本來昨天應該發出來的，但是忘了在原創上面打鉤，由於擔心有些同行不自覺，因此只能刪除今天重新發了。
經過這麼長時間的初步調查，NTSB發布了一份關於科比座駕墜毀的初步調查報告。
這份報告裡面信息量還是挺大的，大家要是閒著沒事可以一起來看看。
先附上這份報告的PDF網頁連結，有興趣的可以去下載。
https://int.nyt.com/data/documenthelper/6771-ntsb-report-kobe-bryant-helicopter/aaacf7d3b80c17083a22/optimized/full.pdf#page=1
原文就不附上了，下文中會以節選的方式呈現。
同時，為了讓人更好的理解這個報告，我也從油管上扒下了一個視頻，講解者是美國著名資深網紅飛行員Juan Browne（下文簡稱胡安）。
在視頻裡，胡安強調了幾個比較值得注意的要點，我們可以來一一看一下。
在視頻一開始，胡安就講述了一下NTSB的步驟，主要分成三個部分，包括了：我們現在所看到的初步調查，公布所有機械數據的過渡期調查，和12-18個月後的最終調查報告。
同時胡安也強調了這次調查的重要性，這次調查的結果可能會直接導致美國135部針對包機，尤其是直升機包機的規則改革和重建，以加強135部的安全性。
All significant components of the helicopter were located within the wreckage area. Examination of the main and tail rotor assemblies found damage consistent with powered rotation at the time of impact. The initial point of impact consisted of highly fragmented cabin and cockpit debris. The vertical pylon and horizontal stabilizer were located about 40 feet below (downhill from) the impact crater. A witness mark consistent with the length and width of a rotor blade and containing fragments of rotorblade skin and honeycomb was positioned perpendicular to the direction of the debris line and directly above the impact crater. One piece of 2-inch diameter tree branch was cut cleanly in 3 locations (similar to saw cuts) about 30 feet prior to the initial impact crater. Approximately 95 % of the main rotor blades were recovered. All four blades exhibited similar damage consisting of midspan bending, pocket separation, blade tip separation, and leading-edge indentations and scuffing.
根據現場的勘查，從主旋翼和尾部旋翼等主要部位的碎片以及周圍被切斷的樹木都能夠看出，飛機在墜毀之前兩個旋翼都還在正常轉動，換一句好理解的話說，那就是槳葉損壞的方向一致，說明是發動機在運轉時觸地，導致槳葉被打折，如果是停轉之後摔下來，那麼槳葉的部分應該是不一致的。
用一張類似的圖片來表示的話，大概就是這個樣子。
且，根據發動機的主要殘骸來看，也沒有發現明顯的故障痕跡。
所以根據初步的排查，可以初步排除掉飛機發動機在空中停車之後墜毀的可能性。
ATC communications and radar data indicate the flight departed KSNA about 0906 PST. N72EX proceeded to the north-northwest at an altitude of about 700 to 800 feet mean sea level(msl） under under visual flightrules (VFR ). At 0920, as the aircraft neared the Burbank class C airspace, the pilot requested to transition the area along Highway 101. The current Burbank weather observation reported instrument flight rules (IFR) conditions. In response to the pilot s request, the air traffic controller advised that cloud tops were reported at 2,400 feet msl and queried the pilot s intentions; the pilot then requested a special VFR clearance ( an ATC authorization to proceed in controlled airspace at less than VFR weather minima). The air traffic controller advised that the pilot would need to hold for a short time due to IFR traffic , which the pilot acknowledged. At 0932, ATC cleared the pilot of N72EX to transition the class C surface area following the 5 freeway , maintaining special VFR conditions at or below 2,500 feet. The pilot acknowledged with a correct readback and climbed to approximately 1,400 feet msl (600 feet agl). In response to query, the pilot replied to the Burbank ATC that he would follow Highway 118 and 「loop around VNY [Van Nuys Airport] follow Highway 101. ATC acknowledged and coordinated .
The pilot reported to SCT that the flightwas going to Camarillo at 1,500 feet. The SCT controller advised that he would not be able to maintain radar contact at that altitude and terminated services. The SCT controller was subsequently relieved by a different controller. At 0945, the pilot of N72EX again contacted SCT and advised he was climbing above cloud layers and requested advisory services. The second controller was not aware of the aircraft, as services had previously been terminated, so asked the pilot to identify the flight. The SCT controller then asked the pilot his intentions, to which he replied he was climbing to 4,000 feet. There were no further transmissions.
請注意報告中的紅字部分，我們從這兩段可以看出來，當時Burbank的天氣報告中提到，雲頂高為2400英尺，在無線電中斷之前，飛行員表示會爬升到4000英尺。
而飛行員實際上爬升了多高呢？
我們來看ADS-B的數據。
Radar/ADS-B data indicate the aircraft was climbing along a course aligned with Highway 101 just east of the Las Virgenes exit. Between Las Virgenes and Lost Hills Road, the aircraft reached 2,300 feet msl (approximately 1,500 feet above the highway, which lies below the surrounding terrain) and began a left turn. Eight seconds later, the aircraft began descending and the left turn continued . The descent rate increased to over 4,000 feet per minute (fpm), ground speed reached 160 knots. The last ADS-B target was received at 1,200 feet msl approximately 400 feet southwest of the accident site .
簡單翻譯一下，飛機爬升到了2300英尺，8秒之後開始下降並且左轉，下降率接近4000英尺/分鐘，地速達到了160節，ADS-B最後的信號顯示飛機高度為1200英尺，水平距離殘骸發現地約400英尺。
雲頂高2400英尺，飛機最高爬升到了2300英尺，就差100英尺飛機就可以出雲恢復到完全目視的狀態，就差100英尺。
這100英尺決定了這架飛機的命運。
視頻講解者胡安認為最後的這個左轉代表著飛行員當時已經失去了對飛機的控制，這就解釋了飛機為什麼好好的沿著101高速爬升，卻突然開始莫名的左轉與快速下降，以及左轉的坡度越來越大。
同時，這組數據也推翻了之前「飛行員下降尋找著陸點」的推測，畢竟當時飛行員已經通知了ATC自己要爬升，可以視作一個逃逸動作。按照胡安的說法，這個動作叫做Emergency IMC Maneuver，翻譯過來就是緊急儀表氣象條件機動。
那為啥一個已經開始機動的飛機會突然左轉並且極速下降呢？
目擊者也證實飛機有一個左轉的趨勢。
The witness stated that the area was surrounded by mist. Hesaid he began to hear the sound of a helicopter, which hedescribed as appropriate for a helicopter flying while in a powered condition . He perceived the sound getting louder and saw a blue and white helicopter emerge from the clouds passing from left to right directly to his left. He judged it to bemoving fast , travelling on a forward and descending trajectory . It started to roll to the left such that he caught a glimpse of its belly. He observed it for 1to 2 seconds, before it impacted terrain about 50 feet below his position .
The helicopter was not equipped with a flight data recorder or cockpit voice recorder (CVR) nor was it required to be for the accident flight. The helicopter was equipped with a four-axis automatic flight control system , electronic flight instrument system, radio altimeter, and ADS-B transponder . It was also equipped with a flight management system (FMS). The airworthiness group retained the FMS computer to examine it for any available recorded data stored in memory, and also retained two flight control computers, four gyros, and the standby attitude indicator for further examination. A number of personal electronic devices were recovered from the wreckage and will be examined for any relevant data.
現在所知，飛機上沒有黑匣子，飛機裝備有四軸自動操縱系統，電子儀表系統，無線電高度表，和ADS-B。同時飛機上還有飛行管理系統。
飛行管理系統的電腦已經回收，並且從現場收集了所有機上人員的個人電子設備（手機，EFB）調取事故相關的數據。
按照胡安的解釋，飛機裝備有四軸自動操縱系統，這就意味著飛機是有自動駕駛的，但是當時並不符合使用自動駕駛的條件，因此可以認定當時飛機是進行人工飛行的。NTSB回收了所有系統的電腦部分，試圖找出相關數據，是為了確定飛機的操縱系統在當時是否出現了故障。
這裡值得一提的是上文紅字部分的無線電高度表，無線電高度表的作用是給出一個飛機和地面的垂直距離，其工作原理和聲吶相似，都是通過計算回波反射的時間來確定垂直距離的。大概原理用圖來表示。
換句話說，只要無線電高度表正常工作，那麼飛行員是隨時可以知道自己和自己正下方地面的相對距離的，很多飛機（我不知道這架S-76有沒有）的無線電高度表在探測到異常的接近率之後還會發出近地警告，防止可控撞地發生。
且，根據機務維護記錄顯示，飛機有4716.1小時的飛行時間，飛機沒有明顯的故障或者保留。這一部分內容就不做單獨的解讀了。
The pilot,age 50, had worked for Island Express for about 10 years. According to FAA records, the pilot held an FAA commercial certificate with ratings for helicopterand instrument helicopter, as well as an FAA instructor certificate for flight, instrument,and ground instruction. His most recent FAA second-class medical certificate was issuedon July 3, 2019, with a limitation stating, 「must have glasses for near vision.」 At the time of his last medical application, he reported 8,200 total hours of flight experience. The pilot logged about 1,250 total hours in the S76 helicopter.His most recent flight review, including proficiency trainingin inadvert ententry into instrument meteorological conditions(IIMC) and unusual attitude recovery, was conducted in a helicopter with EUROSAFETY International on May 8, 2019.The pilot received satisfactory grades for these maneuvers.
從資歷上看機長也算是個老資格（胡安甚至認為他是公司的總飛行師），已經為當事公司Island Express(下文簡稱IEH)工作了10年，持有FAA的商照+直升機儀表籤注，並且還有FAA的飛行教員和地面教員的執照。
機長使用的是在有效期的二類體檢合格證，但是因為近視所以需要配鏡飛行，在上一次體檢時，他申報的總飛行小時數為8200小時，其中在S76機型上的時間是1250小時。
最重要的是，在上次的熟練檢查中，機長已經在飛機上完成了進入儀表氣象條件和非正常姿態改出的訓練並且檢查合格，檢查員的評語為「滿意」。
而進入儀表條件和非正常姿態改出，正是這次事故中被重點調查的內容。
Island Express Helicopter sheld an FAA Part 135 operating certificate, number 29EA847N, for on-demand VFR-only operations, since 1998 and conducted offshore oil industry support flights and charter flights.The company’s operations specifications document listed six helicopters including the accident aircraft:1 SK-76A,2 SK-76B,2 AS-350-B2 and 1 AS-350-BA. Some charter flights were coordinated through a third-party broker, OC Helicopters, Santa Ana, California. At the time of the accident, Island Express Helicopter shad 25 employees, including 6 pilots.
IEH是一個135部的公務機公司，公司擁有6架直升機以及包括6名飛行員在內的25名員工。
值得注意的是他們的直升機業務要求只能進行目視飛行業務，而出事時的氣象條件很難稱得上完全滿足目視飛行要求。
雖然初步的調查報告發布了，但是由於沒有黑匣子數據的支持，整個過程依舊疑點重重，我們很難確定這到底是機械故障還是人為因素造成的慘劇。
如果是機械故障，飛機的動力系統是好的，而且飛機上有無線電高度表直觀的提醒飛機與地面的相對距離，那或許就只能從飛機的操縱系統或者其他什麼系統上找原因，是否是因為機械故障而導致了飛機最後的不正常下降與偏轉。
如果是人為因素，那這次事件中最大可能的誘因只有：進入儀表氣象條件與不正常姿態。但是機長在最近的熟練檢查中都以「滿意」的程度完成了這兩個科目，作為一名經驗豐富的飛行員，不應該出現無法處置的情況。
無論如何，最令人惋惜的是，飛機只差100英尺就可以出雲，如果起因不是機械故障的話，對於飛機的性能來講，這100英尺僅僅需要再多個幾秒，或許整個結局就會變成一次機長在喝咖啡時跟人聊天談起的有驚無險的談資。
這一切的答案，只能期待NTSB最終的調查報告，甚至，這起空難會成為一個永恆的迷。