Flight instruments have evolved remarkably from yaw string to modern pitot static systems. A state-of-the-art pitot static system provides the aircraft computers with the most vital set of data: airspeed, altitude, and vertical speed.
飞行仪表已从偏航弦发展到现代皮托静压系统，发生了显著的变化。先进的皮托静压系统为飞机计算机提供最重要的数据：空速、高度和垂直速度。
It is a pilot’s nightmare to lose the aircraft’s pitot-static system in mid-flight as it endangers the safety of all onboard. Here is a complete guide on how a typical pitot static system works and how bad pitot static system errors could affect a flight. More importantly, we have tailored an equation to troubleshoot and identify all failure modes.
飞行途中飞机的皮托静压系统失灵是飞行员的噩梦，因为它会危及所有机上人员的安全。本文将提供一份完整的指南，介绍典型的皮托静压系统的工作原理以及严重的皮托静压系统故障可能对飞行造成的影响。更重要的是，我们定制了一个公式，用于排除故障并识别所有故障模式。
Lessons learned 经验教训
A piece of tape bringing an airliner down
一条胶带让一架客机坠毁
A maintenance worker applied tape on the static port(s) to clean the airplane exterior. Upon finishing his work, he forgot to remove the tape and the aircraft took off with a blocked static port(s).
一名维修工人用胶带封住了静压孔，以清洁飞机外部。工作完成后，他忘记撕掉胶带，导致飞机在静压孔被堵塞的情况下起飞。
Pilots on Aeroperú Flight 603 were facing erroneous indications on the airspeed indicator, altimeter, and vertical speed indicator. The aircraft had lost altitude unknowingly to the pilots and crashed into the sea killing all 70 people onboard.
秘鲁航空 603 航班的飞行员发现空速表、高度表和垂直速度表显示错误。飞机在飞行员不知情的情况下失去了高度，坠入大海，机上 70 人全部遇难。
A wasp net killing 189 people
蜂网致189人死亡
Birgenair Flight 301 stalled and crashed into the Atlantic ocean followed by a stall and a spin. A wasp net on the captain’s pitot tube gave rise to erroneous airspeed indications that ultimately ended up crashing the aircraft and killing 189 souls onboard.
伯根航空301航班失速坠入大西洋，随后失速并旋转。机长皮托管上的蜂网导致空速指示错误，最终导致飞机坠毁，机上189人遇难。
Pitot static system and possible errors
皮托静压系统及可能出现的误差
A typical pitot static system comprises two pitot tubes, two static ports (another one may be available as the alternate static source), and the related instruments: an airspeed indicator, an altimeter, and a vertical speed indicator.
典型的皮托管静压系统包括两个皮托管、两个静压口（另一个可用作备用静压源）和相关仪器：空速指示器、高度计和垂直速度指示器。
This is one of the simplest yet vital systems available in the aircraft. Unlikely the other systems, troubleshooting is fairly easy. The entire system deals with air and a blockage in the air passages is the most common error. With that said, it is time to master how a typical pitot-static system failure could occur and tactics to pinpoint the error.
这是飞机上最简单却又至关重要的系统之一。与其他系统不同，它的故障排除相当容易。整个系统都与空气有关，而气道堵塞是最常见的故障。话虽如此，现在是时候了解典型的皮托静压系统故障是如何发生的，以及如何找出故障的策略了。
A skim through the pitot-static system
皮托静压系统概述
In pitot static systems,
在皮托静压系统中，
The airspeed indicator is the only instrument that receives inputs from the pitot tube.
空速指示器是唯一从皮托管接收输入的仪器。
All three pitot-static instruments receive inputs from the static ports, while vertical speed indicators and altimeters rely only on static ports.
所有三个皮托静压仪器都从静压口接收输入，而垂直速度指示器和高度计仅依赖静压口。
In airspeed indicators, 在空速指示器中，
The pressure inside the instrument case is the static pressure from the static ports.
仪器箱内的压力是来自静压口的静压。
Ram air pressure (dynamic + static pressure) from the pitot tube is routed directly into the diaphragm.
来自皮托管的冲压空气压力（动态+静态压力）直接进入隔膜。
Movement of the diaphragm occurs due to the dynamic component of the air pressure.
隔膜的运动是由于气压的动态分量而发生的。
Pitot tube 皮托管
A pitot system taps ram air from the free stream airflow and sends the air into the airspeed indicator. Within the airspeed indicator, a diaphragm obtains the dynamic pressure with the aid of ram air pressure from the pitot tube and static air pressure from the static port. A blocked pitot tube can be further divided into three categories depending on the location of the blockage.
皮托管系统从自由气流中抽取冲压空气，并将其送入空速指示器。在空速指示器内，膜片借助皮托管的冲压空气压力和静压孔的静压获得动压。根据堵塞位置，皮托管堵塞可进一步分为三类。
Main intake blockage 主进气口堵塞
A blockage that occurs at the main air intake is the most peculiar type of blockage found in pitot tubes. This prevents the entrance of ram air into the tube allowing only static air that enters via the drain hole.
主进气口堵塞是皮托管中最常见的堵塞类型。这会阻止冲压空气进入皮托管，只允许静态空气通过排水孔进入。
As the needle of the airspeed indicator is driven by the dynamic pressure (which is the pressure difference between the pitot pressure and static pressure), the unavailability of dynamic pressure results in zero indication.
由于空速表指针是由动压（即皮托管压力与静压之间的压力差）驱动的，因此如果没有动压，则会导致指示为零 。
Drain hole blockage 排水孔堵塞
When the blockage occurs at the drain hole, the airspeed indicator continues to function without any errors. As the drain hole is unable to cater to its intended function- draining water trapped within the pitot tube- inaccurate indications may be shown to the pilots.
当排水孔堵塞时，空速指示器仍能正常工作。由于排水孔无法发挥其预期功能——排出皮托管内的积水，飞行员可能会看到不准确的指示 。
Both main intake and drain hole blockage
主进水孔和排水孔均堵塞
When this dual blockage occurs, the pressure inside the blocked pitot tube is unchanged. In level flight, there will be an indication on the dial but the pointer remains frozen regardless of the aircraft’s actual airspeed.
当发生这种双重堵塞时，堵塞的皮托管内的压力保持不变。在平飞时，无论飞机的实际空速如何，表盘上都会有指示，但指针仍然静止不动 。
A change in the airspeed indication is observed only when the aircraft changes its altitude. In this instance, the airspeed indicator acts like an altimeter. Here is how it happens.
只有当飞机改变高度时，空速指示才会发生变化。在这种情况下，空速指示器的作用类似于高度计。其工作原理如下。
When the aircraft climbs: With increasing altitude, static pressure that acts against the diaphragm reduces, hence, the diaphragm expands indicating an increment of airspeed.
当飞机爬升时： 随着高度的增加，作用于横膈膜的静压力减小，因此横膈膜膨胀，指示空速的增加。
When the aircraft descends: With decreasing altitude, static pressure that acts against the diaphragm increases, hence, the diaphragm contracts indicating a reduction of airspeed.
当飞机下降时： 随着高度的降低，作用于横膈膜的静压力增加，因此横膈膜收缩，表明空速降低。
What takes you out of the trouble in pitot system errors?
什么能帮助您摆脱皮托管系统误差的困扰？
Turning on pitot heat will address all three errors as pitot probes are susceptible to ice formation as they are exposed to the free stream airflow. As shown in image 01, one heating element is placed close to the intake and another one close to the drain hole. A heated pitot tube can keep the two holes clear and pilots out of trouble.
开启皮托管加热器可以解决所有这三个问题，因为皮托管探针暴露在自由气流中容易结冰 。如图 01 所示，一个加热元件放置在靠近进气口的位置，另一个靠近排水孔的位置。加热皮托管可以保持两个孔的畅通，避免飞行员遇到麻烦。
When the pitot tube is blocked by something else, like a wasp net in the Birgenair crash or when the aircraft departed with pitot tube covers installed, pitot heat will longer be a savior.
当皮托管被其他东西堵塞时，例如伯根航空坠机事故中的黄蜂网，或者飞机起飞时安装了皮托管盖，皮托管加热将不再能起到救星的作用。
Static port 静态端口
A blockage on a static port will take out the static source from all three instruments killing airspeed indication, altitude indication, and rate of climb. Time to see how each pitot-static instrument behaves with the loss of its static source.
静压孔堵塞会导致三个仪表的静压源全部中断，从而影响空速指示、高度指示和爬升率。是时候看看每个皮托静压仪表在失去静压源后会如何表现了。
Airspeed Indicator 空速指示器
Nothing is amiss until the aircraft changes its altitude.
只要飞机没有改变高度，一切就都没有问题。
When the aircraft climbs- airspeed will be decreased.
当飞机爬升时，空速将会降低。
When the aircraft descends- airspeed will be increased.
当飞机下降时，空速会增加。
Altimeter 高度表
Altitude remains frozen even if the aircraft descends or climbs.
即使飞机下降或爬升，高度仍保持冻结。
Vertical Speed Indicator
垂直速度指示器
Vertical speed remains at zero as the diaphragm does not move.
由于横膈膜不动，垂直速度保持为零。
An alternate static source is located within the aircraft cabin (in an unpressurized area) to be used when the external static port blockage occurs. Pilots switch the static source with a toggle switch located in the cockpit. With that done, pilots have to correct the airspeed against a calibration chart provided in the flight manual.
飞机客舱内（非加压区域）设有备用静压源，用于外部静压孔堵塞时使用。飞行员使用驾驶舱内的拨动开关切换静压源。切换完成后，飞行员必须根据飞行手册中提供的校准图表校正空速。
Final thoughts 最后的想法
Pitot static system controls some of the most vital flight instruments aboard an aircraft and finding yourself in flight with the system malfunctioning is something straight out of a nightmare for a lot of pilots.
皮托静压系统控制着飞机上一些最重要的飞行仪器 ，对于许多飞行员来说，在飞行过程中发现系统发生故障简直就是一场噩梦。
Pitot static system blockage can show altimeter, airspeed and vertical indicator errors, however it all depends where the blockages occur, so it is important to know how to counter issues like that. Luckily, with this article you should be all set for situations like that.
皮托静压系统堵塞会导致高度计、空速计和垂直指示器出现误差，但这完全取决于堵塞的位置，因此了解如何应对此类问题至关重要。幸运的是，阅读本文后，您应该能够应对此类情况。