Application US A,3704845, B64C 1/10

Patent owner:  Michael Ord, 5267 Wilkins Avenue, Pittsburgh, Pa.          Dec.5,1972



A method and system for preventing airplane hijacking features the following:

1.      The cockpit is isolated from the cabin to give passengers a sense of safety, but communication must be ensured. The buttons fixed in the cabin keep the cockpit informed of such things as oxygen shortage, fire alarm, medical accident, device fault and any other trouble.

2.      The isolating door between the cockpit and the cabin is restricted, and the door and its associated isolating walls are made of bulletproof materials.

3.      The voice communication system of the audio system is a one-way system from the cockpit to the cabin, preventing the words of the hijackers from being heard.

4.      This invention warns the passengers in advance.

Comments:   The key idea of the patent is that the pilots are locked in the cockpit so that the hijackers can not communicate with the pilots. Even if the hijackers hold any hostage, the pilots will not open the cockpit without hearing anything. Even if the hijackers do as indicated in Fig. 4 22, the pilots may choose to stay if the situation is not critical.


1.       The US patent invention does not allow for any possible neglect of the pilots.

2.       The pilots may not come even if all buttons in Fig. 4 22 are pressed.

3.       Are the bulletproof wall and door of the cockpit soundproof? The hijackers know perfectly well how to raise hell, and they will kill one person every five minutes until the pilots come out!

4.   The pilots may rely on their unreliable perception and reasoning to decide whether to open the door of the cockpit, therefore the US patent invention is inadequate to deter hijacking.


The US patent invention in 1972 has drawn upon the experience of the previous three patents of China but still leaves much to be desired. By contrast, the double-door structure specified in Mr. Zhen-man Lin patent is original, the “Single-person checkroom” is a natural evolution of modern technology, and the five-finger mold is unprecedented. The single-person checkroom of the double-door structure precludes the effect of human factors and the five-finger mold makes the system flawless. The hijacking prevention system of Mr. Zhen-man Lin is so original that the US patent application does not affect the patent application of Mr. Zhen-man Lin.