Passive Measures

For a logistic convoy without significant firepower, passive measures are most effective. The key here is to prevent attacks by hostile aircraft. Dispersion is the key for air defense. The formation used by the convoy is a type of passive defense. The convoy commander must decide whether to use an open, closed, or infiltration column. Distance between vehicles must be flexible. It should vary from time to time during a march. Factors influencing selection of the best vehicle distance include the following:

Mission Cover and concealment along the route Length of the road march Type of road surface Types of vehicles route markers are needed. The close column is Nature of cargo generally used at night because air attack threats are less likely. It is also used over poorly marked routes when Enemy threat (ground or air) visual contact between vehicles is essential and in areas Presence of defense support where hostile action is not imminent. Seabees found Small-arms potential this formation to be a success in crowds during Operation Restore Hope in Somalia, Africa. The close The following are types of formation a convoy commander may choose for passive air defense:

1. Close Column. Each vehicle follows the vehicle ahead at a distance sufficient to ensure against collision. The gap specified is dependent upon road conditions, weather conditions, terrain, and convoy security requirements. Close column formation eases column control and intracolumn communications. During daylight hours, fewer guides, traffic escorts, and column prevented crowds from coming between the convoy and disrupting the movement of the convoy.

2. Open Column. In open column formations distances between vehicles are increased to enhance dispersion. This formation offers an advantage in that fewer vehicles are likely to be damaged from air-delivered rockets, cannons, or cluster bomb units. An open column increases the degree of passive protection against hostile observation and attack. It

TYPE WHEN DENSITY SPEED ADVANTAGES DISADVANTAGES FORMATION USED PER MILE/ KM mi/ h/ km/ h Close Night, poorly 67/ 40 10/ 16 Full traffic capacity of road Quick dispersion is marked routes, or can be used. Control is difficult. The column is in congested areas. better. Fewer guides, easily detected. May cause escorts, and route markers congestion at point of are needed. arrival. Requires careful scheduling and control to avoid blocking at intersections. Causes driver fatigue. Open Daylight 20/ 12 15/ 24 Less chance of enemy Command and control are observation or attack. difficult. Proper vehicle

Cargo moves faster. Driver spacing is hard to keep. fatigue is reduced. Fewer accidents, very flexible. Infiltration Daylight, con-10 or less per Various Provides maximum More time required to gested areas. hour security and deception. complete the move. Heavy traffic High speeds are possible. Column control is nearly crosses route. Other traffic has little impossible. Drivers can

effect on individual trucks. get lost. Specific details Does not hinder cross must be provided each traffic. d river. Maintenance, refueling, and messing are difficult to arrange. Vehicles may bunch up, causing close columns to form. Requires experienced drivers. Orders are not easily changed. The unit cannot be redeployed as a unit until the last vehicle arrives at destination.

Figure 5-5.- Types of column formation. permits greater highway speeds with safety and provides for greater flexibility in highway use. However, open columns make control more difficult for the convoy commander when it is necessary to give orders to stop, to continue, to disperse and seek concealment, or to engage aircraft. Moreover, the column is more likely to be attacked since it is exposed for a longer period of time. If attacked, its defense is less effective because small-arms fire is less concentrated.

3. Infiltration. In infiltration formations, vehicles are dispatched as follows:

a. Individually b. In small groups c. At irregular intervals d At a rate that minimizes changes in the average traffic density and prevents massing of vehicles

Average distance between vehicles and groups is decided by the rate at which vehicles are dispatched. Deception is provided by intermingling various types of vehicles and by permitting passing within the column. Infiltration may provide the best passive defense against hostile observation and attack; however, it provides the least active defense capability if individual or small groups of vehicles are attacked. This method permits individual vehicles to travel at high speeds and cause less cross traffic interference. It permits use of a route on which heavy traffic normally precludes the entire unit moving at one time (fig. 5-5).