本研究將波音747型機之兩筆正常航班資料及一筆異常航班資料由飛行操作品質系統(Flight Operations Quality Assurance, FOQA)取出之飛行數據，利用小波法(Wavelet Transform)及希爾伯特-黃轉換(Hilbert-Huang Transform, HHT)加以分析。考慮許多相關程度高的參數，如空速、下降率、引擎推力、攻角、風速、風向等，從原始訊號分解出不同頻率之訊號，觀察訊號變化，研判出訊號有研究價值的部分，藉由兩個理論方法分析這些參數，比較三個航班之異常訊號。
本研究主要利用飛行力學以及推估導航之系統概念，藉由FOQA系統裡快速資料記錄器(Flight Data Recorder, FDR)所提供的降落飛行資料，重新建立二維平面風場。再將與降落有關的參數放進兩種理論方法加以分析。首先利用HHT解析訊號，HHT是一個優秀的工具，能闡述非線性和非平穩時間序列，產生不同頻率之訊號，與傳統方法相比，在隱藏物理現象的理解上，HHT具有更高頻譜的分辨率。HHT可將原始訊號將被分解出好幾個震盪模組(Intrinsic Mode Functions, IMF)，層層抽出，更重要的是了解分離後訊號背後代表之物理意義。其次有別於以往如傅立葉轉換(Fourier transform , FT)，短時快速傅立葉轉換(Short-time Fourier transform, STFT)等固定窗下的頻率解析，小波法(Wavelet transform)套用母小波來分析一段訊號。而不同高低之頻率需求不同長短的窗型來解析，因此小波法利用Morlet型母小波調整窗大小來達到解析高低頻率之間的缺點，因此解析度將比傳統方法得到在頻域上更突出的結果。
由相同數據產生HHT與小波法結果相互比較，藉以看出相同結果得以論證。綜合兩方法相輔相成訊號解說，得出更精準的分析結果，輔以飛安會報告，解讀出其中物理現象。重要的是，希望能藉由觀測分析參數中能"預測"某些尚未發生卻會對飛行安全造成嚴重威脅的不正常參數預警。

In this research, three flight data of Boeing747-400 including two normal and one abnormal are analyzed, which derived from Flight Operations Quality Assurance (FOQA), by using Wavelet Transform and Hilbert-Huang Transform methods. Considering the tremendous amount of relevant parameters involved, such as true airspeed, vertical speed, thrust, angle of attack, wind speed, wind direction, etc., we need to first decompose these engineering data to different frequencies inside the signals, observe their changes, and acquire valuable and meaningful flight interpretations. The main purpose for this work is to figure out unusual warning by contrasting with the analyses via two theoretical methods.
	In this study, we re-establish two-dimensional horizontal wind fields by data taken from Flight Data Recorder (FDR) via the equations of flight mechanics and the system of dead-reckoning. Then we could analyze parameters of wind speed and wind direction into HHT and Wavelet Transform formats.	HHT is a modern tool for non-linear and non-stationary time series interpretation, and has a high-resolution spectrum compared to traditional methods for understanding background physical meaning. In the cases studied, HHT gave results much sharper than those from any of the traditional analytical methods in the time-frequency-energy representations. Moreover, traditional methods such as Fourier transform (FT) and short-time fast Fourier (STFT), utilizing fixed window to analyze frequencies in signal, but Wavelet Transform applying a dilation window function to fit the length of the data, and it really work out on decomposing from high-frequency to low-frequency oscillation in signals. Therefore, Wavelet Transform obtains more prominent results in the frequency domain.
	 Data generated consequences of HHT and Wavelet method, compared with each other, in order to see clearly the results which were demonstrated. Comprehensive the interpretations of two methods combined with the report of Aviation Safety Council give us more precise analytical results in landing profile and physical phenomena. Moreover, our expectation is to obtain the "prediction warning message" which would pose a serious threat to flight safety before the occurrence of accident/incident from observing the abnormal parameters data set.

List of Contents
Abstract	i
List of Tables	vii
List of Figures	viii
Nomenclature	x
Chapter 1 Introduction	1
Chapter 2 Background Research and Literature Review	7
2.1 Accident Investigation Factual Data Collection Group 	Report	7
2.2 Aviation Occurrence Categories	8
2.3 Factors of Flight Safety	10
2.4 Stabilized Approach	14
2.5 Introduction to Flight Quality Operation Assurance (FOQA)	16
2.6 Introduction to Hilbert-Hung Transformation 	(HHT)	18
2.7 Introduction of Wavelet Transform	21
Chapter 3 Data Processing and Mathematical Method	28
3.1 Source and Types of Flight Data	28
3.2 Horizontal Wind Field	29
3.2.1 Estimate Sideslip Angle β	30
3.2.2 Estimate Angle of Attack α	36
3.3 Theoretical Method: Hilbert-Hung Transformation (HHT)	37
3.3.1 The Empirical Mode Decomposition (EMD)	37
3.3.2 Hilbert Spectral Analysis (HSA)	41
3.3.3 Completeness of Hilbert Transform	42
3.4 Theoretical Method: Wavelet transform	43
3.4.1 Morlet wavelet transform	43
3.4.2 Enhanced Morlet transform	46
3.4.3 Gabor transform	46
Chapter 4 Result and Discussion	57
4.1 Validation of Horizontal Wind Field	57
4.2 Parameters Analysis via Hilbert-Huang Transform and Wavelet Transformation	59
Chapter 5 Conclusion	78
References	85
Appendix A 	Equations of re-establishing wind field	89
Appendix B  Original FDR Readout Parameters (Engineering Data)	91
Appendix C	98
 
List of Tables
Table 2.1 Minimum stabilization heights	23
Table 2.2 Excessive flight-parameter-deviation callouts	23
Table 3.1 The specifications of overall airplane	47
Table 3.2 The parameters of FDR recorded	49
Table 4.1 Total time in landing	62
Table 5.1 Parameters of three specific time	80
 
List of Figures
Figure 2.1Aviation occurrence categories by Boeing	25
Figure 2.2 The rate of primary causes of accidents	25
Figure 2.3 Fatal Accidents and Onboard Fatalities by Phase of Flight 	26
Figure 2.4 The investigations of accidents and the statistical classification of the accidents causes of nationality civil air transport fixed-wing aircraft	26
Figure 2.5 The aiming point	27
Figure 2.6 The shape of a runway	27
Figure 3.1 Principal dimensions of B747-400	51
Figure 3.2 Principal dimensions of B747-400	52
Figure 3.3 Body station diagram	53
Figure 3.4 Body station diagram	53
Figure 3.5 Magnetic declination data by Nationnal Geophysical Data Center	54
Figure 3.6 Geometry of dead reckoning	55
Figure 3.7 The typical type of EMD procedure	55
Figure 3.8 The HSA procedure of HHT	56
Figure 4.1 (a) Wind speed determined by N3 with sideslip angle comparing with sideslip angle ignored (b) Factors of case N3 (c) Wind speed determined by N3 without singularity point	64
Figure 4.2 Wind speed determined by Event with sideslip angle comparing with sideslip angle ignored	64
Figure 4.3 Wind speed determined by Event with AOA 9 seconds damping and comparing sideslip angle with sideslip angle ignored	65
Figure 4.4 (a)Wind speed determined by Event with sideslip angle and compare AOA 4 seconds damping with 9 AOA seconds damping (b)Comparison of wind speed damping in 9 seconds or not	66
Figure 4.5 Wind speed below 50 feet of Event comparing with the AWOS	66
Figure 4.6 True airspeed analysis by HHT	67
Figure 4.7 Wind speed analysis by HHT	68
Figure 4.8 Wind speed analysis by Wavelet	69
Figure 4.9 Wind direction analysis of HHT	70
Figure 4.10 Wind direction analysis of Wavelet	71
Figure 4.11Lateral acceleration analysis by HHT	72
Figure 4.12 Lateral acceleration analysis by Wavelet	73
Figure 4.13 Radio height analysis via HHT	74
Figure 4.14 Radio height analysis via Wavelet	75
Figure 4.15 AOA analysis of HHT	76
Figure 4.16 AOA analysis by Wavelet	77
Figure 5.1 Comparison of on-board FMS wind, tower wind and actual wind encountered by an approaching aircraft	82
Figure 5.2 Rudder input analysis of HHT	83
Figure 5.3 Rudder input analysis by Wavelet	84

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