English articles

Searching in Smoke

Article by Paul Grimwood

(Archived from Fog Attack 1992)
These were how things were done some 40 years ago!

“I do not intend to discuss in any great detail the various search ‘patterns’ and techniques used to complete a ‘blind’ search in thick smoke and darkness. The reader will already be (I presume) well practised in such procedures and one needs only to refer to a basic training manual to glean such information. However, I wish to touch upon one or two points that are occasionally seen to hamper search and
rescue operations.

In general, a ‘walking’ search pattern is considered most effective where visibility and smoke conditions are light to moderate; where there is no possibility of overlooking an incapacitated occupant; and the crew is able to advance in safety. Under such circumstances it is perfectly feasible to expect open areas to be searched with extreme speed and research findings have indicated that a ‘search-rate’ of
4.000 sq ft/min. (368 sq m/min.) is possible.

To simulate search and rescue (S&R) operations under more severe conditions the Dallas Fire Department carried out some research where firefighters, with sanded SCBA visors to obscure vision, adopted a ‘crawling’ search pattern. In an open area, under simulated conditions of moderate to heavy smoke, the crawling firefighters were able to complete their search at a rate of 227 sq ft/min. (21 sq m/min). However, under the same conditions, the search-rate was reduced further still when working in a compartmented area, where a rate of 163 sq ft/min.(15 sq m/min.) was indicated.

These are interesting findings and through ‘real’ fire experience I can relate to them directly. It is most certain that ‘real’ fire search-rates will decrease even further and I would suggest that for compartmented areas a more reliable estimate would be 100 sq ft/min. (rounded to 10 sq m/min. for ease of calculation).

Having reached this stage we are now in a position to create a reliable formula that can be used to estimate the on-scene staffing requirements for any particular S&R operation. For example: If a hotel, consisting of five storeys, measured 100×30 ft (totalling 3.000 sq ft on each floor level) and a fire at the second level had led to severe smoke logging of the 3rd, 4th and 5th levels, how many firefighters would be
required to complete a search of these upper levels within a ten minute time scale?

Solution: By totalling the floor area to be searched (9,000 sq ft) and dividing this by the standard ‘search-rate’ of 100 sq ft/min., we are left with 90. This means it would take one search team 90 minutes to search the three levels, if heavily
smoke-logged. Now, by dividing 90 by the ‘target time’ (in this case the target time is 10 minutes) we are left with the figure nine. This tells us that it will take nine search teams
about 10 minutes to complete the search of upper floors (3, 4 and 5) in the hotel. NB: Where this method is used under metrication, to simplify matters for fire-ground purposes a rough estimate of manpower requirements can be achieved by using a standard ‘search-rate’ figure of 10 sq m/min., although a figure of9sq m/min. would yield a more exact answer.
The ideal size for search teams under such circumstances would consist of two firefighters. Where large open areas are to be traversed for search purposes, or where teams are advancing a hose-line into a structure, additional firefighters may be required to form a team. However, the case in question places a demand for 18 firefighters to be assigned in nine units to complete the task within the time-scale

Such a demand for staffing, on the initial response, would place a heavy burden on the fire force and stretch their eapability to the limit. Indeed, as I explained in Chapter 1, many forces would be unable to cope with such a demand
and S&R times would have to be increased, reducing the survival chances of trapped occupants. It is here that the ‘Expanded Response System’, as practised in Phoenix and Seattle, USA, would achieve its greatest effect. It should be noted that S&R times (10 minutes in this case) do not actually start until search teams reach the affected floors.

Case History:
Hotel Fire – West London, UK

Prior to the mid-1970s, when the UK’s stringent life safety codes for hotels began to take effect, this west-end central area of London was renowned for its particularly bad fire record concerning such occupancies. However, even with current legislation enforcing the provision of fire alarms, adequate escape routes for occupants, and restricting the
materials used for internal finish, a major hotel blaze is still not totally impossible.

The particular incident in question was typical of the modern-day fire that serves to demonstrate the effectiveness of an in-built fire protection factor. However, when elements of workmanship deteriorate, or fire doors are left open, the fire
force is faced with an immense problem in this type of structure, particularly if the fire occurs during the early hours.
As firefighters arrived on scene at this particular incident just after midnight the hotel of six floors, measuring 50×30 ft, was partially alight at the second level. The upper levels (3 to 6) were charged with variable amounts of moderate to heavy
smoke, and an unknown number of occupants were believed involved. It was fortunate that a second stairway remained passable throughout the fire and the entire building occupancy had been able to use this to escape to safety, prior to the
firefighters arriving on scene. However, the incident commander could not be assured of this at the outset and a massive S&R operation ensued.

Several important lessons were learned, and reinforced during these operations;

(a) The S&R teams consisted of three firefighters. In total, three teams (9 firefighters) were despatched to the upper levels to complete the task.
(b) On entering the structure, the teams had not been properly briefed as to their objectives. They had simply been told that persons were believed trapped at upper levels and a search was to be made.
(c) There was no method in use of indicating areas/rooms that had been searched to firefighters on the upper levels.
(d) In effect, what resulted was a totally inefficient search pattern that wasted resources and stretched the target time. The entire operation took nine firefighters over 30 minutes to complete. Initially, the teams would have been better deployed in two-man units. The S&R formula tells us that the 6,000 sq ft area (four floors) would have taken four two-man teams about 15 minutes to complete the task. Ideally, each team could have taken a floor to themselves. However, without adequate instructions, the three-man units found themselves wasting valuable time, searching areas that had already been checked by other teams. If a door marking system had been utilised this would not have happened. Additionally, firefighters experienced great difficulty in keeping together as teams passed each other and searched rooms off of the confined corridors”.

Formula –

Area to search (A) / Search rate (SR) = minutes

Minutes / Target Time (TT) = Search teams

A = sq.ft or sq.m
SR = 100 sq.ft/min or 10 sq.m/min (9 is exact)