Friday, July 17, 2009

Loss of the Southern Cloud

Though far and wide they sought him, they found not where he fell
For the ranges held him precious, and guarded their treasure well.

" Lost" – by Banjo Patterson

In the early morning of Saturday March 21, 1931, Captain Travis Shortridge, his co-pilot and six passengers boarded their aircraft VH-UMF - the “Southern Cloud”-, for a routine commercial flight from Sydney to Melbourne. The weather was overcast, with a light northerly wind and the temperature was close to 22C. Soon after 8 am, the Avro 10 lifted off from Mascot aerodrome, climbed away to the south-west and set course for Essendon airport in Melbourne. It would not be seen again for another 27 years, and became instead, Australia’s first major civil aviation disaster.

During the late 1920’s and early 1930’s, passenger flights between Sydney Brisbane and Melbourne gradually became more common, as the public was slowly convinced that flying was safe and fast – the modern way to travel.

Australian National Airways (ANA) operated daily services between the eastern capitals using their fleet of five Avro10’s, all named in honour of Sir Charles Kingsford-Smith's legendary Southern Cross. There was the Southern Sky, Southern Star, Southern Moon, Southern Sun and Southern Cloud, all state of the art airliners manufactured by the English company Avro.

By modern day standards, the Avro 10 was a very primitive machine, although, if flown within it’s capabilities, was safe and reliable. It was powered by three ponderous Armstrong Siddeley Lynx 7 cylinder air-cooled radial engines, each generating a modest 240 horsepower. It was not a small aircraft, being 14.25 m in length, with a massive wing-span of over 21 metres, but could only carry a flight crew of two together with a maximum of eight passengers. The cruising speed was 160 kph but it had a top speed of about 185 kph and could reach an altitude of around 3400 m – not a great deal higher than Mount Kosciusko’s 2228 m.

Above: A "sister" aircraft of the "Southern Cloud" - VH-UMH was
an identical Avro 10 tri-motor. The massive undercarriage was not retractable and produced considerable air resistance in flight.
(Click on image to enlarge)
Photo: Wikipedia Commons

The Avro 10 was not equipped with two way radios, which meant that once the flight had commenced, there was no way the aircraft could be contacted, or indeed, no way the aircraft could contact anyone on the ground. Whilst this situation seems incredible from today’s point of view, it was the accepted modus operandi in 1931. However, this shortcoming was to prove of critical importance in the flight of VH- UMF.

Because civil aviation was only in its infancy, meteorological services to the aviation industry were in the early stages of development, and the fast communications required to provide an efficient amendment and update service were yet to be developed. Meteorological observations were transmitted between the various weather offices by hand delivered telegram, and the synoptic charts (or “weather maps”) were only updated once per day using the observations taken at 9am.

When Southern Cloud departed Mascot, it was carrying forecast en route weather conditions prepared the previous day that were based on observations some 12 to 24 hours old. This forecast apparently indicated no extreme conditions, although a wind change, together with some shower and thunderstorm activity, was predicted.

However with the flight barely two hours old, the Assistant State Meteorologist in Sydney, Harold Camm, became concerned when a particularly strong cold front swept across Sydney.

The following cryptic extract from the official Sydney observations recorded in the Bureau of Meteorology’s journal notes the arrival of this front:

“March 21st 1931 – Light n’ly wind till 9am but strong, squally westerly change at 10am with driving rain….”

Camm anxiously awaited the arrival of the 9am weather observations from Victoria, and when they finally reached the Sydney Bureau of Meteorology’s office up on Observatory Hill by telegram delivery at about 1030 am, his worst fears were confirmed. A major cold front had indeed whipped across south- eastern Australia overnight and raging winds from the west and south - west were surging up into NSW from Victoria.

Cold fronts of this nature are more common in the winter months, but can occur at any time of the year, and are sometimes referred to as “cold outbreaks”. They are weather systems that drag cold polar air from the far southern ocean over south-eastern Australia and can produce highland snow, even during the summer months. For aviation, cold outbreaks can generate a whole raft of hazards, including very strong winds, severe turbulence, icing and reduced visibility in low cloud and rain.

In the modern era of lightning-fast communication, radar and satellite photography, it is inconceivable that a major front would ever be “missed”, but in 1931, such rapidly evolving weather events could easily slip through the network of slow reacting observation and communication systems.

Upon seeing the Victorian telegram, Camm immediately telephoned Australian National Airways management and spoke in person to Charles Ulm, who had gained previous fame as Kingsford Smith’s co-pilot during the late 1920’s.

Camm informed Ulm that the weather situation was far worse than originally forecast and that the Southern Cloud was probably encountering cyclonic weather with tremendous headwinds, severe turbulence, rain and even snow. However as the two men talked, they both knew that with the flight now over two hours old and with no way of contacting the aircraft, there was absolutely nothing they could do with this vital information.

At this time, far away to the south-west, across the wild peaks and ravines of the Great Dividing Range, the Southern Cloud would have been bucking into turbulent headwinds, rainsqualls and low cloud in a desperate battle for survival.

A grim wait began to see if the aircraft had landed anywhere, firstly at its scheduled refuelling point near Wangaratta, and then at any other airfield where they might have attempted to take shelter from the raging conditions. The nature of the front indicated extremely strong winds from the south-west were right across the flight path and the Southern Cloud would be struggling directly into these, slowing its ground speed dramatically. So at best, a late arrival was expected, but when the time of fuel exhaustion had well passed, it was realised that something terrible must have happened. A massive land and air search was launched and continued for several weeks afterwards, but no trace of the Southern Cloud was found.

A formal enquiry was convened soon after by the Air Accident Investigation Committee, and the final report contained a significant recommendation with regard to the Bureau of Meteorology. This concerned the necessity for more frequent updates of meteorological observations and synoptic weather charts, as well as the establishment of a forecast amendment service. Just as significantly, the report recommended that all passenger aircraft should be equipped with two-way radios. In addition, ground radio stations should be established to communicate with all passenger aircraft and to monitor progress towards their destinations.

The loss of the Southern Cloud was Australia’s first major civil aviation accident and had a devastating effect on aviation services in general. ANA went out of business later in 1931 and public confidence in air travel fell sharply. It only gradually recovered over a period of several years thereafter.

But remarkably, the story of the Southern Cloud was not over. Twenty seven years later, in 1958, a worker in the Snowy Mountains, Tom Sonter, stumbled across some strange, rusty metallic wreckage in a wild inaccessible part of the Kosciusko National Park. Closer examination revealed the presence of skeletal human remains.

The Southern Cloud had at last been found, and from its position, a more accurate reconstruction of the flight was attempted. An amazing picture emerged.

The aircraft had only managed to cover a distance of 353 km from Sydney, and if the flying time was calculated on a full tank of fuel, that represented an average speed of only 71 kph. As the cruising speed of the Avro was around 160 kph, this pointed to average headwinds of about 90 kph – a vindication of Harold Camm’s telephone warning to Ulm all those years before. In fact, because the early part of the flight had been conducted in far lighter conditions, the strength of the headwinds was probably much greater than this; it was even theorised that the Southern Cloud could have been blown backwards during the final minutes of flight.

A certain amount of speculation still surrounds the direct cause of the crash. Did the aircraft ice up, were they forced down by severe turbulence or did they attempt to descend below the cloud base in the belief that they were nearing Melbourne? This latter scenario is perhaps the most credible, as it is unlikely that Shortridge would have realised the extent of the headwinds opposing the aircraft. Perhaps it was some combination of all these, but the precise answer can never be known.

Today a memorial for the Southern Cloud stands near Cooma, NSW, containing pieces from the three radial engines. It is a reminder of the price that had to be paid in the quest for safety in aviation.

Reference: Australia's Natural Disasters, Richard Whitaker
New Holland Publishers, ISBN 1877069043

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