A bubble in a blizzard

A fatal ground collision between two German police helicopters teaches hard lessons in situational awareness—and situational response.

Nearly a year before a collision in billowing snow between two of its helicopters Germany’s Federal Police Flying Squadron (die Bundespolizei Fliegergruppe), made an unheeded recommendation:

Develop training for crews to avoid the dangers of a whiteout…

The recommendation emerged from the investigation of a heavy landing in January 2012 involving one of the squadron’s 17 police helicopters. The investigation discovered there was no documented procedure for a snow-induced loss of visual reference during approach or take-off—colloquially known as a ‘whiteout’. This recommendation was to be acted on or before September 2013. But nearly 12 months later, and as the winter of 2012-2013 approached, the recommendation remained dormant as the squadron busily prepared for an anti-terrorist activity.

The operation would see three helicopters carry counter-terrorist forces to the historic Olympia Stadium complex, site of the 1936 Olympic Games. The three helicopters, two AS332 Pumas and one EC155 Dauphin, were tasked to deliver anti-terrorist officers to a large sports field just outside the stadium.

The mission was relatively simple and, for the most part, well planned. It included significant discussion about the possibility of a whiteout due to recent snowfalls.

Most experienced helicopter crews know full well the severe danger of whiteout and its dirty sibling, the dust-induced ‘brownout’. The danger arises because hovering is a precisely coordinated activity completely reliant upon the accurate assessment of rates and proximities—without visual reference things quickly go bad for the crew. Think inadvertent IMC at three to 10 feet above the ground with blade tips spinning at two-thirds the speed of sound only a few more feet above. The helicopter is literally poised on a tornado of air (medium helicopters can easily create a 100 km/h downdraft). When this tornado of air encounters loose dust or snow, it disturbs them, flinging them about madly, and masking visual references required for accurate hovering. Up is no longer distinguishable from down, nor left from right, and the aircraft inevitably begins to drift rapidly and dangerously until the pilot either initiates a go-around using instruments, or ‘arrives’ on the ground.

Many crews do not successfully make the go-around transition, and as a result, blowing dust has destroyed more military helicopters in the last ten years than bullets or missiles.

According to Michael Hirschberg, executive director of the American Helicopter Society International, ‘Brownout has been a significant contributor to the losses of some 600 Americans and 400 vertical flight aircraft in the past 10 years of conflict—much deadlier than enemy actions’. In Europe, while the billowing cloud is generally white and cold rather than hot and dusty, the dangers are equally real. Most of the crews preparing to fly into the Olympia Stadium had enough hours to have experienced at least a few whiteouts in their time. And, as with many military or paramilitary crews, they were no slouches when it came to improving mission SA through contingency planning and risk management.

The crews noted from weather reports that approximately 18 cm of snow had fallen by 0700 that morning, including at least 5 cm that was fresh and likely to blow. The crews of the three helicopters discussed the possibility of a whiteout and formulated a number of controls.

They decided to use a stream, staggered landing profile to ensure each helicopter would be able to land independently of the others’ anticipated snow cloud. They directed ground police to park their vehicles with flashing blue lights behind each designated landing point. They then directed marshals to stand in front of the vehicles to provide further reference points. They refreshed themselves on what they considered to be the best type of approach to mitigate the risk of an obscured landing. In short, the possibility of a whiteout was well and truly registering in their SA bubble as they implemented what they thought were tried and true controls. However, it would soon become obvious that while SA is never less than awareness, it is certainly way more.

Planning complete, controls implemented and with police marshallers standing by, the first police helicopter, an EC 155 with the call-sign ‘Tactical 1’, approached the sports field outside the Olympia Stadium. Two Super Pumas, called ‘Tactical 2’ and ‘Tactical 3’, followed closely in staggered stream formation. Tactical 1 approached its pre-planned landing point with short verbal cues and clearances being passed by the flight engineer acting as a crewman (the police crewing model incorporated a pilot and flight engineer/crewman). As the pilot of Tactical 1 flew the approach there were three recognised profiles he could have chosen for an anticipated white-out landing.

1. A slow approach to a high hover assessing the ensuing snow cloud from above before deciding to land or go around.
2. A roll-on landing staying ahead of the snow cloud. (For a wheeled helicopter, if the landing area allowed.)
3. A moderately faster-–than-–normal approach staying ahead of the cloud as long as possible, and then terminating with zero speed/zero rate of descent, thus minimising the time hovering with low visibility.

Tactical 1, 2 and 3 were all familiar with method 1—a higher approach, waiting for the snow to clear, than either landing or going around. However, the squadron’s nearly year-old internal safety recommendation had been made because method 1 was considered inadequate in some circumstances. Additionally, initiating a rapid go-around in the event of visual loss was recognised as an imperative.’ This went unheeded.

As Tactical 1 approached to within 30 feet of the pad it was quickly enveloped in snow. Although surprised by the extent and depth of the snow cloud, the crew was able to maintain some visual reference with their marshal and land. Safely on the ground, and with their helicopter-made snowstorm still drifting across the landing zone they became, literally, front row spectators for the approach of Tactical 2. It was close behind and attempting to land on the opposite side of the pre-planned point because of the drifting snow cloud. The cockpit recording of the last words of Tactical 1’s pilot as he observes the approach of Tactical 2 best describes the imminent disaster.

‘He decelerated too soon (Er hat zu früh die Fahrt herausgenommen).’

‘Now you can see what a problem this is, one has no reference point any more (Na ja, ihr seht jetzt was das für ein Problem ist, man hat keine Referenz mehr ).’

‘He now goes backward with the machine (Er geht jetzt nach hinten mit der Maschine)’.

And a final, prophetic, observation: ‘Das ist sehr gefährlich (This is very dangerous)’.

It was. Fatally so. Tactical 2 spent at least 30 seconds drifting backward and forward in ever-deteriorating visibility before finally landing in near zero visibility.

With Tactical 2’s snow cloud still swirling about, Tactical 3 was now on short final and entering the combined snow cloud. Ironically, it was the pilot of Tactical 3 who had the most experience with blowing snow and who had insisted on more considered planning for the operation due to his concern about a whiteout. He was now dealing with the worst of it. Nonetheless, even with the evident snow cloud, Tactical 3 continued its relatively slow approach to the hover. Six months later, the official investigation concluded: ‘none of the conducted landings corresponded with the recommended landing techniques under whiteout conditions.’

Video, which can be viewed here and here, shows the result. All three helicopters, the three police vans and the three marshals are dramatically consumed by the agitated snow cloud.

A few seconds later the dreadful sounds of collision are heard as the impact between Tactical 3 and Tactical 1 produce a new type of cloud—a metallic one comprising helicopter fragments bursting missile-like out of the billowing snow. Tactical 3 has drifted sideways, and after touching the ground, gone into dynamic rollover and struck Tactical 1. The fragments, dangerously ballistic, are violently ejected out of the drifting snow striking vehicles, infrastructure and flesh before their energy is finally spent. The pilot of Tactical 1 is killed by a blade fragment; and several others, both crew and ground staff, are seriously injured.

Among the ‘usual suspects’ in the accident report there is this causal factor:

After the visual contact with the reference point was lost, the landing was not aborted immediately…

There are many technical definitions of situational awareness. Endsley’s is probably the most quoted:

‘the perception of elements in the environment within a volume of time and space, the comprehension of their meaning, and the projection of their status in the near future,’.

We pilots simply call this our ‘SA bubble’: to have a large SA bubble is a good thing, to have a small SA bubble is not.

While academics may not like this kind of ‘reductionism’, such a metaphor is a neat way to, as James Reason says, ‘convey [a] complex idea in a concise and digestible fashion…’ This is the plus of safety metaphors or models. The minus is they ‘convey complex ideas in a concise and digestible fashion’. In other words, the same property of a metaphor that makes it helpful can also make it unhelpful. In one sense, and as with most metaphors, the concept of ‘SA as a bubble’ has explanatory power, but in another sense it, ironically enough, reduces our SA about SA. The idea of SA as a bubble implies action-less awareness. Bubbles connote a sort of floating about—without the imperative for action. But as the accident at Olympia Stadium shows, SA has decisional direction and force.

The pilot of Tactical 3 in the collision-initiating aircraft had good SA about the implications of a whiteout. He had a bigger SA bubble than anyone else on the day—at least in terms of ‘the perception of elements in the environment within a volume of time and space… in the near future’. It was he who insisted on ratcheting up the risk management controls. It was he who had a large amount of flying experience in whiteout conditions and had requested the presence of marshallers who would be more easily discerned in the snow. However, when his SA bubble was clouded in by blinding snow:

… the landing was not aborted immediately.

With his companion aircraft already on the ground, the imminent arrival of dignitaries and the prospect of piloting embarrassment in front of fellow professionals, the pilot’s SA bubble provided awareness but did not provide what was needed most—conviction to act: to go around in the face of an imminent threat. In this case SA was not a bubble but a vector—a compelling vector onwards to landing no matter what. And this is the point.

Our SA is not direction– or action–less awareness. Our SA, distorted or otherwise, has direction and force. It is taking us somewhere, compelling us somewhere. Which means, as a final caution, when next we are considering the safeness (or otherwise) of our operational, organisational and cultural SA, we should ask where such SA vectors are taking us. If the answer is with the flow of negative organisational, cultural or ‘loss of face’ pressures, we would do well to remember where such vectors took Tactical 3.

Suggested reading

James Reason, The Human Contribution, Ashgate Publishing, Surrey, 2008