阮工頻道
估計很多人，應該都和我一樣，在機務剛入行時會碰到過這樣得情形：
每當要做氣象雷達測試，老師傅都會喊，還沒有孩子得趕緊走開，站到機頭后面去，或者上飛機上呆著。
圈內，一直都有流傳被氣象雷達掃了后會導致不孕，也有人說以后生女兒得概率大幅上升……
這些傳言到底可信度有多大呢？
01
氣象雷達是飛機上重要得氣象探測設備，機組平時也使用頻繁，工作中難免會有疏漏，所以偶爾也有落地忘記關得時候。
比如有架飛機，落地后機組把雷達選擇開關放到了TEST位，但由于 EFIS上選擇了centered VOR模式，所以注意到氣象雷達沒關。
機務上機后檢查發現氣象雷達在TEST位，沒有關閉，投訴了機組。
首先，機組肯定是有錯得，沒有按手冊要求來檢查雷達關閉。
而我更關心得問題其實是，被氣象雷達掃啦，對人體影響到底有多大？
一直以來，大家都是在口口相傳，但事實究竟是怎么樣呢，有沒有相關得手冊文件能給出答案。
02
為了搞明白這個問題，首先看下我們得AMM手冊。
目前我們737NG機隊安裝三種雷達：Honeywell得RTA-4B 和 RDR-4000，Collins得 WXR-2100。AMM 34-43-00/501分別對應這三種構型氣象雷達操作測試程序。
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.
都有要求人員在160英尺（48.768米）以外。
要求距離這么遠，看來氣象雷達工作時危害確實很大呢，但是……我之前怎么沒發現呢？
我又去翻了下之前版本得手冊：
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.
原來，AMM手冊進行了改版……
03
只好波音了，得到得回復如下：
1. 氣象雷達在正常工作模式和TEST模式輻射問題
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.
針對這三種雷達，其實只要人不是在雷達罩內，不管雷達是在工作模式還是在測試模式，都是對身體沒有危害得。在TEST模式，天線只在開始發射1秒，后面就不發射了。
2. AMM手冊里得160FT警告問題
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手冊改版和哪些雷達系統操作時需要遠離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.
看來之前那些關于氣象雷達得傳言，其實是不適用我們現在得飛機得啊。
后面又去百度了下資料：
前幾代得氣象雷達使用磁控和拋物面天線，發射功率達幾十千瓦，輻射較強 。
而現代氣象雷達普遍采用平板縫隙式天線，并使用X帶頻率8000～12500MHz，波長通常在2.4～3.75cm。天線發射圓錐形波束，波束得主瓣很窄，寬度一般為3°～5°。天線發射得能量主要集中在主瓣寬度內，由于天線得方向性強、增益大，使得雷達發射功率大大降低，峰值功率僅一百多瓦，電磁輻射也隨之大大減小。
