For many centuries Peruvian fishermen were aware of a warm ocean current that periodically appeared around Christmas time along the northwest coast of South America. It was dreaded by the locals because it decimated their main fish catch – the cold water anchovy.
They called this phenomenon El Niño – Spanish for “boy child” – and it was realised in more modern times that this was not just a local event but part of a broad warming of the equatorial Pacific Ocean waters that stretched thousands of kilometres westward from the South American coastline.
Further research into the phenomena showed that El Niño was part of an ocean temperature “see saw” that constantly rocks back and forth across the equatorial Pacific. Normally the sea surface temperatures across the western equatorial Pacific Ocean are much warmer than those in the east because of prevailing winds and ocean currents. However on occasion, this situation is reversed and the El Niño develops.
The El Niño pattern of sea surface temperatures. The thermocline referred to is the line that separates the mixed upper layers of the ocean from the calm, deep waters below. (Image from Wikipedia Commons)
And, as with most things in nature, there is an opposite phase, and this is when sea surface temperatures cool over the central and eastern equatorial Pacific Ocean, leaving the temperatures over the western Pacific far warmer. This configuration was given the name La Niña – Spanish for “girl child”.
Like the Peruvians with El Niño , the Fijians were aware of La Niña and they related it to the behaviour of the mango tree. They believed when the mango tree flowered early, a bad tropical cyclone season would follow. And there is science behind this observation as the tree will flower early when waters in the surrounding ocean are warmer than normal, and this in turn, promotes tropical cyclone development.
In modern terms we would say the same thing in a different way. That is, during times of La Niña, there is usually increased tropical cyclone frequency over the western Pacific Ocean – a neat convergence of ancient and modern science.
The La Nina pattern of Sea surface temperatures. (Image from Wikipedia Commons)
For much of the time sea surface temperatures across the equatorial Pacific are somewhere between an El Niño and a La Niña with cycles between the two occurring in an irregular fashion. When the temperature patterns are between the recognised El Niño and La Niña thresholds, the situation is said to be neutral.
El Niños tend to occur roughly every 3 to 8 years, and typically last for 12 to 18 months. La Niñas or neutral conditions predominate for the rest of the time.
Both these situations have a profound effect on Australian rainfall, including much of eastern Australia. The El Niño is normally associated with drier than average conditions for east and southern parts of the country, whilst La Niña conditions tend to promote above average rainfall over most parts of eastern Australia.
At present La Niña conditions predominate and we have seen a persistence of well above average rainfall over much of inland Australia during the last six months, with record totals falling over northern parts of South Australia, southwest Queensland, much of Victoria and southern parts of the Northern Territory.
At the moment we also have warmer than average sea surface temperatures to the northwest of Australia, and together with the prevailing La Nina conditions, this increases the possibility of above average rain over much of the continent during the remainder of spring.
Footnote 1: Whilst we have Spanish names for both the opposite phases - El Niño and La Niña – there is no such term for neutral conditions. I’ll bite the bullet and suggest “La Bamba”.
Footnote 2: Since this was originally posted in September 2010, much of eastern Australia has experienced its wettest ever spring and summer in what turned out to be one of the most powerful La Niñas in recent times.
"Aviation is not inherently dangerous, but to an even greater degree than the sea, it is terribly unforgiving of any carelessness, incapacity or neglect"...
- Unknown author
Flying conditions in Australia, when compared to many other parts of the world, are generally very favourable, with such phenomena as gales, blizzards and ice storms far less frequent than we see for example, in Canada, North America and Europe. Victoria is a good case in point, with meteorological conditions usually ideal for flying, and severe weather events relatively uncommon.
But severe weather is not the only way to produce hazardous flying conditions.
In light southerly winds, when the moisture content of the atmosphere is high,
low cloud – called stratus - often drifts in from the ocean across southern Victoria, and can cover extensive areas of the state, often as far north as the Great Dividing Range.
Around Melbourne, because of the comparatively flat terrain, it is usually safe to fly under this cloud, but over in the eastern areas, lie the Dandenong Ranges, and these are often covered in stratus during periods of moist southerly winds. As long as the pilot is accurately aware of the aircraft’s position, encountering cloud-covered terrain should never be an issue. But in the event of a navigational error it becomes a very different story.
Following the loss of the Southern Cloud in 1931, in which lack of communications played a crucial role, two-way radio was progressively installed in passenger carrying aircraft, and this quickly proved itself a real safety contribution.
However for the remainder of the 1930’s, passenger aircraft were still navigated by using manual techniques of estimating ground speed, noting reporting points and maintaining a navigation log, a process that became difficult at night or in thick cloud cover. Unlike the situation today, where pilots are aware of their height, location and speed to within an almost precise accuracy, the manual navigation process usually produced a certain amount of error, depending on the skill and experience of the Captain and First Officer.
But for Captain A. C. Webb and his crew, navigational issues were probably far from their minds as they climbed aboard their aircraft on Tuesday 25th October 1938, for a routine passenger flight Melbourne to Adelaide and return. They were flying the Kyeema, an Australian National Airways DC2, with the call-sign VH- UYC.
During the 1930’s, the DC2 was a thoroughly modern aircraft. Built by the Douglas Corporation and released in 1933, it was an instant hit with airline companies because of its superior performance and carrying capacity. Powered by two Wright Cyclone engines, each pumping out 875 horsepower, it could carry a crew of three along with fourteen passengers at 320 kph to a height of 6500 metres and over a range of 1600 km. This was a quantum leap forward from the old Stinsons and Avro 10’s of only a few years before.
A DC-2 in flight
(Image: Wikipedia Commons)
The DC2 was the first Douglas aircraft to be purchased by an overseas airline and in 1934 the Dutch company KLM entered one of its DC2’s in the London to Melbourne Air Race. In an astonishing performance, as it raced, it also completed its normal tasks of picking up mail and passengers and ended up flying more than 1600 km further than the race route. It finished second, behind a “one off” specially produced racing aeroplane, in what turned out to be a tremendous promotion for the Douglas Corporation.
The flight undertaken by Webb and his crew, from Melbourne to Adelaide and back, was only a short hop in comparison, and easily within the capabilities of the DC 2. The first leg began with an early morning take off from Melbourne, and proceeded routinely, with the aircraft landing about two and a half hours later at Adelaide.
Flying conditions were generally ideal, although a light southerly wind had produced extensive cloud-cover across the Melbourne basin, extending from the central business district across the eastern suburbs and over the Dandenong Ranges to the east. The base of this cloud – classical stratus formation - was around 450 metres but with lower patches around 250 metres – well above most elevations around Melbourne, but below extensive parts of the Dandenong Ranges which reach above 500 metres. These areas were in cloud for most of the day, under the influence of the cool southerly winds.
After taking aboard fourteen new passengers in Adelaide, the Kyeema turned around, took off on schedule and headed back towards Melbourne, in weather conditions that remained favourable for flying.
Amongst the newly arrived passengers were some notable citizens, including a Member of Parliament, Mr. Charles Hawker, MHR, the noted vigneron, Mr. Johann Gramp who was the managing director of Orlando Wines and the eminent barrister Mr. Leonard Abrahams KC. Also aboard were a honeymoon couple, Hans and Stella Gloe.
The Honourable Mr. Charles Hawker MHR (Image: Wikipedia Commons)
Soon after 1.30 pm Melbourne time, a transmission from Kyeema was received at Essendon Airport, confirming that the aircraft was passing over Daylesford, and about to enter cloud as it began its descent into Melbourne. The estimated time of arrival at Essendon was 1.45 pm. However, after another brief transmission from Kyeema, nothing further was heard, and when the aircraft had not arrived by 2 pm, the authorities became concerned.
In the meantime, near the top of cloud-covered Mount Dandenong, about 32 km to the east of Essendon Airport, two workers were clearing undergrowth from around a roadway. Macarthur Job, in his publication “Air Crash 1” recorded the events as they unfolded:
“In the eerie quietness of the fog enshrouded bush, both men gradually became aware of the distant whine of an aeroplane; the sound was coming from the west, roughly in the direction of Melbourne. And it seemed to be getting louder…. It was a big one all right and it was getting nearer and nearer all the time! The noise continued to grow in intensity; it wasn’t just a whine now. They could hear the powerful throb of the engines as well.
Suddenly, the noise of the engines and propellers was overlaid by a loud screeching; an instant later there was a sickening smashing of metal, then came a tremendous explosion which shook the ground beneath their feet…and a deathly silence”. The Kyeema had flown straight into Mount Corhanwarrabul, close to the main peak of Mount Dandenong.
The summit of Mount Corhanwarrabul. The Kyeema smashed into this peak about 50 metres from the top where the television mast now stands. (Image from Wikipedia Commons)
It was quickly established that all eighteen people aboard had been killed, and an official enquiry was convened at Melbourne’s Exhibition Buildings only three days after the disaster. This had been ordered by the Minister for Defence, Mr. Harold Thorby, as both civil and military aviation then operated under the auspices of the Defence Department.
After detailed deliberations, the inquiry found that the first cause of the disaster was inaccurate navigation. The investigators concluded that Captain Webb and his crew had failed to keep an accurate navigational log, which required them to monitor the speed of the aircraft and note when certain reporting points had been reached. As a result they had probably mistaken Sunbury for Daylesford (they looked similar from above) and were therefore about 32 km nearer Melbourne than they believed when commencing their descent into the deck of stratus.
As Kyeema descended in the overcast, Captain Webb believed he should emerge from the cloud base at around 1.45 pm near Essendon Airport.In fact he had actually flown well past Essendon, invisible below the cloud, and had descended straight into Mount Corhanwarrabul, about 32 km to the east.
The Kyeema overshot Essendon Airport and descended into Mount Corhanwarrabul
Although this represented a gross navigational error, it was also recognised that existing technology could have helped avoid this situation. Radio beacons were already available that provided pilots with a definite course along which to fly, and also enabled an accurate locational “fix” to be obtained.
The public were surprised to learn that a high frequency radio beacon had been installed at Essendon Airport some 18 months before the accident, but had never been made operational. Several experts afterwards claimed that this device, in fully functioning mode, would have prevented the accident.
As a result of the Kyeema disaster, a system of these beacons wasinstalled along the main inter capital city routes, providing pilots with instant and accurate navigational advice.
Another major change that followed was the appointment of so called “Flight Checking Officers” whose job it was to maintain a watch on the progress of flights on the main air routes. This “double check” was to guard against a pilot making a navigational error, as had happened with the Kyeema.
And, in another major change, the Australian aviation governing body, the Civil Aviation Board, part of the Department of Defence, was replaced with the Department of Civil Aviation or DCA.
The Kyeema disaster is now recognised as one of the watershed events of Australian aviation, generating a whole raft of changes that produced a major increase in safety to flying in Australia.
On October 25th 1978, the 40th anniversary of the disaster, a memorial plaque was placed on a cairn beside the roadway some 50 metres above the crash site.
The memorial cairn erected in 1978 close to the actual crash site. (Image from Wikipedia Commons)
Engraved on the plaque is the following text:
FIFTY METRES BELOW THIS POINT ON 25 OCT 1938 AUSTRALIAN NATIONAL AIRWAYS DC-2 ‘KYEEMA’ PLUNGED TO DESTRUCTION WHILE THE MOUNTAIN WAS ENVELOPED IN CLOUD. ALL 18 PERSONS ON BOARD PERISHED.
FROM THE RECOMMENDATIONS OF THE SUBSEQUENT ENQUIRY HAVE EVOLVED THE AIR TRAFFIC CONTROL SYSTEMS IN USE THROUGHOUT AUSTRALIA TODAY.
THIS PLAQUE, PLACED BY THE MOUNT DANDENONG HISTORICAL SOCIETY WITH ASSISTANCE FROM O. GRAMP & SONS, THOS. HARDY & SONS, S. SMITH & SON, AUSTRALIAN FEDERATION OF AIR PILOTS AND FORESTS COMMISSION OF VICTORIA WAS UNVEILED ON 25 OCT 1978 TO MARK THE 40th ANNIVERSARY OF THE DISASTER.
This memorial reminds us of the price we have had to pay for safe flying in Australia – as well as the ever-present need for accurate navigation in all airline operations.
Reference: "The Complete Book of Australian Weather", Richard Whitaker, Allen and Unwin, 2010
During the early months of 1944, the allied forces, under Supreme Commander General Dwight D. Eisenhower, had begun to get the upper hand in the battle with Nazi
Germany, and plans were put in progress to invade occupied Europe using a massive sea-borne army launched from England.
Above - The Supreme Commander of the Allies, 5-Star General Dwight D. Eisenhower. (Image - Wikipedia Commons - click to enlarge)
This assault force would have to cross the English Channel before landing at several beachheads along the French coast near Normandy. The entire military operation was given the code name “Overlord” and the first day of the invasion was to be called “D-Day”.
The timing of the operation was paramount – for military reasons it had to be a time of full moon and spring tide which immediately defined several windows of opportunity that could be accurately predicted from astronomical and tide tables.
However, the other variable, weather, was not so easily predicted. If rough conditions developed whilst the invading armada was at sea, an absolute disaster could have followed. In particular, the landing barges, crammed with troops, were vulnerable to capsize in even moderate seas, and soldiers in full combat gear and carrying weapons, would have little chance. Eisenhower was acutely aware that in such circumstances, his massive army of some 200,000 troops could be decimated before even reaching the battlefield.
Predicting the weather on possible invasion dates therefore became of paramount importance. The period 4, 5 and 6th June 1944 were periods of full moon and spring tides, and therefore became the focus for the weather forecasting team.
Predicting the weather in 1944 was much more difficult than today. There were no meteorological satellites, no computer simulations, and no organised network of automatic weather stations, as we see today. In addition, there was no international exchange of weather information because it was a time of warfare and weather conditions were classified as “secret”.
Meteorologists of the day relied mostly on “analogue” forecasting methodology. This consisted of
(a) Preparing today's weather map by delineating all the “highs”, “lows” and cold fronts.
(b) Manually searching the archives to find another similar map from the past.
(c) Looking at what weather followed in the historical example
(d) Assume the same would happen tomorrow.
The main problem with analogue forecasting was that it took little account of what was happening in the upper levels of the atmosphere. It was common to have two weather maps that were very similar but with different patterns in the upper winds, and this resulted in quite different weather to follow.
The forecasting team assembled comprised the top meteorologists from several countries. Group Captain James Martin Stagg, Superintendant of the Kew Observatory before the war was the head meteorologist, and he led the daily weather briefings that were held in the run-up to the invasion day.
The Allies Head of Meteorology, Group Captain James. M. Stagg
(Image from Wikipedia Commons - click to enlarge)
The American team included the well-known weathermen Benny Holzman and Irving Crick. The British had Charles Douglas, who was well known for his photographic memory of past weather events, and there was the brilliant Norwegian Sverre Pettersen, one of the foremost synoptic meteorologists of the day. In addition, experts from the Royal Navy were added to the team.
As the 4th June approached, Stagg advised Eisenhower that there was a strong low-pressure cell located over the North Sea and that gale force westerly winds were likely over the invasion area. Stagg considered that the 4th and 5th would be too rough to attempt a crossing. After considerable consultation between the senior military officers and the meteorological team it was decided not to launch on either day.
The weather map for 9am on June 6, 1944. The invasion area was under the influence of a weak ridge of high pressure, but with a deep low to the north.
The red arrows indicate the direction from which the wind was blowing. (Click to enlarge)
But Stagg and his weathermen then gradually reached agreement that the 6th may be suitable. The invasion area would lie between the strong “low” to the north and a weak high-pressure ridge that extended across Spain and southern France. The meteorological team considered that the influence of the high would be just strong enough to produce a temporary moderation in the weather. But it would be a close call – if the low moved even slightly southwards conditions across the channel could quickly collapse into gales and rough seas.
Eisenhower was faced with making one of the biggest decisions in history – stay or go in a marginal situation. His force was ready – a postponement would mean thousands of men would have to disembark, return to their land based units and wait for the next window of opportunity, increasing the chance of German readiness. To go would place his army at the mercy of a razor edge weather situation. He gave the order to go and 200,000 men went into action.
General Morgan, Eisenhower’s Chief of Staff, remarked to Stagg at the time
"Good luck Stagg: may all your depressions be nice little ones: but remember, we'll string you up from the nearest lamp post if you don't read the omens aright."
History reveals that the decision was the right one. The Germans had considered that the weather was too rough to attempt an invasion and were not on full alert and the allied forces were able to successfully cross the channel and establish beachheads. D Day was a resounding military victory and the Germans were put into a retreat that would ultimately lead to the collapse of the Third Reich in 1945.
American troops storm ashore from a landing craft, June 6th 1944
(Image - Wikipedia Commons - click to enlarge)
Interestingly the weather during the next window of opportunity, some two weeks later, was a disaster, with one of the worst summer storms in decades raging across the Channel. Eisenhower later confided to Stagg “I thank the Gods of War that we went when we did.”
General Dwight D. Eisenhower went on to become one of the most successful American Generals in history and ended the war a national hero. He became the 34th President of the United States and finally passed away, a revered figure, in 1969.
James Martin Stagg returned to civilian life after the war and became Director of the United Kingdom’s Meteorological Office. He was knighted in 1954 and as Sir J.M. Stagg was elected as President of the Royal Meteorological Society in 1959. He lived on until 1975 and goes down in history as one of the key meteorologists of the 20th century.
Reference: The Forecast for Overlord, J. M. Stagg, Ian Allen, 1971.
One of the oldest ways of forecasting the weather comes from the indigenous peoples around the world, including the Australian Aborigines. These techniques evolved over many thousands of years and involved observing linkages between the weather and the behaviour of various plant and animal species.
Initially dismissed by western science, it has only recently been realised that there is an underlying scientific basis underpinning much of the indigenous weather knowledge (IWK), and a renewed interest has resulted.
There are many examples of IWK, both from Australia and around the world, and only a few are given here – the first three from Australia and the other two from external sources.
(a) The gidgee tree: This is a type of acacia native to inland Australia, and the belief is that when you can smell the gidgee tree, rain is on the way. It turns out that when the air humidity rises, the tree exudes a pungent smelling sap. And rising humidity is often associated with the onset of rain. This knowledge comes to us through peoples from various inland areas of NSW and Queensland.
(b) Flying foxes: In the Northern Territory, these large fruit bats move from inland areas to the riverbanks when the dry season is imminent and back the other way when the wet season is about to start. This behaviour is used by the local people to predict the changes of season. A flying fox colony in northern Australia. (Image: Justin Welbergen, Wikipedia commons - click to enlarge)
(c) Brolga: The brolga is a large bird in the crane family. Its breeding is determined largely by rainfall and in the tropics takes place soon after the end of the wet season, from February to May. When breeding behaviour is observed early in the year it is taken as a sign that the dry season is imminent.
The mating behaviour of the brolga is used to forecast the onset of the dry season in tropical Australia. (Image: Wikipedia commons - click to enlarge)
(d) Mango tree: A belief common to several Pacific Island peoples concerns the flowering of the mango tree – if this happens earlier then normal it is said to imply an increased number of tropical cyclones in the upcoming season. The modern explanation is that the mango tree will flower early if temperatures are warmer than normal and this occurs across island areas when the surrounding sea surface temperatures are warmer than normal. And warmer ocean temperatures promote increased tropical cyclone formation.
These conditions are characterised by what we today call the "La Nina".
The mango tree in flower - the timing of the blossoms is related to the intensity of the upcoming tropical cyclone season. (Image: Wikipedia commons - click to enlarge)
(d) South American Sea Temperatures: For thousands of years, native Peruvian fisherman trolled for anchovies, a cold water fish that thrives off the coast of South America. However they observed that during some years warm water develops along the coastline, killing the anchovies by the hundreds of thousands. The local peoples monitored the ocean temperatures by immersion and “feel”, and when these warmer waters were detected, they planted increased crops of sweet potatoes in anticipation of reduced anchovy catches. Today we know this warm water development off the coast of South America as "El Nino".
Indigenous weather knowledge is a fascinating topic and because of its great antiquity forms a valuable goldmine of information that can be well integrated into today's scientific knowledge.
The Bureau of Meteorology web site contains some fascinating information on this subject at:
The El Niño pattern of sea surface temperatures. The thermocline referred to is the line that separates the mixed upper layers of the ocean from the calm, deep waters below.
