Why would a department use a 125-foot aerial ladder to rescue people from a third-story apartment window? Why would another department use a 114-foot articulating-boom platform to deliver a master stream onto the roof of a 4-story hotel? The answer is that many departments are finding situations where the combination of large vertical and horizontal distances, often coupled with intervening obstacles, require maximum reach from very long aerials.

In the first example, the department protected an area of older homes that had been converted into apartments. The buildings were situated on narrow lots set back from the street with large front lawns. There was no access from the rear. To reach the top-floor apartments at the back of the building, the department had to operate from the street and fully extend the aerial ladder between buildings at a low angle.

In the second example, the hotel was located between two other buildings and had a swimming pool and a sprawling one-story restaurant located in the front. Again, there was no access to the building from the rear. To perform any firefighting or rescue operations at the hotel, the department had to use the articulating-boom platform to reach up and over the intervening restaurant and pool.

These are just two of many examples why departments may need long aerials. Other examples might include protection of resorts or amusement parks, where access to the grounds is limited, as well as operations involving high-rise retirement homes or hospitals. Even departments with nothing taller than a new multi-story motel or a development of townhouses on the edge of town may find that the combination of distances and obstacles requires a much longer aerial than they expected.

One way to determine the required length of an aerial is to rely on direct measurement or visual inspection. If a department already has an aerial that doesn't reach the roof of some of the newer buildings in the area, then that should provide a clear indication of how much longer the aerial needs to be.

Departments that don't have aerials or those trying to plan ahead for future needs may have to rely on calculations to determine the required aerial length. To do these calculations accurately, departments need to consider the height of each building, its setback from the street or point of nearest access, the difference in elevation between the building and the apparatus, the height of the aerial turntable, the maximum angle of elevation of the aerial and how much if at all the aerial retracts when lowered toward the horizontal. Most apparatus manufacturers can provide customers with a diagram that shows the operating envelope of an aerial at all angles to help with these calculations.

For situations where the building setback is not too great and the building and apparatus are at the same elevation, a less complicated calculation is all that is required. Take the height of the building and multiply it by itself. Then take the distance away from the building to the center of the turntable and multiply it by itself. Add the two numbers and take the square root. Most small electronic calculators can do this. The result is roughly the required length of the aerial.

For example, if the height of a building is 80 feet, and the distance away from the building to the center of the turntable is 60 feet, then the required aerial length is roughly 100 feet. Add several feet to the length if standard operating procedures require projecting the aerial over the edge of the building to provide access and visibility for crews operating on the roof. Remember to consider roof parapets when figuring the height of the building and add the width of cars parked at the curb when figuring the distance away from the building.

The Insurance Services Office evaluates fire departments based on the Fire Suppression Rating Schedule. This schedule awards points for apparatus, equipment, communications, water supply and many other factors. If a department needs one or more ladder companies, ISO will award points for the aerial device itself, as well as for annual aerial testing, ground ladders, an elevated stream device, generator and other pieces of equipment.

ISO recognizes both aerial ladders and aerial platforms on ladder companies with the provision that they must be of sufficient height to reach the roof of any building or 100 feet, whichever is less. ISO will prorate the points for aerials with insufficient reach; if a department needs a 100-foot aerial, but only has a 75-foot unit, ISO won't award full points. On the other hand, if a department needs a 125-foot aerial, but only has a 100-foot, ISO will still award full points.

The 100-foot limit has been part of the ISO rating system for many years and reflects the practical fact that departments in larger cities can't possibly be expected to have aerials that reach the roof of every tall building.

Despite the fact that departments don't get extra ISO points for aerials over 100 feet, they still will get the maximum number of points in this category. More importantly, longer aerials can provide significant advantages in many fire and rescue situations and can often make the difference between getting the job done or not. Departments can choose from several lengths and models ranging from 100 feet to 125 feet or more depending on their specific needs.