What is an airplane patrol?

(Mu Huan Wen)

During the fire prevention period, the aircraft is used to detect and transmit the fire and determine the fire location. 19 15, Washington State Forestry Bureau used aircraft to detect fire for the first time. 1924, Ontario, Canada has also begun to use aircraft to patrol. 193 1 year, the Soviet union set up the first forest aviation fleet, and carried out forest fire prevention on the forest area of Gorky state 1 10,000 hectares, which was popularized to the whole country from 1936, and the aviation forest protection area of 1985 reached 767.5 million hectares. From 6: 438 to 9: 52, China started the air patrol alert work in Daxinganling forest area.

Patrol preparation

According to the fire weather forecast, combustible state, fire source, etc. , choose the best route to patrol. The United States and Canada used computers to choose the best route. The general patrol time should be arranged between 10 morning and 4 pm. When the fire risk level is high, patrol 1 time every day, sometimes 2-3 times a day. Pilot preparation before take-off mainly depends on wind speed and direction, which determines the flight time and course of each route. According to the specific situation of this patrol flight, the observer calculates the refueling amount and load capacity of the aircraft. Check the pilot instrument and radio station before taking off to obtain the frequency and password of the nearby radio navigation station. Observers should check the equipment and tools needed to complete the patrol flight.

air patrol

Although the United States and Canada have used Doppler navigation radar and forest fire infrared scanning camera on some patrol aircraft, the most basic navigation methods and tools are still widely used. In order to increase the observation time in the air, the plane can fly in a 360-degree rotation periodically, and the observer must always look out of the plane window. When observing, it is necessary to distinguish smoke from haze and fog. : ① Smoke: The smoke generated after grassland or forest fire moves with the wind, and the plane can smell the smoke when passing by. (2) Haze: Turbidity caused by a lot of fine dust and impurities in the air. Generally, it is thick before and after sunset, and sometimes it exists at a certain height in the air, which is called haze layer. ③ Fog: When the water vapor near the ground reaches saturation and freezes when it is cold, tiny water droplets floating in the air appear white deposits, which mostly occur at night when there are few clouds and little wind, or the next morning when it turns fine after rain. The symptoms of the fire are: on a windless day, there is a high smoke on the ground; There is a white cloud hanging horizontally in the air without Yun Tiankong, and there is smoke below to connect the ground; When the wind is strong, the visibility is not bad. Suddenly, there is a smog layer in the air, and the plane smells the burning smell of vegetation. In any of the above cases, a fire may occur. Once the fire is found, we must first know the position of the plane accurately and mark the direction of smoke transfer on the obvious identifiable features. Observers should record the time and process from landmark to fire. If several places smoke at the same time, observers should pay attention to those fires that may have serious consequences.

Determine the fire location

When determining the location of the fire in the air, it must be related to the local landmarks. The specific method is to use the map to search from far to near and from both sides to the front according to the position of the plane, first find out the obvious landmarks, and finally determine the fire location according to its relative position or azimuth distance, usually expressed by latitude and longitude. If the landmark is far away from the fire and it is difficult to determine, the direction finding method can be used, that is, the plane enters from the direction where the known landmark is aimed at the fire, records the compass heading, corrects the local magnetic declination, and obtains the true heading. Then fly to another known landmark, aim at the landmark and fly in the direction of fire, and find out the second true course, so that the location of fire can be determined by the intersection method on the map.

Determine the fire area

The following methods can be adopted: ① Visual inspection method: mainly used in small fire sites (generally below 100 hectares). This method mainly depends on practical experience, and observers should master the observation of this area at different flight altitudes. (2) Topographic mapping method: used for the calculation of large-scale fire. Mainly according to the relationship between the location of the fire and the location of landmarks around the fire, draw the fire on the map, measure the distance, and calculate the area according to the scale. ③ Calculation method: When the fire area is large and there is no detailed map, the length and width of the fire can be calculated according to the shape of the fire, using the flight speed of the plane and the flight time passing through the fire, that is, the area can be calculated. If higher accuracy is needed, in order to reduce the influence of wind, the method of flying twice in the opposite direction and averaging can be adopted.

Distinguish fire types

Seen from the air, the surface fire is irregularly extended and the smoke is light gray. From the height of 600 meters, you can't see the flame generally, and sometimes you can only see a small amount of flame. The characteristic of crown fire is that it is easy to find the burning flame on the trunk and crown from the air. The fire lasted for a long time and the smoke was black. Underground fire is similar to surface fire with low intensity. The shape of the fire is not as long as the surface fire and there is less smoke. Generally, smoke only comes from the surrounding fire line, and no flames can be seen from the plane. In order to observe the fire site and its surrounding environment carefully, and judge the direction and speed of fire spread, the composition of burning forest and vegetation status, topographic characteristics, rivers, roads, etc. The flying height of the plane should be reduced to about 200 meters, and the helicopter can be reduced to 100 meters.

Ground-air contact

Commonly used methods are: ① radio communication: generally used are: short-wave or ultra-short-wave radio installed on the plane, which can talk and report; The aerial broadcaster installed on the plane, including small semiconductor amplifier, loudspeaker and anti-jamming throat microphone, can be used to inform the fire found on the ground. A radio director was also used. The plane dropped a special transmitter, and the ground fire brigade was equipped with a receiver to receive the signal from this transmitter, so as to determine the fire location. (2) Air-dropped fire report: the observers put the fire report into a fire report bag or tube and air-dropped it to a nearby fire report receiving station or relevant departments. In addition, you can also use ground-to-air symbols, and the signal cloth made of 2× 2m or 4× 4m cloth with one side white and one side red can be folded into different shapes according to the specified "air-to-air communication symbol" to send necessary signals to the aircraft. If there is no signal cloth, use signal flares of various colors to ignite the accumulated smoke. Canada also uses paper strips to mark the location of fires. A roll of paper with a length of125m and a width of10cm was thrown from the engine room. The note will be dragged out in the direction of the flight path and landed on the target. This method can be used to locate the fire, point out the direction and road near the fire, mark the heliport and so on. The United States and Canada also use aircraft to send fire images directly to the ground fire department.

The disadvantage of air patrol observation is that the time for aircraft to observe any point is limited. In order to further improve the efficiency of aerial observation and detection of forest fires, the following measures should be taken: (1) to improve the accuracy of fire risk forecast; Choose the best route by computer; Using new instruments and methods for forest fire detection, fire area mapping and fire spread; Use night flight equipment for night patrol and so on.