom{\rule{0.166667em}{0ex}}\mathrm{g}$. Detection Modalities refer to Multiple Pilots Visual Contact (Vs), Radar (R), Infrared Video (IR).

Case | Detection Modalities | Kinematic Model | Figure | Min. Acceleration |
---|---|---|---|---|

Day | R | (1) | Figure 1B | 5370$\begin{array}{c}+1430\\ -820\end{array}$$\phantom{\rule{0.166667em}{0ex}}\mathrm{g}$ |

Fravor | R,Vs | (7) | Figure 2C | 150$\begin{array}{c}+140\\ -80\end{array}$$\phantom{\rule{0.166667em}{0ex}}\mathrm{g}$ |

ATFLIR | R,Vs,IR | (11) | Figure 3C | $75.9\pm 0.2\phantom{\rule{0.166667em}{0ex}}\mathrm{g}$ |

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**MDPI and ACS Style**

Knuth, K.H.; Powell, R.M.; Reali, a.P.A.
Estimating Flight Characteristics of Anomalous Unidentified Aerial Vehicles in the 2004 Nimitz Encounter. *Proceedings* **2019**, *33*, 26.
https://doi.org/10.3390/proceedings2019033026

**AMA Style**

Knuth KH, Powell RM, Reali aPA.
Estimating Flight Characteristics of Anomalous Unidentified Aerial Vehicles in the 2004 Nimitz Encounter. *Proceedings*. 2019; 33(1):26.
https://doi.org/10.3390/proceedings2019033026

**Chicago/Turabian Style**

Knuth, Kevin H., Robert M. Powell, and and Peter A. Reali.
2019. "Estimating Flight Characteristics of Anomalous Unidentified Aerial Vehicles in the 2004 Nimitz Encounter" *Proceedings* 33, no. 1: 26.
https://doi.org/10.3390/proceedings2019033026