以下是波音对2009年7月22-23 日在北京举办的民航现代化论坛相关问题的答复
2009年7月22日上午的小组提问：
1. 主题：ADS-B. （1）ADS-B报文有效性，由长短报文的不连续性而造成的问题。（2）ADS-B数据包的安全性问题。（3）GPS信号干扰ADS-B安全性问题是使用这项技术的国家应当解决的重要问题。
上述ADS-B问题是政策性问题，应当由使用ADS-B技术的国家解决。
2. 主题：AOD 什么是“集成数据链”
集成数据链是指航空器通讯管理单元（CMU）与飞行管理系统（FMS）之间传输数据的能力。这将使直接装载航空器飞行计划变更至FMS变为可能，而且机组可以在导航显示看到这个航行计划变更；如果这个变更是可接受的，机组可以通过按一下键进行执行。
3. 主题：AOD “未来数据链监视”包含那些具体内容？
空中交通系统路线图中的未来数据链监视和未来通讯能力指的是未来的更高级的空地通讯能力，这一能力目前还没有被定义。可以想见，在未来这项能力将被运用于监视数据，指令，气象数据以及其他任何驾驶舱需要的数据。
4. 主题：以飞机为中心的新技术先进进场管理
(1)新技术能够在多大程度上降低着陆标准（能见度/云底高）
着陆最低标准由若干因素的组合决定，这其中包括但不仅限于垂直导航所使用的传感器的性能。最低决断高度通常由机场周边或者复飞段的地形和障碍物决定。RNP进近使用气压高度量度提供垂直导航（也被称为baro-VNAV）。baro-VNAV进近目前可以被授权使用最低250英尺的决断高度。使用GBAS或ILS支持有自动着陆的自动进近。可以达到的最低决断高度由许多因素决定，包括机场灯光，进近和复飞段的地形和障碍物，以及导航传感器的误差特性。（例如用于提供导航的传感器的精度和完整性）。ILS当前可以支持0决断高度和跑道视程300英尺的进近。GLS（基于GBAS）支持与ILS基本相同的进近。但是，最初的系统是按照支持一类盲降的标准设计的（例如，决断高200英尺，跑道视程半英里）。相应的运行经验可能允许这些系统最终被用于支持更低的决断标准。一个对GBAS标准的升级正在进行，以使其足以支持三类b仪表最低标准运行（例如，0决断高，跑道视程300）。
(2) GLS的关键技术是什么？有什么问题可能会限制GLS的应用？
GLS是指飞机的一项功能，这项功能使用地基增强系统提供引导。GBAS是一个本地GNSS差分系统，包含一套安装在已知地点的经过测量的参照接收器，处理计算机和一台VHF数据广播无线电装置以及天线。其关键技术是参照台站使用基本GPS接收机，并使用多径限制天线。另外，地面站数据处理结构的设计必须包含用以支持高完整性运行的冗余机制。
(3) 有什么问题可能会限制GLS的应用？
GBAS的开发已经有超过15年的历史。误差源和失效模式已经被分析清楚，并且针对各个威胁的监控系统也已经开发完成。对于短基线差分系统最麻烦的误差源是非差分可校正误差，此误差由异常电离层状态造成。在强烈太阳风暴发生时，相对小尺度的电离层结构可能导致误差的产生，这个误差无法通过地面站修正和完整性信息充分地补偿。这个问题是导致推迟引入使用GBAS支持的一类盲降的运行的主要因素。减轻这类误差的方法已经开发完成并且已植入地面站，FAA将在近期对此进行批准。
其他可能限制GLS应用的问题包括RF频率干扰，或VDB数据链的VHF频率可用性。在一些地区，由于108-118兆赫频段拥挤，因此很难为GBAS站分配频率。我们不认为中国在未来会碰到这个问题。
5. 进场管理。NextGen的研发活动与欧洲SESAR的区别是什么？
在SESAR和NextGen的路径和概念中对于先进进场管理这部分还处于发展阶段。两者都包括使用基于低RNP等级的RNAV，VNAV以及在航路和进场环境中使用要求到达时间（RTA）运行。其他可能用于进场范围的技术以及这些技术在进场过渡和终端区域内的空地一体化应用是两个计划将要开发的项目。如想了解更多关于NextGen的信息请浏览http://www.jpdo.gov/library.asp , SESAR相关信息可参见http://www.sesarju.eu/public/standard_page/library_list.html .
6. 主题：AOD。如何处理在路线图，导航和监视领域的传统设备是一个非常重要的决定。请介绍美国业界（包括FAA,航空公司，制造商）处理这个问题的策略。
描述美国业界策略是很难的事，因为美国航空业包含许多利益相关方，他们有着不同的目标和限制。波音的观点大体是--当一项新技术已被确定提供足够显著的收益（安全，容量和效率）来保障一项投资时，各方应加速进行这项投资，并且一起协作来尽快改变空域的运行。 此外，当新的能力和运行程序在一个特定的空域占主要地位时，各方应享受成本削减的收益，这一收益可以通过退役那些不再需要的设备来实现，同时避免对额外的过时的能力进行投资。这些是波音认为保持集体化系统经济可行性所需要的指导方针。
7. 主题：AOD. 我同意近期收益很重要的观点。当我们谈到“近期”，我们无法避免谈到如何解决拥有新能力的飞机和不具有新能力的飞机在一个空域运行的问题。波音对此有什么建议？
“近期”总是指一种情况，在这种情况下需要对空域进行设计，使其可以满足新旧能力的同时运行。这意味着多种方法，从分隔交通流到允许动态地混合交通流。为装备或未装备的飞机保留一条专用的跑道是一个分隔交通流的例子，保留时段可以是一天的某个时段或者是整天，此外也可以根据装载设备状况限制空域的使用。动态混合意味着跑道和空域同时地接纳新旧装备，这同时也意味ATC程序和自动工具系统的设计必须满足安全，容量和效率的要求。每一个机场和空域的选择将很大程度上由新装备的装备情况和政策导向决定。
8. TA与CDA. TA与CDA的主要区别是什么？
连续下降进近
和与最优下降剖面(OPD)本质上定义了在所有给定的空域和运行限制下的最受益的下降剖面。3D轨迹进近管理(3D PAM) 和定制进场 (TA)定义了在特定技术环境下实现CDAs/OPDs的运行联系：从下降顶点到终端机动区入口或跑道入口的CDA/OPD，语音或数据链运行，有/无地面自动系统支持的运行，等等。末端状态定制进场提供有地面自动系统支持下的数据链解决方案，此方案涵盖从TOD到跑道入口的航段。
9. CMM航空系统的管理，推广和实施。CMM航空系统的现代化落后于国家现代化发展的要求。我们要不要考虑在运行批准中加入新技术？这将对安全和正点运行有好处。没有要求就不会开始实施。
这个评论很难理解。根据我们的理解，是这是一条建议而非提问。这条评论说道民航系统现代化应当集成到国家现代化计划中。航空公司应当是国家现代化计划的一份子，这将加快计划的实施。
2009年7月22日下午的小组提问
10. 主题：ADS-B. 要使ADS-B覆盖中国大陆区域需要多少个地面站？那么总投资将是多少？澳大利亚的情况是什么样子？
地面站的需求将决定于中国特定的ADS-B实施计划。例如：无雷达覆盖区域的ADS-B Out应用有可能首先着眼于中国西部。雷达已覆盖的东部沿海地区可能不需要立即配备ADS-B Out的能力。
11. 主题：ADS-B实施。为什么ADS-B Out要在ADS-B In之前实施？为什么不同时实施？
在特殊情形下ADS-B-In可以与ADS-B-Out同时实施， 例如在青藏高原。大多数的区域一般先实施ADS-B-Out来建立最低的机载装备（应答机和GPS），进以开发使用ADS-B的运行程序，并逐渐取得管制员/飞行员的接纳。ADS-B-In需要对机载设备进行大量投资（驾驶舱显示设备），如果能够取得直接运行收益，那么也是值得投资的。
12. 是否由政府牵头实施PBN新技术，还是由航空公司自行决定实施？
民航局飞标司已领导此项工作
13. 主题：CDA。如果中国实施CDA/TA，需要做什么样的工作？例如：飞机改装，地面设施建设？
CDA的实施将由目标空域所预期需要支持的交通量水平决定。这将定义通讯，地面自动化和航电系统的技术要求。在相关的区域实现CDA至少需要地面自动系统能够通过使用工具，例如航路下降咨询，来提供基于时刻的计量和轨迹生成功能。末端状态定制进场将需要有上述能力的地面自动系统，空中和地面系统的数据链能力，另外航空器至少有RNAV和VNAV能力。但是，非数据链支持的解决方案，例如使用动态轨迹生成地面自动系统的3D航径进场管理（3D PAM）或使用静态航路结构（例如，预先定义飞行路径）的3D航径进场管理解决方案也是可行的，并提供早期的收益。
14. 主题：ADS-B。波音演讲中提到“采用UAT是做1090ES的备份。”但是有来自FAA的声音显示UAT在GA中被采用并被保留，用来提供免费的METO和航行信息。请证实。
UAT被FAA采纳，但不是出于技术原因。双系统将导致延迟，从而损害系统的运行性能。
15. 主题：ADS-B地面空中监视技术。ADS-B Out信号从发射机到接收机按视距传播。请解释这是什么意思。
视距传播的定义是在发射天线（例如，飞机发射机）和接收天线（例如，地面站天线）之间不受阻挡的一条路径。由于地形可能在低高度阻挡地面站信号，这对ADS-B Out的性能将产生不利影响。
16. 主题：先进进场管理。高流量进港运行中的RNP应用。从适航的角度，FMS与数据链如何工作？我们是否需要对地面电子设备进行和航空适航类似的工作？如果是，怎样做？
集成数据链对于RNP全飞行阶段运行将是一个推动因素，集成数据链可以直接将上传数据输入到飞行管理计算机(FMS),而不需要飞行员手动输入。美国FAR25飞机认证中包括了对FMS/数据链功能的认证。因此，所有具有集成数据链的被交付飞机都具有数据链功能和集成FMS/数据链适航性。
FAA121部的授权将许可在特定的运行环境中使用特定的飞机设备和能力。在这个过程中，航空公司需要展示机组在特定的运行环境中如何使用飞机和相应运行能力，以及航空公司拥有相应的机组程序去飞行飞机和相应的能力。航空公司还要展示拥有执行非正常程序的能力以及适当的以完成正常和非正常程序为目的训练。这不只局限于FMS和数据链。
地面自动化系统的认证是空中交通服务提供者（ATSP）的责任，但要求涵盖航空公司运行中心自动化系统和飞机系统的适当部分。先进进场管理的评估受安全管理评估程序指配，这需要考虑运行中每一部分的责任，能力和性能。这一程序一般始于详细的系统需求和目标描述(SR&O)。SR&O详细描述了功能和系统需求，提出潜在的运行问题和缓解方案。这有助于建立运行框架，包括航空器运行程序和地面系统/ATM/AOC界面。贯穿整个地面自动化系统开发的详细的检验和验证程序保证了系统，界面和运行都达到预期。ATSP可能需要其他的程序用以管理和检验程序数据和飞行信息。程序的具体内容和相关的授权受到法规或者已取得的运行批准支配。
17. 主题：ADS-B. 我们知道，新技术将在未来二十年被应用，并且超过50%的飞机应当装备ADS-B。也许实际效能需要在未来的使用中用更长的时间来评估。
新技术的运行能力必需包含于投资决策之前的成本收益分析之中。如果不存在运行收益，那么充分的设备装载水平就不会达到，因此ADS-B In的程序应当被开发出来。假定ADS-B In运行会产生显著的用户收益，这将证明飞机设备的花费成本是值当的。任何程序开发的延迟将造成装备的延迟，进而延后用户收益。
18. 主题：ADS-B的安全问题。任何人都能够接收ADS-B信号会不会成为一种威胁？对保障商业飞行的安全有什么建议？
ADS-B安保是一个重要的问题，实施ADS-B的国家必须处置这个问题。这是一个政策性的问题。
19. 主题：ADS-B。能不能讲一下UAT和VO2-4技术和实施？
在ADS-B演讲中已经阐明，波音推荐并支持单一的1090拓展间歇震荡器系统。
2009年7月23日的小组提问
20. 主题：SWIM。什么是SWIM发展的主要障碍？
SMIW发展的主要障碍包括组织，文化，标准发展和基础设施。管理系统范围的信息需要改变组织编成方式。另外，当每个人希望得到所有可用的信息并且都赞同分享信息是一个普惠的行动时，让组织放弃信息是很难的事情。创建一个建立信息分享的共同语言的标准需要很多的时间和行动，因为现在对于计算机信息有许多不同的看法。这就如同创建一个有着共同语音的语言一样困难。各地的基础设施不必完全相同，但是限制其多样性对于建立协作能力是有利的。
21. SWIM: 当前实施SWIM的最大挑战是什么？安保？或者是投资？有没有新的规则将要被加到系统之中以管理SWIM?
最大的挑战是改变组织文化，参见上文第24条。
安保是一个需要下功夫的要点，但是现在已经有了建立信息安全所需的标准和技术。处理投资问题的最好方法是将SWIM应用到它被设计使用的新系统中。
改装花费虽然较高但是可以节省维护成本，从而证明是值得的投资。管理 SWIM的最好办法是建立具有管理整个信息系统权限的首席信息官。
22. SWIM: 请给出对于“服务”和“SOA”的明确定义和功能应用与“服务”的区别。NextGen SWIM 与 SESAR SWIM有何区别？
信息服务指的是使用计算机和通信网络的集合传递信息。这与近30年来发展的大多数计算机系统的模式不同。它们是基于软件作为处理数据的应用的想法建立的。通过个体的界面来完成需求是系统之间少许的联系。信息服务一般使用几个计算机和应用来收集，处理和传递信息。想象一下气象服务之于气象预报应用。SOA(服务指向构架)以服务的集合开始，建立计算机应用程序和网络以收集，处理和传递这些服务需要的信息。网络被许多服务共享，而不是按照个体的目标设计。在一个或两个应用之间进行共享是昂贵的，但是在多服务之间进行共享是经济的。
NextGen SWIM 和 SESAR SWIM的概念是一样的。SESAR 和 NextGen 正在共同开发AIXM (XML航空信息)和XML气象。对于共享交通活动信息还有很多工作要做，此项工作正在协作进行中。
23. 数据连。什么样的数据链新技术可以进行应用？
欧洲空管和FAA正在为2011至2017时间段于欧洲和美国实施基于ATN的VLD 模式2 的ATS国内运行而进行工作。欧洲空管已经发布了一个数据链的强制规定，预计FAA也将在近期发布。由此，数据链解决方案将可能于这个时间段内在波音和空中客车飞机上可用。其他数据链技术可能被开发和提议，但是不大可能在这个时段内被空中交通服务提供单位接受。
24. 能否介绍一下ICAO在ADS-B运行、发展和应用方面的政策及标准？
ICAO的ATM要求计划正在考虑监视问题并在评估备选方案，但目前还没有明确的要求。波音将继续监控ICAO的相关进展。
25. ADS-B: ADS-B信息可以通过卫星数据链发送和接收吗? 飞跨太平洋航线的飞机不能与地面站联系，可以采用ADS-B作为地面监视吗?
不可以， ADS-B Out只能在1090 MHz上传输。 ADS-B In的应用比如正在实验中的未来空中导航系统 (FANS) ADS-B-寻址是使用卫星数据链的，可以用于洋区空域。
26. GNSS: 核心星座?
“核心星座” 是指组成自主卫星导航系统的系列卫星。比如，GPS就是一个核心星座。一个SBAS卫星不能被认为是一个核心星座，因为用户不能仅使用SBAS卫星就可以确定他/她的位置。增强通常是相对于一个或多个核心星座提供的服务或信号完成的。
27. GNSS: 请介绍一下ARAIM和RRAIM概念。
RAIM表示接收机自主完好性监测。RAIM算法是一种方法，可使GPS接收机探测和缓解由于卫星或核心星座系统其他部件失效而导致不可接受的位置误差过大。基本概念就是，为确定一个四维位置，需要4个测量值（即伪距测量）。如果5个以上的测量值可用，系统变成“过度定位”（即信息多于确定4个未知数所需要的）。如果系统过度定位了，所有可用的测量值都会被用来计算4个未知数，得出“最适”的可用数据。如果一个测量值存在重大失效，那么数据就会不一致。RAIM算法估算最适数据的不一致性，并用它来指示潜在的失效条件。
ARAIM表示绝对RAIM。这是目前RAIM算法最常使用的类型。ARAIM算法将每套测量值作为独立的一套数值并估算适用数据的不一致性，而不去管任何历史测量值和先前的系统状态。这种算法有时称为“快照”算法。
RRAIM表示相对RAIM。在这类RAIM算法中使用了误差源特性的一些知识以及有关系统状态的一些历史信息来改进错误探测和/或隔离能力。该算法通常仅利用载波相位观测值来及时预测前向位置。因为载波噪声很小，误差阀值可以设置得更为严格。在整周模糊度估计中，任何大的慢偏移值都可以预计。利用基于载波的RAIM算法，可以快速探测到高动态误差更高的动态误。象误差这类的更大的偏移值可利用噪声的时间平均方法以及总误差估计来发现。这可能包括一些系统（比如SBAS）的外部监测，可以探测或减轻大的、缓慢发展的偏移，但可能会有不可接受的长时间才能发出警告。RRAIM 总体来说不是“快照”算法，它是有一定“记忆”的。外部监测、警告时间和关于误差特性动态的假设之间达成一种此消彼长的平衡。
28. GNSS:
(1) 你如何看在美国使用CATI GBAS?
美国目前在两个地点部署了GBAS: 田纳西州孟菲斯和新泽西州纽瓦克。但是，美国以外的其他国家一直以来对GBAS更感兴趣。更有意思的应用实际上在其他地方正在进行（比如澳大利亚悉尼，德国不来梅）。
(2) 能否介绍一些美国一类/二类航电和地面系统发展路线图的信息?
一家公司（柯林斯）已研发出了具有GBAS能力的航电设备，第二家公司（霍尼韦尔）也快完成研发。这些航电设备基于RTCA DO-253B标准，通常被称为"CAT I" GBAS设备。然而，有可能这些航电设备的使用将不限于CAT I 进近最低标准（比如200英尺 DH 和 ½ 海里 RVR）。有可能CAT II进近最低标准将最终获得运行批准。这些批准可能依赖HUD或自动驾驶运行与所谓“CAT I”GBAS系统一起使用。（这与今天允许使用“设备一类”ILS地面站支持CAT II运行最低标准是一样的。）
Eurocontrol 就第一代GBAS用于低于CAT I最低标准的运行发起了一场业界与局方的讨论。在美国，FAA目前没有正式的计划用联邦政府的资金购买GBAS来支持CAT I运行。美国目前正在进行的项目都是“非联邦”项目，主要是业界提供资金。FAA参与并支持了由航空公司主导的应用，并作为具有CAT IIIb能力GBAS地面站的最终采购项目减小风险举措的一部分。
过去几年中ICAO一直在制定新一代GBAS的标准，目前已接近完成。第二代GBAS将可以向后兼容第一代，但预留了其它服务类型，旨在支持失效可工作的着陆运行（比如CAT IIIb条件下的进近着陆）。预计2014年之前将完成基于这种研发的先期运行批准。多快能成型取决于需求。一些由航空公司、服务提供商和局方组成的团队必须共同开展“概念验证”项目。这种验证项目应随着用于CAT IIIb运行的GLS获得最初运行批准而告终。这样的项目能产生GLS CAT IIIb运行所需要的相关适航和运行批准标准。
29. GNSS:
(1) GLS如何引导飞机到下滑道?与 ILS有什么不同?
以从RNAV到GLS过渡的角度来说，它与ILS是一样的。 FMS飞RNAV程序，航道 (LOC) 和下滑道 (GS) 方式是 "预位的"。当飞机到达与基准航道（中心线或下滑道）一定的距离之内，自动驾驶自动通过截获机动过渡到LOC或GS方式。这与ILS的工作是完全一样的。但是，由于GLS引导信号在有限覆盖时更为清晰的特性，它的截获性能比ILS有所提高。
(2) GLS的优缺点是什么?
GLS的优点:
- 一个地面站可以服务一个机场的所有跑道端，可以是同一跑道端的多个进近（比如，位移的跑道入口，多条下滑道等等）。
- 不用保护关键和敏感区 – (可导致高跑道利用率)。
- 卓越的性能 (更清晰的信号，没有波束弯曲)。
- 减少飞行校验。
- 在终端区可提供更高的精度和完好性以支持RNP应用。
GLS的缺点:
- GLS是一个新的系统，所以配备要花费时间。有些设施可能需要在很长的一段过渡时期保留ILS。
- 新的系统将需要新的飞行校验装置。但是，定期飞行校验的要求减少或消除了。
30. GNSS: 请描述一下如何协调与标准化GPS高度和气压高度。（飞机需要气压高度，GNSS提供实际的物理高度。）
目前的GPS传感器输出相对于平均海平面 (MSL)的高度。(这是通过使用地球水准面模型完成的，GPS使用椭圆体作为基准面。) 气压修正后，气压高度也生成相对于MSL的高度。但是，即使用同样的坐标系表达，GNSS高度和气压高度也不能互换。出于多种原因，气压高度将很可能继续作为运行使用的主要高度信息源。目前的所有情况下，GNSS垂直定位只有当跑道坐标系的基准正确时才可以使用。(比如 LPV 或 GLS 运行)。 FAA即将发布有关驾驶舱里正确使用和显示GNSS高度信息的咨询通告。(AC 20-163)
31. GNSS: 美国的GPS可靠吗? GPS由美国军方控制。听说由于资金不足美国的GPS可能在明年崩溃。
GPS一直以来被证明是相当可靠的。波音预计它将继续保持可靠。但是，近期美国审计总署（GAO）的一项研究引发了媒体上的大量争论，该分析称星座的健康状况可能在未来几年（从明年开始）出现退化。GAO报告中的分析有些悲观，因为它没有考虑美国国防部（DoD）可用的一些风险规避的备选方案，比如动力管理以及让仍然在轨但“停用”的“备用”卫星重新服务的可能性。尽管如此，目前的计划中几乎没有余地，所以任何卫星发射的延迟可能会影响到星座的健康。GPS星座从来没有像现在这么大（32颗运行卫星以及可以重新被启用的几颗在轨“停用”的卫星）。此外，该星座的平均年龄也从来没有像现在这么大。波音正在研究并将密切关注此情况的发展。
美国国防部已公开宣布其将继续运行GPS的意图，让我们能享有像几年前一样的高标准。国防部也承认我们所看到的高度冗余的星座（比如30多颗卫星而不是标准的24颗卫星）有着不能继续维护的风险。每个使用GPS的单位应该认识到这样的风险并做出相应计划。例如，所有使用GPS的运行都应该做出一旦GPS不可用该怎么办的应急预案。除了非故意RF干扰也还会有其他原因使失去GPS称为可能。因此，做出备用运行程序或减轻非计划服务中断的预案是十分必要的。
如果GPS星座的健康性有所减弱，不太可能出现突然“崩溃”的情况，更可能发生的情况是逐渐退化。比如，服务中断的时段可能会逐渐变得频繁和更长。作为缓解轻这种现象的手段，大量使用它的用户应考虑利用增强功能来减轻服务可用性不可接受的可能。比如，在容量提升很关键的高价值机场，RNP的可用性可以通过安装支持GBAS定位服务（GBAS/PS）的GBAS来保护。在SBAS服务可用的国家可以使用SBAS。
32. GNSS: LAAS基准接收机的精度与地点和数量有关吗?一个机场需要多少接收机?如何确定需要多少个?
GBAS地面站的精度部分取决于基准接收机的个数。由于微分修正是通过所有基准接收机的测量值平均完成的，测量噪声得到了平均。但是，这还不是包括多个基准接收机的主要原因。主要原因是允许对测量值进行交叉检查以探测个别基准接收机的失效或单一基准接收机里有多个通道。总之，冗余度越大，监控能力越强。此外，使用多于要求的最低数量的基准接收机可使得系统成为“失效可工作”。比如，如果一个地面站一般用3个基准接收机能产生足够的精度和完好性，那么有4个基准接收机同时工作可使运行对一个基准接收机失效不敏感。
Boeing Subject Matter Expert Responses to Panel Questions from the Civil Aviation System Modernization Symposium held in Beijing, China on July 22-23, 2009
Panel Questions from July 22, 2009 morning:
1. Topic: ADS-B. (1) ADS-B message validity, problem caused by incontinuity of long message and short message. (2) Security issue concern of ADS-B data package. (3) Issue of interference GPS signal ADS-B security is an important issue that must be addressed by the states implementing ADS-B.
The above ADS-B issues are matters of policy and must be addressed by the states implementing ADS-B.
2. Topic: AOD. What is “integrated datalink” in details?
Integrated datalink refers to the capability of transferring data between the Communication Management Unit (CMU) and the Flight Management System (FMS) in the aircraft. This enables the direct loading of changes to an aircraft’s flight plan into the FMS, and the crew can view on the navigation display and execute with one keystroke if acceptable. This is a key enabler for “trajectory based operations,” where the FMS and ATM ground automation systems directly exchange trajectory data while minimizing crew and ATC workload.
3. Topic: AOD. What is the detailed contents of “Future Datalink surveillance?”
Future Datalink Surveillance and Future Communication Capability on the Air Transportation System Roadmap refer to a future higher performance air-ground communication capability that is yet to be defined. It is conceivable that this future capability could be used for surveillance data, clearances, weather data, and any other data needed in the flight deck in the far-term.
4. Topic: Airplane Centric New Technology Advanced Arrival Management.
(1) How much improvement does new technology provide to lower the landing minimums (VIS/ceiling)?
Landing minimums are determined by a combination of factors including, but not limited to, the performance of the sensors and systems used in vertical guidance. Minimum decision heights are often determined by obstacles and terrain in the airport environment or on the missed approach. RNP approaches use barometric altitude measurements to provide vertical guidance (also known as baro-VNAV). Baro-VNAV approaches today may be authorized with decision heights as low as 250ft HAT. With GBAS or ILS automatic approaches with automatic landing are supported. The minimum decision altitudes achievable are again a function of many factors including airport lighting, obstacles and terrain on the approach or the missed approach and the navigation sensor error characteristics (i.e. accuracy and integrity of the sensor used to produce guidance). ILS can currently support approaches with no decision height and Runway Visual Range of 300 ft. GLS (based on GBAS) supports operations that are essentially identical to ILS operations. However, the first generation of the system was developed based on requirements that were intended to support approaches to CAT I minimums (i.e. 200 ft DH and RVR of ½ mile). Operational experience may allow these systems to eventually be used for lower minimums. An update to the standards for GBAS is currently being developed to enable a new type of service that should be sufficient to support CAT IIIb operations to the lowest minimums (i.e. no DH and RVR 300).
(2) What are the key technologies of GLS system? What are the problems that may restrain GLS application?
GLS refers to an airplane function that uses a Ground Based Augmentation System (GBAS) to provide guidance. GBAS is a local differential GNSS system comprised of a set of surveyed reference receivers at known locations, processing computers and a VHF Data Broadcast radio and antenna. The key technologies are the basic GNSS receivers used in the reference stations, and multi-path limiting antennas. Also, the ground station processing must be designed with an architecture that facilitates redundancy for high integrity operations.
(3) What are the problems that may restrain GLS application?
GBAS has been in development for 15+ years. The error sources and failure modes are well understood and monitoring schemes for each of the associated threats have been developed. One of the most problematic error sources for the short baseline differential system has been non-differentially correctable errors induced by anomalous ionospheric conditions. During severe solar storms, it is possible for relatively small scale structures in the ionosphere to introduce errors that will not be adequately compensated for by the ground station corrections and integrity information. This problem has been a significant contributor to the delay of the introduction of GBAS to support CAT I operations. Means of mitigating these types of errors have been developed and incorporated into the ground station which should imminently be approved by the FAA.
Other problems that could restrain a GLS application might be RF frequency interference, or availability of VHF frequencies for the VDB datalink. In some areas of the world, congestion of the 108-118 MHz band will make it difficult to assign frequencies for many GBAS stations. We would not anticipate this being a problem within China.
5. Arrival Management. What’s the difference between NextGen Research activities and European SESAR research activities?
Many of the SESAR and NextGen approaches and concepts for advanced arrival management are still in the development phase. Common to both are the use of RNAV with low-level RNP, VNAV as well as the use of Required Time of Arrival (RTA) en-route and in the arrival domain. Possible additional technologies for use in the arrival domain and the operational use of these technologies along with the air-ground integration in the arrival transition and terminal area are still forthcoming in both programs. For more information on NextGen please refer to http://www.jpdo.gov/library.asp , SESAR relevant information can be found at http://www.sesarju.eu/public/standard_page/library_list.html .
6. Topic: AOD. It is a very important decision how to handle the traditional equipment and facilities in “Roadmap,” “Navigation” and “Surveillance” area. Please introduce the U.S. industry strategy (including FAA, airlines, manufacturers) as to how they are operating on this issue.
It is difficult to describe what a “U.S. industry strategy” on this question would be, because in US aviation there are many stakeholders with many differing objectives and constraints. The Boeing point of view is generally that when a new technology/capability has been determined to offer enough significant benefits (safety, capacity, and efficiency) to warrant an investment, all parties should expedite such investment and work collaboratively to change the airspace operation as soon as possible. Additionally, once the new capabilities and operating procedures are prevalent in a particular airspace region, each party should take advantage of cost savings that can be achieved by de-commissioning infrastructure that is no longer needed, and avoid investing in additional out-dated capabilities. These guidelines are considered by Boeing to be necessary for our collective systems to remain economically viable.
7. Topic: AOD. I agree with the point that the near-term benefit is pretty important. And when we talk about the “Near-term,” we can’t avoid talking about how to deal with the issue that aircraft with new capabilities and aircraft without them to operate in same airspace. Is there any suggestion from Boeing on this subject?
The “near term” will always indicate a situation where it is necessary to design the airspace operation in such a way that the new and the old capabilities can both be used. This can mean a variety of different methods, anywhere from segregating traffic flows to allowing a dynamic mixing of flow. An example of segregation would be to reserve one runway exclusively for equipped or un-equipped for some or all of the day, or to restrict airspace segments based on equipage. A dynamic mixing of flow would imply that runways and airspace segments accept both new and old equipage simultaneously, which implies that ATC procedures and automation tools must be designed so that the operation remains at the required safety, capacity and efficiency levels. The choice for each airport and airspace region will be heavily dependent on the expected level of new equipage, and on policy direction.
8. TA vs. CDA. What is major difference between TA and CDA?
Continuous Descent Arrivals (CDA) and Optimized Profile Descents (OPD) essentially provide a definition of the most beneficial descent profile, given all airspace and operational constraints. 3D Path Arrival Management (3D PAM) and Tailored Arrivals (TA) provide a definition of the operational context to enable CDAs/OPDs in a particular technology environment: CDA/OPD operations from Top of Descent (TOD) to the Terminal Maneuvering Area (TMA) entry or runway threshold, voice or data link operations, operations with/without ground automation support, etc. The end state Tailored Arrivals concept provides a data link solution with ground automation support for high traffic conditions, from TOD to the runway threshold.
9. The management, promotion and implementation of CMM aviation system. The modernization of CMM aviation system fell behind the requirements of national modernization development. Should we consider making new technologies part of operational approval requirements? It will be helpful to safe and on-time operation. Without making it a requirement, no real action will occur.
It is difficult to understand this comment. Our understanding of this note is that it is not a question, but is a recommendation. It states civil aviation system modernization should be integrated in the National Modernization plan. Airlines also should be partners of the National Modernization plan which will shorten the plan implementation schedule.
Panel Questions from July 22, 2009 afternoon:
10. Topic: ADS-B. How many ground based stations will be needed to cover mainland China with ADS-B? How much investment will be involved? What about in Australia?
The ground station requirements will be dependent upon the specific ADS-B implementation plan in China. Example: ADS-B Out applications in non radar airspace may initially be focused on Western China. Existing radar surveillance coverage along the Eastern seaboard would not immediately require ADS-B Out capability.
11. Topic: ADS-B implementation. Why does ADS-B Out need to be implemented before ADS-B In? Why not simultaneously?
ADS-B-In can be done simultaneously with ADS-B-Out in special cases, such as the Tibetan Plateau, for example. In most regions it makes sense to implement ADS-B-Out first in order to accomplish the minimum set of airborne equipage (transponder and GPS), to develop operational procedures using ADS-B, and to gradually obtain controller/pilot acceptance. ADS-B-In requires a significant investment in airborne equipage (flight deck displays) that could be justified if there are immediate operational benefits.
12. Will the government take the lead in PBN new technology implementation or is it up to the airlines to complete on their own?
CAAC FSD has taken the lead in this matter.
13. Topic: CDA. If China implements CDA/TA, what work needs to be done? For example, airplane retrofit, ground infrastructure construction?
CDA implementation will depend on the desired traffic levels the operational environment is targeted to support. This will define the technology requirements in terms of communications, ground automation requirements and avionics. Enabling CDAs in relevant traffic conditions will at least require ground automation support for Time Based Metering and Trajectory Generation with tools such as the En-route Descent Advisor. The end-state Tailored Arrivals will require supporting ground automation as outlined above, datalink capabilities in air and ground systems and, at a minimum, RNAV and VNAV capabilities in aircraft. However, solutions without data link support, such as 3D Path Arrival Management (3D PAM) with dynamic trajectory generation in ground automation or solutions with static route structures (i.e. pre-defined flight paths) are feasible as well, providing early benefits.
14. Topic: ADS-B. The Boeing presentation said “the UAT was adopted due to the contingence of the 1090ES.” But some voice from FAA show that the UAT was remained and adopted in GA, for it is free service of METO and flight information. Would you please give some clarification?
UAT was adopted by FAA, but not for technical reasons. Dual systems result in latency that can operationally derogate the performance of the system.
15. Topic: ADS-B technology for ground and airborne surveillance. The ADS-B Out signals travel line-of-sight (LOS) from transmitter to receiver. Please explain its meaning.
The definition of line-of-sight is: an unobstructed path between sending (e.g. airplane transmitter) and receiving (e.g. ground station receiver) antennas. The performance of ADS-B Out can be adversely impacted by terrain that may block ground station signals at low altitudes.
16. Topic: Advanced Arrival Management: Application of RNP in high traffic arrival operations. How do the FMS and Datalink cooperate in the airworthiness aspect? Do we need something like airworthiness for avionics on ground facility? If yes, how is that done?
Integrated datalink will be an important enabler for RNP operations in all phases of flight. Integrated datalink provides the capability to directly transfer uplinked data into the Flight Management System (FMS) without the need for manual entry of the data by the pilot. Certification of integrated FMS / Datalink functionality is provided for in the US by the FAA Part 25 certification of an airplane. Hence all airplanes delivered with integrated datalink are airworthy with respect to datalink functionality and integrated FMS/datalink capabilities.
FAA Part 121 authorization allows the operational use and applications of a particular airplane equipage and capabilities in a particular operational environment. Within this process airlines need to show how the aircraft and capabilities will be used by the flight crew in the conduct of particular procedures and that the airlines have crew procedures to fly them. Airlines also have to show the capability to execute non-normal procedures and the proper training to perform normal and non-normal procedures. This is not limited to FMS and datalink.
Ground automation certification is the responsibility of the Air Traffic Service Provider (ATSP) but requires inclusion of the appropriate parts of an airline operations center automation and that on the aircraft. The assessment for use in advanced arrival management is subject to safety management review processes that consider responsibilities, capabilities and performance of each component in the operation. The process typically starts with a detailed description of System Requirements and Objectives (SR&O). The SR&O details functional and system requirements and addresses potential operational issues and mitigation strategies. This helps to establish the operational framework including aircraft conduct of procedures, and ground system/ATM/AOC interactions. Detailed validation and verification processes throughout the development of ground automation assures that the systems, interfaces, and operations will be as expected. The ATSP may also need other processes for managing and validating procedure data and flight information. Details of this process and associated authorizations are subject to either regulatory criteria and/or the operational approvals granted.
17. Topic: ADS-B. As we know, the new technology will be applied in the next two decades, and more than 50% of airplanes should be equipped with ADS-B. Maybe the actual performance needs more time to be evaluated during the usage in the future.
The operational capability of new technology must include cost-benefits analysis prior to investment decision. Adequate equipage levels will not be obtained if there are not operational benefits, thus ADS-B In procedures will need to be developed. It is assumed that there are significant user benefits for ADS-B In operations that will justify the costs of the airborne equipage. Any delay in procedure development will cause a delay in equipage, thus delay user benefits.
18. Topic: Safety aspect of ADS-B. Would it be a kind of threat that everyone could receive ADS-B signal? What do you suggest to ensure the safety of commercial flight?
ADS-B security is an important issue that must be addressed by the states implementing ADS-B. This is a policy issue.
19. Topic: ADS-B. Could you please say more about UAT and VO2-4 (?or VD2-4) technology and implementation?
As addressed in the ADS-B presentation, Boeing recommends and supports a single 1090 extended squitter system.
Panel questions from July 23, 2009
20. Topic: SWIM. What are the main hurdles in the development of SWIM?
The main hurdles in the development of SWIM include organization, culture, standards development and infrastructure. Managing information system wide requires changing the way the organization is structured. In addition, while everyone wants to get all available information and everyone agrees that sharing information is an overall benefit, it is very difficult for organizations to give up information. Creating standards that allow establishment of a common language for sharing information takes a lot of time and effort because today there are many different versions of the computer information. It is as hard as establishing a common voice language. The infrastructure does not have to be the same everywhere but limiting the variations makes it easier to achieve interoperability.
21. SWIM: Currently, what is the biggest challenge to implement the SWIM? Security? Or investment? Are there any new roles that will be added into the system to manage the SWIM?
The biggest challenge is changing the organizational culture, see #24 above.
Security is an attribute that requires work but there are both standards and technologies that allow for building in information security. The best way to handle the investment issues is to apply SWIM to new systems as they are being designed.
Retrofitting is expensive but can also be justified based on saved maintenance costs. The best way to manage SWIM is to establish a Chief Information Officer with the authority to manage the information System-Wide.
22. SWIM: Please give a clear definition of the “service” and “SOA.” And the differences between the “service” and function of application. Are there any differences between NextGen SWIM and SESAR SWIM?
Information services refer to delivery of information using a combination of computers and communication networks. This is different than the paradigm used for most of the computer systems developed over the past 30 years. They were built with the idea that software was written as applications that manipulated data. What little interconnection between systems that was required was done through individually developed interfaces. An information service usually uses several computers and applications to gather, manipulate and deliver the information. Think of a weather service as opposed to a weather forecast application.
SOA (Service Oriented Architecture) starts with a collection of services and builds computer applications and networks to gather, manipulate, and deliver the information required for those services. The networks are shared among many services rather than individually purpose built. The shared distribution is more costly for sharing information between just one or two applications but is much more cost effective when sharing among many services.
In concept NextGen SWIM and SESAR SWIM are the same. AIXM (Aeronautical Information on XML) and work being done on Weather for XML are being developed jointly between SESAR and NextGen. There is still much work to be done to make standards for sharing traffic information but that is being done jointly as well.
23. Datalink. What kind of new technologies of datalink can be applied?
Eurocontrol and the FAA are working on the implementation of ATN-based VLD Mode 2 for European and US ATS domestic operations in the 2011-2017 timeframe. Eurocontrol has already published a mandate for this datalink equipage, and the FAA is expected to follow suit shortly. Thus, this datalink solution will likely become available on Boeing and Airbus aircraft in this timeframe. Other datalink technologies could be developed and proposed, but in this timeframe it is unlikely that they can be affordable for Air Traffic Services.
24. ADS-B. Would you talk about ICAO policy and standards on the operation, development and application of ADS-B?
ICAO’s ATM Requirements Plan is looking at surveillance issues and is currently evaluating alternatives, but there are no definite requirements at this time. Boeing will continue to monitor ICAO-related developments.
25. ADS-B: Can ADS-B messages be sent and received via satellite datalink? The aircraft flying trans-Pacific routes could not connect with ground station, could ADS-B be adopted for ground surveillance?
No, ADS-B Out will be transmitted over 1090 MHz only. ADS-B In applications such as In-Trail Future Air Navigation System (FANS) ADS-B-Addressed uses satellite datalink, and could be used in oceanic airspace.
26. GNSS: Core constellations?
“Core constellations” refer to sets of satellites that form autonomous satellite navigation systems. For example, GPS is a core constellation. An SBAS satellite is not considered a core constellation because a user cannot determine his or her position by using only the SBAS satellite. Augmentation is always done relative to a service or signals provided by one or more core constellations.
27. GNSS: Please give an introduction of ARAIM and RRAIM concept.
RAIM stands for Receiver Autonomous Integrity Monitoring. RAIM algorithms are a means for a GPS receiver to detect and mitigate failures of satellites or other parts of the core satellite systems that could cause an unacceptably large position error. The basic idea is that in order to determine a 4 dimensional position, 4 measurements (i.e. pseudo-range measurements) are required. If 5 or more measurements are available, then the system is ’over-determined’ (i.e. has more information than is needed to solve for the 4 unknowns). If the system is over determined, all the available measurements are used to solve for the 4 unknowns by making a "best fit" of the available data. If a large failure exists in one measurement, then the data will be inconsistent. A RAIM algorithm estimates the inconsistency in the fit of the data and uses this as an indication of a potential failure condition.
ARAIM stands for Absolute RAIM. This is the most common type of RAIM algorithm used today. An ARAIM algorithm takes each set of measurements as an independent set and estimates the inconsistency of the fit without regard to any past measurements or the previous states of the system. This is sometimes referred to as a ’snapshot’ algorithm.
RRAIM stands for Relative RAIM. In this type of RAIM algorithm, some knowledge of the characteristics of the error sources is used along with some historical information about the state of the system to improve the Fault detection and/or Isolation capabilities. This often involves propagating a position forward in time based on carrier phase observations only. Because the carrier noise is much smaller, the thresholds for errors can be set much tighter. Any large, slow-moving biases will be projected into the cycle ambiguity estimate. Higher dynamic errors can be detected very quickly by the carrier based RAIM. The longer bias like errors can be addressed by averaging the noise over time and relying on assumptions about the overall exposure to the errors. This may include some external monitoring by a system (e.g. SBAS) that can detect or mitigate large, slowly evolving biases, but may have an unacceptably long time to alert. RRAIM is in general not a "snap-shot" algorithm and has some "memory". There is a trade-off between the external monitoring, the time to alert and assumptions about the dynamics of the error characteristics.
28. GNSS:
(1) What do you think about the use of CATI GBAS in USA?
There are two sites where GBAS is currently being deployed in the United States: Memphis, Tennessee and Newark, New Jersey. However, the interest in GBAS has consistently been higher outside the United States. The most interesting applications are really going on elsewhere (e.g. Sydney, Australia, or Bremen, Germany).
(2) Would you give some information about the Roadmap of CATI and II Avionics and Ground System development in USA?
GBAS capable avionics have already been developed by one company (Collins) and are nearly complete for a second (Honeywell). These avionics are based on RTCA DO-253B and are often referred to as "CAT I" GBAS equipment. However, it is probable that the use of these avionics will not be limited to approach to CAT I minimums (i.e. 200ft DH and ½ mile RVR). It is probable that operational approvals for approach to CAT II minimums will eventually be granted. These approvals may rely on the use of HUD or autopilot operations in conjunction with the so-called "CAT I" GBAS system. (There is precedent for exactly this sort of thing in the use of a "Facility Category I" ILS ground station to support operations to CAT II minimums which are allowed today.)
Discussions among industry and regulators regarding use of first generation GBAS for operations with lower than CAT I minimums have been initiated by Eurocontrol. FAA currently has no formal plans for a federally funded acquisition of GBAS to support CAT I operations in the United States. The projects that are being pursued in the US are "non-federal" programs principally funded by industry. FAA participation is in support of applications made by airlines and as part of a risk reduction program aimed at the eventual acquisition program for CAT IIIb capable GBAS ground stations.
Standards for a next generation GBAS have been under development by ICAO for the last several years and are nearing completion. This second generation of GBAS will be backwards compatible with the first generation, but will enable provision of an additional service type intended to support fail-operational landing operations (such as approach and landing in CAT IIIb conditions). It is anticipated that early operational approvals based on this development could be achieved by 2014. How quickly this happens depends on the demand. Some teams composed of an airline, a service provider and a regulator must work together on a pioneering "proof of concept" program. The program should culminate in the first operational approval of GLS for CAT IIIb operations. Such a program would produce the necessary airworthiness and operational approval criteria needed for GLS CAT IIIb operations.
29. GNSS:
(1) How does GLS guide the airplane into glide path? Any difference with ILS?
From the standpoint of transition from RNAV to GLS, it is identical to ILS. The FMS flys the RNAV procedure and the Localizer (LOC) and Glideslope (GS) modes are "armed". When the airplane gets within a certain distance to the reference path (centerline or Glideslope) the autopilot automatically transitions through a capture maneuver to the LOC or GS mode. This operates in exactly the same way as ILS. However, the performance in capture is improved due to the cleaner nature of the GLS guidance signals at the limits of coverage.
(2) What are the advantages and disadvantages of GLS?
Advantages of GLS:
- One ground station serves all runway ends at an airport, possibly with multiple approaches to the same runway end (e.g. displaced thresholds, multiple glide paths etc.).
- No Critical and Sensitive Areas to protect – (may result in height runway utilization).
- Superior performance (i.e. cleaner signal without beam bends).
- Reduced flight inspection.
- Can provide increased accuracy and integrity with height availability in the terminal area to support RNP applications.
Disadvantages of GLS:
- GLS is a new system, so equipage will take time. Some facilities may need to maintain ILS for a lengthy transition period.
- New system will require new flight inspection gear. However, requirements for periodic flight inspection are reduced or eliminated.
30. GNSS: Describe how to coordinate and standardize GPS altitude and pressure altitude. (Aircraft needs pressure, altitude, GNSS provides actual physical altitude.)
GPS sensors today output height relative to Mean Sea Level (MSL). (This is done using a model of the earth’s Geoid relative to the Ellipsoid that is used by GPS as the basic datum.) After baro-correction, pressure altitude also produces height relative to MSL. However, even though expressed in the same coordinate frame, GNSS height and pressure altitude are not interchangeable. For many reasons, pressure altitude will likely remain the principle source of altitude information to be used operationally. In all cases today, GNSS vertical positioning is only used when a reference to a runway coordinate system is appropriate (e.g. LPV or GLS operations). FAA is about to release an AC concerning proper use and annunciation of GNSS height in the cockpit. (AC 20-163)
31. GNSS: Is US GPS reliable? The GPS is controlled by US Military. It is said that US GPS might crash next year due to lack of funds.
Historically, GPS has proven to be very reliable. Boeing anticipates that it will continue to be reliable. However, there has been much discussion in the press of a study recently done by US General Accounting Office (GAO) that indicates the health of the constellation could degrade over the next few years (starting as early as next year). The analysis in the GAO report is somewhat pessimistic as it doesn’t take into account some mitigation alternatives that are available to the US Department of Defense (DoD) such as power management and the potential to return to service "spare" satellites still on-orbit but "deactivated". Having said that, there is little margin in the current programs so any delay in launching satellites could impact the health of the constellation. The GPS constellation has never been larger (32 operating satellites and several on-orbit "deactivated" satellites that could be pressed back into service). Additionally, the constellation has never been older in terms of average age. Boeing is studying the situation and will be watching closely.
The US DoD has publicly stated that its intent is to continue the operation of GPS to the same high standards we have enjoyed during the last few years. The DoD also acknowledges that there are risks that could make maintenance of the constellation at the high degree of redundancy we have seen (i.e. 30+ satellites rather than the nominal 24 satellites) impossible to maintain. Every organization that uses GPS should be aware of those risks and plan accordingly. For example, for all operations that use GPS, some contingency planning should be done to address what happens should GPS become unavailable. Loss of GPS service is always a possibility if for no other reason than unintentional RF interference. Hence, some planning with respect to alternative operational procedures or other ways to mitigate unplanned service outages is necessary.
If there is some reduction in the robustness of the GPS constellation, it is unlikely to appear as a "crash" and be more likely to happen as a gradual degradation. For example, service outage periods could gradually become more frequent and longer. As a means to mitigate the effects, users with significant operations should be considering the use of augmentations to mitigate the potential for unacceptable service availability. For example, around high value airports where capacity enhancements are critical RNP availability can be protected by installing a GBAS that supports the GBAS Positioning Service (GBAS/PS). In states where SBAS service is available, SBAS could also be used.
32. GNSS: Is the accuracy of LAAS reference receivers related to location and quantity? How many receivers does an airport need? How to determine the number needed?
The accuracy of a GBAS ground station is partly determined by the number of reference receivers. Because the differential corrections are produced by averaging the measurements made by all the reference receivers, the measurement noise gets averaged. However, this is not the prime reason for including multiple reference receivers. The primary reason is to allow the measurements to be cross checked to detect failures of individual reference receivers or multipath into a single reference receiver. In general, the greater the redundancy, the stronger the monitoring capability. Furthermore, use of more than the minimum number of reference receivers required allows the system to be "fail-operational". For example, if a ground station can generally produce adequate accuracy and integrity with 3 reference receivers, then operating with 4 reference receivers makes the operation insensitive to the failure of one reference receiver.
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发表于 2010-8-5 20:33:50
