The reference for this technique for “Crossing a Linear Danger Area” can be found on page 6-9 and A-8 of your Ranger Handbook.
A Line Danger Area (LDA) is a danger area that has a long axis where the enemy can concentrate their fires on your unit as you cross it. Examples of LDAs are roads, trails, rivers, or any type of natural or man-made feature where your unit may be observed crossing. Think of a LDA as a fatal funnel.
Let me introduce you to the “20 Board” above. On the right hand side of my board, there are administrative notes to help you follow along. In the center, there is a 12-man Infantry squad crossing a LDA. Since the squad planned to cross at this point, there is a given grid location and terrain feature for the crossing. At the lower portion of the board there is the Near Side Rally Point (NSRP) for the tentatively planned crossing point with a corresponding Grid Location (GL) and Terrain Feature (TF). At the top center portion of the board, you will see the Far Side Rally Point (FSRP). Again, the FSRP has a GL and TF.
If the squad comes upon an unplanned/ unknown LDA, the Rally Points can simply be “floating” Rally Points. This means that the far side rally point is 300 meters from the LDA on the mission azimuth. The near side rally point is 300 meters from the LDA on a back azimuth.
On the left side of the board, arrows indicate the most probable direction of enemy attack as this squad crosses the LDA.
Notice that the board is color-coded but not personalized. Color coded refers to the board displaying the lead team in BLUE, the HQ element in YELLOW, and the trail team in GREEN. While at Ranger School and Sapper Leader Course, you will color-code and personalize all of your boards. For example, if I were the Squad Leader (SL), there would be a line next to the SL circle with my name on it. Note that if there is a LDA on your route, you will need to name the danger area on your boards. You can either use the name of the road from the map or if it has no name label it “no name road” or “no name trail” on your boards.
1. Route Planning Considerations
While planning routes and traveling during your mission, you must avoid LDA as much as possible. Crossing a LDA greatly increases the chances of observation and/or engagement by enemy forces. That being said, bypassing all LDAs during your missions is almost impossible. At some point, you will have to cross a LDA. You should plan and coordinate for indirect fires to support your crossing of all known LDAs.
When crossing a LDA, your element must maintain security. Failure to maintain security while crossing a LDA could cost your soldiers their lives. The importance of conducting a detailed map reconnaissance of your routes and taking the time to fully think through how your element will negotiate any LDA that you come across during movement cannot be overstated.
With this in mind, let’s discuss how to negotiate LDAs.
2. KNOWN VERSUS UNKNOWN
You want to avoid Danger Areas while patrolling. LDAs can fall into two categories: known and unknown. A known LDA is one that is depicted on the map. Your element identifies a known LDA during planning and determines the element has to cross it either going to or coming from the OBJ. An unknown LDA is not depicted on the map or is one that the tactical situation demands crossing. With known LDAs, you need to decide on a predetermined near and far side rally point and a predetermined crossing point. These rally points have a 6-digit grid, terrain feature, and a direction and distance from the crossing point. The leaders must disseminate all of this information to everyone going on that patrol. These locations are decided upon during your route planning. For unknown LDAs your RP can be floating rally points. For example, your NSRP will be 300 meters on a back azimuth from the crossing point. The FSRP will be 300 M on azimuth from the crossing point.
3. Rally Point Characteristics
When determining the near and far side rally points, you will look for the five characteristics of a good rally point. An easy way to remember these characteristics is to remember “Easy, Away, Away, Provides, Provides”. Rally points are:
- Easily defendable for a short period of time.
- Away from natural lines of drift.
- Away from high-speed avenues of approach.
- Provides good cover and concealment from both ground and air.
- Provides little or no tactical value to the enemy.
4. Crossing Points
When looking for a crossing point, look for a location that provides the least chance of being detected by the enemy. For a known LDA, the crossing point has a 6-digit grid and a terrain feature. For an unknown LDA your crossing point must be a suitable site close to where your direction of travel crosses the LDA.
Good places to cross are at:
- A bend in the road.
- Low-lying areas.
- The military crest of a hill.
- Areas that provide cover and concealment close to the LDA on the near and far side.
Poor places to cross are at:
- Road/Trail Intersections.
- At the long axis of a road.
- Hill Tops.
- Any area that does not provide cover and concealment for your element as they cross the LDA.
The ideal crossing point would be in the low ground, at the bend of the LDA, with cover and concealment close to the edge of the LDA on the near and far side.
There are two types of LDAs; they are either Natural or Man-made.
5. Man-made LDA
Examples of man-made LDAs are:
- Roads
- Vehicle or Foot Trails
- Railroad Tracks
- Clear cut areas for power/telephone lines
A key thing to remember is that if man made it, then men will use it.
6. Natural LDA
Examples of Natural LDAs are:
- Streams/creeks/rivers
- Erosion ditches
- Game trails (Large game trails)
7. Active/Inactive
LDAs can be characterized as either Active or Inactive. When conducting a recon of an LDA before crossing it you want to determine if it is active or inactive. An active LDA will have signs of recent use, things such as:
- Foot or vehicle tracks
- Trash/debris
- Broken vegetation/disturbed dirt/gravel
Remember that a paved road will probably not show signs of recent activity.
An inactive LDA may not warrant emplacing security as your element crosses, however, elements will still maintain security as they cross the inactive LDA.
8. Actions at an LDA
This is an example of how to cross a LDA:
9. Halt
Once the lead TL sees a potential LDA, he gives the hand and arm signal during good visibility (GV) or command for halt during limited visibility (LV) and danger area (examples below), the squad halts, and establishes a 360-degree perimeter in the Short Halt Posture.
-"Halt" Hand and Arm Signal 
-"Danger Area" Hand and Arm Signal
10. 360 degree security
The SL does a quick visual check to ensure that 360-degree security is established then moves his way up to the lead TL's position.
The TL tells the SL why he has halted, in this case there is a potential LDA to the front of the squad.
11. SLLS/Pinpoint
The SL has the squad conduct SLLS to check for any enemy activity in and around the area, particularly for any foot or vehicle traffic on the LDA.
The SL and TLs then pinpoint their current location on the map. Soldiers must always remain aware of their current location on the map. Taking the time to pinpoint the current location on the map prevents the patrol from drifting off the planned route and running into an unplanned LDA. If the patrol is relatively close to the OBJ and plan to conduct an ambush, then they will want to take the time to ensure they are not about to cross the OBJ.
Knowing the location and terrain, allows the patrol to make a sound tactical decision on how to negotiate a LDA.
12. RECON LDA
The lead TL and SL move forward using available cover and concealment, to recon the potential LDA. The SL and lead TL must not expose their movement to the LDA; they must utilize available cover and concealment to avoid detection. After they get eyes on and determine that it is in fact a LDA the SL needs to determine how the squad is going to cross it.
13. Assess LDA
When the SL and lead TL are conducting the recon of the LDA the SL needs to determine a couple things to assist him in deciding on the threat the LDA poses to his Squad. They are:
- Is the LDA Man-made or natural? Remember if it is made by man, men use it.
- Is it a known or unknown LDA? If it is a known LDA that the Squad plans on crossing, is the squad at the correct crossing point? If it is an unknown LDA, did the squad drift off of their planned route?
- Is the LDA active or inactive? If it is active then flank security has to be emplaced and the threat of compromise is much higher as the squad crosses. If it is inactive the SL may decide to cross the LDA without emplacing flank security elements.
14. ID Crossing Point and Security Locations
Additionally, the SL needs to determine the following while he and the lead TL are conducting a recon of the LDA:
- Identifying a crossing point. Whether it is a known or unknown LDA the SL must find a suitable crossing point. The SL also must look at the far side of the LDA to ensure that it provides adequate cover and concealment and unrestrictive terrain so the squad can continue movement after crossing the LDA. Remember, an ideal crossing point is a bend of a road in the low ground with cover and concealment as close as possible on the near and far side of the LDA.
- Identify a suitable location for the left and right flank security elements. The SL wants to find a location where the flank security personnel can see down the long axis of the road to provide early warning. The flank security position MUST be in line of sight with the crossing point. The flank security positions must also provide cover and concealment for the personnel on flank security to hide behind if enemy elements move down the LDA.
After the SL completes his recon of the LDA, he and the lead TL return to the squad’s security halt. At the security halt, the SL briefs the lead TL and the trail TL on how the squad will cross the LDA. The SL tells the trail TL to bring his team forward. While the trail TL moves his men, the SL issues tasks, conditions and standards to the lead TL for clearing the far side of the LDA. It sounds something like this.
"On my signal, your team crosses and clears the far side. Move far enough in to allow the entire squad to cross the LDA and not be seen from the road. This is normally a 50m by 50m area. Look for signs of enemy activity and ensure that the squad can continue movement through the terrain. If it is not suitable, move your team back to the near side. If it is suitable, continue clearing and call me via FM. If the radio does not work, I want you to halt your element and send your last man back to signal when it is clear using either a thumbs up during GV or during LV use either IR flash or compass vertical answered by compass horizontal. When you have finished briefing your men, return to the apex of your fire team so that I know that you are ready to cross”. Once the Lead TL understands the SL’s instructions, he moves out to brief his team.
After the SL briefs the lead TL, he links up with the trail TL. By this time, the trail TL should have brought his team forward to the SL’s location. Also, at this time the personnel in the HQ element pull rear security for the squad.
16. EMPLACE FLANK SECURITY
To emplace the left and right flank security, the SL has several options. He can:
- Physically emplace them himself.
- Have the trail TL physically emplace them.
- Have the trail TL emplace one team and he physically emplaces the other.
- Point out where he wants the flank security and they can emplace themselves.
The SL decides which option he will choose based on the competency of the Trail Team Leader and the amount of trust the SL has in them. The SL also considers whether it is good or limited visibility, the terrain, the vegetation, and how much time they have before they need to be at their OBJ.
17. Point out crossing point
It is important that the SL points out the crossing point to the personnel on the flank security elements. The flank security teams MUST be able to see the crossing point from their security position.
18. Trail team with 4/5 personnel
If the trail team only has four personnel, the trail TL is on flank security on the side that the SL determines to be the most probable direction of enemy travel. Since on my board enemy contact is higher from the left side, the trail TL would be on left flank security.
If the trail team has five personnel or more, the trail TL can find cover and concealment on the near side of the LDA at the crossing point to assist in the movement of the squad across the LDA.
19. Most casualty producing weapons point out
The left and right flank security elements only consist of two personnel. The soldier with the most casualty producing weapon pulls security facing away from the crossing point. Also, the team’s most casualty producing weapon, normally the M249 SAW, is on flank security on the side that the SL determines as the most probable direction of enemy travel. Again, using the example on the 20 board, the SL has determined the enemy’s most likely avenue of approach is from the left side of the crossing point. Therefore, the M249 SAW would be placed on the left flank security position facing away from the crossing point.
After the M249 SAW, a team’s next most casualty producing weapon is the M203. This weapon should be on the opposite flank security as the M249. In the example on my board, the M203 would be placed on the right flank security position, facing away from the crossing point.
20. Emplace security in SHP
The personnel at the left and right flank security positions are in the Short Halt Posture. The soldier with the most casualty producing weapon faces away from the crossing point and the other soldier at the security position faces back towards the crossing point. During periods of LV the soldier facing the crossing point takes his compass out, opens it up and places it at chest level with the face of the compass exposed to the crossing point so that the personnel at the crossing point can see the green glow of the compass.
Both soldiers in the security positions have their feet touching so they can use the tap code as a non-verbal means to alert one another of the enemy’s approach.
The following are the signals for the tap code. A soldier gives one tap to his buddy if everything is okay. If everything is okay with the other soldier, he responds with one tap. A soldier gives two taps if he sees or hears something. Three taps means that a soldier sees or hears the enemy and the element needs to take action. In this case, the flank security element needs to get into the prone position IMMEDIATELY.
21. SQUAD CROSSES THE LDA
Once the SL approves the position of the flank security elements, he gives the lead TL the hand and arm signal (GV) or command (LV) to move.
After receiving the signal to move, the lead TL moves his team forward to the last covered and concealed position before the LDA. There, the lead TL halts and looks to his left and right to ensure that he can see the men on the left and right flank security in the short halt posture. During LV he can see the green glow from the compasses that the men facing the crossing point have at chest level. If the lead TL cannot see the left and right flank security personnel, or he sees that they are in the prone, he does not cross the LDA.
Again, if a security element sees or hears possible enemy traffic on the LDA they get into the prone position to signal the personnel at the crossing point that it is not safe to cross.
Once the lead TL sees that the flank security personnel are in the short halt posture, signifying that it is safe to cross, he moves his team across the LDA. For this movement, the team moves quickly without running and maintains a wedge formation to clear the far side.
22. Lead team clears far side
The lead team clears the far side of the LDA in accordance with the SL’s tasks, conditions and standards. Again, the cleared area should be at least large enough for the entire squad to occupy, which is generally about 50 meters by 50 meters. If the far side is clear, the lead TL informs the SL that the far side is clear using radio or the prearranged signal.
If the far side is not clear, the lead TL moves his entire team back across the LDA and informs the SL of the situation.
23. HQ follows, trail team breaks down security and follows
Meanwhile, the SL moves the HQ element up to the crossing point and awaits the “all clear” signal from the lead team. Once the SL gets the signal that the far side is clear, he moves the HQ element across the LDA. Again, the element moves in a team wedge formation and links up with the lead team.
The trail TL monitors the flow of the Squad across the LDA. Once the SL has the HQ element on the far side, he gives the trail TL the signal to cross. The SL can send the signal via FM, hand and arm signal, or any prearranged signal the SL deems necessary. Nine times out of ten, the trail TL can visually recognize when the HQ element is on the far side.
When the trail TL receives the signal to move across, he has to recover his flank security teams. He can do this by several means. During GV, he can simply use H&A signals to move his men across. During LV or when moving through restrictive terrain, the trail TL may have to collapse his flank security teams back into the crossing point in order to maintain control.
Either way, the trail TL needs to ensure that his security teams maintain security as they cross the LDA.
During periods of GV, when the security teams get the signal to cross, each security team crosses as a buddy team and moves straight across the LDA. The man facing away from the crossing point stays in position and pulls security as the other man crosses the LDA. Once the first man reaches the far side, he takes up a security position and pulls security facing away from the crossing point. After this Ranger on the far side is in a security position, his buddy crosses the LDA. Once all members of the security teams are across the LDA, the trail team returns to the fire team wedge formation.
During periods of LV, the security teams collapse into the crossing point from their flank positions. The security team members still pull security and cross by buddy team in the same manner as described.
Once the trail TL has accountability of his team on the far side he lets the SL know his team is across the LDA.
After the entire squad crosses the LDA, they get back into their FOOM (Formations and Order of Movement) and continue with the mission. (Learn about FOOM here)
24. ACTIONS ON ENEMY CONTACT
As always, when contact is made with the enemy, the key to success is to maintain control of your element. Contact can be made anywhere around a LDA.
If contact is made while crossing a LDA and the SL is in control of his Squad, he determines to either conduct a Squad Attack (Learn about Squad Attack here) or Break Contact (Learn about Break Contact here).
If the squad is in contact and the SL loses control of his squad, then the SL, if possible, calls out which RP best facilitates the squad's survival and mission completion. An example situation where the SL may lose control is contact with an overwhelming enemy force. Once the SL calls out the RP, every squad member echoes the command. The squad members then break contact by buddy teams and E&E to the designated RP. Once at the RP, the elements conduct rally point procedures. While soldiers break contact and move towards the RP, they must ensure that they use all available cover and concealment and get away from the LDA as quickly as possible.
The worst case scenario is if the squad makes contact while crossing the LDA by an overwhelming force and the LDA cuts the squad in two. The example you see on my board shows that the lead team is on the far side of the LDA and the HQ element and the trail team are on the near side. A couple of T-72s come down the road and begin engaging the squad.
Of course, all elements break contact away from the LDA and move to the rally point on their side of the road. The lead team moves to the FSRP. The HQ element and trail team moved to the NSRP. Both elements conduct rally point procedures at their respective rally points and attempt to establish communications with each other.
If communications can be established, the SL gives instructions to the personnel at the other rally point and the squad conducts a link up wherever the SL designates.
If the personnel at the FSRP and the NSRP are unable to establish communications with each other, then as a general rule of thumb, the RP that the SL is at becomes the squad’s active RP. Therefore, the element that is not at the squad’s active RP must find another location to cross the LDA and link up with the remainder of the squad at the squad’s active RP. It is easier for the smaller element to E&E (Escape and Evade) across the LDA without being compromised.
This was a summary of how you will be expected to cross linear danger areas at Ranger and Sapper School.
You can continue learning by reading about Conduct a Link-up.
Conduct a Link-up can be found here.