估计很多人，应该都和我一样，在机务刚入行时会碰到过这样的情形：
每当要做气象雷达测试，老师傅都会喊，还没有孩子的赶紧走开，站到机头后面去，或者上飞机上呆着。
圈内，一直都有流传被气象雷达扫了后会导致不孕，也有人说以后生女儿的概率大幅上升……
这些传言到底可信度有多大呢？
01
气象雷达是飞机上重要的气象探测设备，机组平时也使用频繁，工作中难免会有疏漏，所以偶尔也有落地忘记关的时候。
比如有架飞机，落地后机组把雷达选择开关放到了TEST位，但由于 EFIS上选择了centered VOR模式，所以注意到气象雷达没关。
机务上机后检查发现气象雷达在TEST位，没有关闭，投诉了机组。
首先，机组肯定是有错的，没有按手册要求来检查雷达关闭。
而我更关心的问题其实是，被气象雷达扫啦，对人体影响到底有多大？
一直以来，大家都是在口口相传，但事实究竟是怎么样呢，有没有相关的手册文件能给出答案。
02
为了搞明白这个问题，首先看下我们的AMM手册。
目前我们737NG机队安装三种雷达：Honeywell的RTA-4B 和 RDR-4000，Collins的 WXR-2100。AMM 34-43-00/501分别对应这三种构型气象雷达操作测试程序。
R63:Jun 15/2017
WARNING:
DO NOT OPERATE THE WEATHER RADAR IN A HANGAR OR NEARER THAN 160 FEET FROM PERSONNEL. IF YOU DO NOT OBEY THESE PRECAUTIONS, INJURIES TO PERSONNEL CAN OCCUR.
都有要求人员在160英尺（48.768米）以外。
要求距离这么远，看来气象雷达工作时危害确实很大呢，但是……我之前怎么没发现呢？
我又去翻了下之前版本的手册：
R61:Oct 15/2016
WARNING:
DO NOT OPERATE THE WEATHER RADAR WHEN PERSONNEL ARE IN THE AREA USUALLY CONTAINED BY THE AIRCRAFT NOSE RADOME. DO NOT OPERATE THE WEATHER RADAR IN A HANGAR. IF YOU DO NOT OBEY THESE PRECAUTIONS, INJURIES TO PERSONNEL CAN OCCUR.
原来，AMM手册进行了改版……
03
只好咨询波音了，得到的回复如下：
1. 气象雷达在正常工作模式和TEST模式辐射问题
Boeing advises that based on analysis and tests conducted on various WxR System installations including the Honeywell RDR-4B, RDR-4000, and Rockwell Collins WXR-2100, even when these systems are normally operating (WX mode, WX+T mode, etc.) there is low power output, and therefore there is no threat to manufacturing, maintenance or ground crew personnel working under or around the airplane (the safe distance from the WxR antenna under normal operation is around a foot in length).
Note that in TEST mode, the WxR antenna emits low RF energy for only around one second, after which it does not radiate at all. If the unit is selected to TEST mode there is also no danger to maintenance personnel working around or under the airplane.
Boeing recommends turning the WxR system OFF when maintainers are working inside the opened Radome area of the airplane where they could potentially be in close proximity to the WxR antenna.
针对这三种雷达，其实只要人不是在雷达罩内，不管雷达是在工作模式还是在测试模式，都是对身体没有危害的。在TEST模式，天线只在开始发射1秒，后面就不发射了。
2. AMM手册里的160FT警告问题
Older weather radar systems generally output much higher RF power and include fixed antenna configurations that would result in much higher radiation exposure levels to maintenance personnel working in front of the airplane. For some systems, the recommended distance from an operating WxR system is over 100 feet. To accommodate the various systems, Boeing added the AMM warning to ensure the safety of maintainers and others near the airplane that may be unaware of the potential dangers if the system was operating.
Because of the lower power levels in the newer WxR systems, the 160 foot restriction is no longer a requirement. Although not a hard requirement, Boeing still recommends that the WxR System be turned Off or be in Test mode when personnel are working around the airplane. If personnel are working inside the Radome area of the airplane, the WxR System should be turned Off to avoid potential exposure.
3. AMM手册改版和哪些雷达系统操作时需要远离100FT以外
Boeing will revise the AMM to modify the 160 foot warning for personnel working around the airplane. This change is expected to be available in the AMM revision scheduled for 15 February 2018.
Weather Radar systems made by Bendix, Sperry, RCA, and Motorola that used higher power, fixed antenna installations required that personnel be positioned over 100 feet from the airplane. Note that none of these older systems would apply to 737NG model airplanes currently operated by China Eastern.
看来之前那些关于气象雷达的传言，其实是不适用我们现在的飞机的啊。
后面又去百度了下资料：
前几代的气象雷达使用磁控和抛物面天线，发射功率达几十千瓦，辐射较强 。
而现代气象雷达普遍采用平板缝隙式天线，并使用X带频率8000～12500MHz，波长通常在2.4～3.75cm。天线发射圆锥形波束，波束的主瓣很窄，宽度一般为3°～5°。天线发射的能量主要集中在主瓣宽度内，由于天线的方向性强、增益大，使得雷达发射功率大大降低，峰值功率仅一百多瓦，电磁辐射也随之大大减小。
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