最近看文献被一个术语搞的晕头转向，pushback词典解释是后推。稍微专业一点的说是：n. 飞机推迟起飞。这我就蒙了，啥意思嘛？所以就有了这篇解释
Pushback
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In aviation, pushback is an airport procedure during which an aircraft is pushed backwards away from an airport gate by external power. Pushbacks are carried out by special, low-profile vehicles called pushback tractors or tugs.
由于航站的登机口通常相当狭窄，没有足够的空间让飞机调头转向，虽然许多飞机能够使用飞机发动机的推力反向器改变气流方向并自行倒退，但发动机的喷射气流可能会因此损坏附近的建筑物与设备，并扬起地面的异物后再吸入发动机导致发动机故障。因此，后推是使飞机离开登机口的首选方法。在繁忙的机场，后推作业需要得到航空交通管制员的批准，以协调滑行道的交通。因此，如何有效管制后推作业亦是航空交通管制员的重要课题。
Although many aircraft are capable of moving themselves backwards on the ground using reverse thrust (a procedure referred to as a powerback), the resulting jet blast or prop wash might cause damage to the terminal building or equipment. Engines close to the ground may also blow sand and debris forward and then suck them into the engine, causing damage to the engine. A pushback is therefore the preferred method to move the aircraft away from the gate.
Pushbacks at busy aerodromes are usually subject to ground control clearance to facilitate ground movement on taxiways. Once clearance is obtained, the pilot will communicate with the tractor driver (or a ground handler walking alongside the aircraft in some cases) to start the pushback. To communicate, a headset may be connected near the nose gear.
Since the pilots cannot see what is behind the aircraft, steering is done by the pushback tractor driver and not by the pilots. Depending on the aircraft type and airline procedure, a bypass pin may be temporarily installed into the nose gear to disconnect it from the aircraft’s normal steering mechanism.
Equipment
Moving light aircraft
Light aircraft can usually be moved by human power alone. Here, this Aerotechnik EV-97A Eurostar is being pulled into position for refueling
Very small airplanes may be moved by human power alone. The airplane may be pushed or pulled by landing gear or wing struts since they’re known to be strong enough to drag the airplane through the air. To allow for turns, a person may either pick up or push down on the tail to raise either the nose wheel or tail wheel off the ground, then rotate the airplane by hand. A less cumbersome method involves attaching a short tow bar to either the nose wheel or tail wheel, which provides a solid handhold and leverage to steer with, as well as eliminates the danger of handling the propeller. These tow bars are usually a lightweight aluminum alloy construction which allows them to be carried on board the airplane. Other small tow bars have a powered wheel to help move the airplane, with power sources as diverse as lawnmower engines or battery-operated electric drills. However, powered tow bars are usually too large and heavy to be practically carried on small airplanes.
Once the pushback is completed, the towbar is disconnected, and any bypass pin removed. The ground handler will show the bypass pin to the pilots to make it clear that it has been removed. The pushback is then complete, and the aircraft can taxi forward under its own power.
后推
(英语：Pushback）是指将飞机推离登机桥或泊位的作业。在航空领域，后推是飞机的标准离场程序之一。
需要后推的理由
由于航站的登机口通常相当狭窄，没有足够的空间让飞机调头转向，虽然许多飞机能够使用飞机发动机的推力反向器改变气流方向并自行倒退，但发动机的喷射气流可能会因此损坏附近的建筑物与设备，并扬起地面的异物后再吸入发动机导致发动机故障。因此，后推是使飞机离开登机口的首选方法。在繁忙的机场，后推作业需要得到航空交通管制员的批准，以协调滑行道的交通。因此，如何有效管制后推作业亦是航空交通管制员的重要课题。
后推方式
后推通常是由一辆特制的牵引车（又称曳引机、后推车）执行，若是小型飞机，可能会采用人力后推。
牵引车
牵引车有两种，一种是无后推杆（Tow Bar Less，缩写成TBL），另一种是传统式，需要后推杆进行作业。无后推杆牵引车只须抱起鼻轮就可以进行后推作业。而传统牵引车则需要用后推杆连接鼻轮。牵引车亦可牵引飞机滑行。
一些飞机须要在后推前插上“转向操作凌驾销装置”（Steering bypass pin），以防止飞行员在后推期间进行任何的转向操作，并保证所有后推时的转向操作由牵引车司机进行。
有时，后推杆会在后推期间与飞机分离，但这种情况不太常见。后推杆上的“推行压力销”（sheer pin）可以保护飞机，防止任何牵引车错误的操作导致飞机损毁。如果“推行压力销”承受过大压力就会折断，后推杆会与飞机分离，以保护鼻轮和机身结构。