Grays Point Fire, 9 January 1983

9 Jan 1983 1600h GRAYS POINT New South Wales

Heathcote Tanker 81 was a 1964 Bedford RLHC 4x4 petrol, (without high sides, charged lines, crew haven, fixed sprinklers or window screens), essentially similar to the Headquarters 81 Tanker destroyed in the same area 3 years before. The tanker and its 10 crew was one of a number of vehicles engaged in fire suppression in bushland on "Anana Hill". All the vehicles were ordered clear as changing conditions made the hill dangerous. The crew of Heathcote 81 apparently did not appreciate the danger and were too slow to depart, and found their only exit blocked by fire. The tanker reversed back up the track away from the fire then stopped . At about the same time, a civilian on foot was spotted further up the hill and 2 crew were despatched to bring her back to the tanker. She declined to be rescued and was instead accompanied safely off the hill by one of the crew. The other man returned to the tanker. The tanker crew then lit a self defense back burn, although this apparently flared up and did not assist them. A few minutes later, the tankers engine stalled and could not be restarted. This however did not cause the burnover as the vehicle was already trapped . It was then overun by fire whilst parked on the firetrack. All of the crew sheltered outside of the truck, initially behind the front wheel, and then in a huddle in the middle of the road. Three of the crew were fatally burned, and the other 6 seriously. No attempts were made to operate hose lines for protection. The drivers cabin was too small to hold the whole crew, but survived the burnover with superficial scorching and could have provided a refuge for some.

 

The Dead-Man Zone-A Neglected Area of Firefighter Safety.


The fire started in the Royal National Park, south of Sydney, adjacent to the suburbs of Gymea Bay and Grays Point.

The fire started at 0915 hours in heathland and open woodland which had not been burnt for more than 15 years and was estimated to carry a fine fuel load of 16.5 t ha (Shanahan 1984).

The topography was a flat sandstone plateau deeply dissected by several small creeks.
The fire spread slowly in the first three hours and was held up by the lee nape into a creek line. Shortly after 1230 hours the fire crossed Temptation Creek, then between 1300 and 1315 hours burnt rapidly at around 2400 m/h, after which it was held up again by the steep lee slope into the Hacking River (Figure 1).

Grays Point School 9 January 1983
Photo B Rose

The weather conditions recorded at Mascot airport, 10 km north, at 1300 hours were: temperature 38°C, relative humidity 17%, wind speed 37 kph from a direction of 320°. This gave a Forest Fire Danger Index (FFDI) of 57, an Extreme fire danger rating (Colquhoun 1983).

At 1400 hours, a helicopter reconnaissance revealed that the eastern flank of the fire was burning slowly against the wind (the wind direction at Mascot had veered to 350°) and a light shower of rain had partially extinguished the fire edge. In anticipation of a southwesterly change later in the day, a decision was made to hold the fire on Greenhaven Road (also referred to as Angle Road).

At 1549 hours, four bushfire brigade tankers were dispatched onto the fire trail which rose in a series of steep grades onto Anana Hill (Wilson 1985). At 1610 hours, the wind direction shifted to 300°.

The fire danger was still Extreme (temperature 41°C, relative humidity 13%, wind speed 35 km h’( FFDI 68).

This wind shift was not the forecast frontal change and at 1618 hours the Sector Boss recognized the danger of the situation and ordered the evacuation of Anana Hill. By 1624 hours, three tankers had cleared the area but the crew of the Heathcote tanker was slow to respond. At 1626 hours, when the Heathcote tanker started to leave, a tongue of fire had crossed the southern end of the fire trail, preventing their escape. The tanker reversed to a small clearing on Anana Hill and was over-run by fire about 12 minutes later (Wilson 1985). We do not pursue the tactical decision to place crews on this trail in the first place, but examine some of the factors that may have lead to the danger being perceived so late, thus limiting the time and space available for evacuation once the wind direction switched to 300°.

The shower of rain before 1400 hours that partially extinguished the fire edge certainly gave a window of opportunity for direct suppression of the eastern flank if crews had been equipped to run out a hose-lay and were in a position to act immediately.
However, by 1600 hours, the moisture from the rain shower had largely evaporated and the potential for rapid head fire spread had returned. Up until this time, the flank of the fire immediately west of Anana Hill had been burning slowly down-slope towards a small creek and the rocky terrain on the lee slope probably broke the continuity of the flank fire. This reduced fire behavior may have given the impression that the fire was still being affected by the rain. The distance from the creek line to Anana Hill is 180 m on a slope of 15 - 25 degress. At the rate of spread observed at 1300 hours the fire would have taken 4 1/2 minutes to travel from the creek line to Anana Hill but, when the rate of spread is corrected for slope of 20°, this time would reduce to a little over one minute. Because the fire crossed the creek line in a series of narrow tongues, the head fire probably did not teach its full potential rate of spread up the slope (given this potential rate of spread once the fire crossed the creek line, there really was only time for the crews to abandon the hoses and leave. The height of the shrubs adjacent to the trail was 2-3 m and there was little indication that the ground sloped steeply to the west a few metres from the trail. The shift in wind direction was only 20° so it may not have been immediately obvious to the crews, particularly if they had started burning out.

In this situation, perhaps the only indication of the changed conditions would be the increase in smoke volume overhead.

©Originally published as: Cheney, NP, Gould, IS, and McCaw, L. (2001) The Dead-Man Zone-A neglected area of firefighter safety.

Memorial to those Heathcote & Headquarters Members who have died while fire fighting.