On the night of 14–15 April 1912 in the North Atlantic, the passenger liner Titanic collided with an iceberg and sank. There were investigations into the iceberg and the fatal damage the collision caused to the supposedly unsinkable ship. The most important sources about the iceberg are reports from surviving crew and passengers of Titanic. Photographs were taken of icebergs near the spot where Titanics lifeboats were found, and it is purportedly visible in one of these photos.

The iceberg was often seen metaphorically as a counterpart to the luxurious ship, standing for the cold and silent force of nature that cost the lives of over 1,500 people. It was also seen in various political and religious contexts, and has appeared in poetry as well as in pop culture.

Origin and fate

It can only be speculated where and when the Titanic iceberg calved from its glacier. Olson, Doescher, and Sinnott suspect the origin of the fatal iceberg in the Jakobshavn Glacier near Disko Bay on Greenland's west coast. It may have formed in 1910 or 1911 and could have drifted north with the West Greenland Current into Baffin Bay, from where it would have drifted south again thanks to the Labrador Current. An iceberg can, for example, be washed up on the coast or run aground. There it melts, or it comes free again and continues its journey south.

The authors also address the question of whether a certain constellation of the Sun, Earth, and Moon may have had an influence. On 4 January 1912, there was a spring tide at the same time that the Moon was closer to the Earth than usual. This could have influenced the calving of icebergs. Although an iceberg so calved would hardly have reached the site of Titanic disaster in April of the same year, the spring tide may have played a role in refloating a stranded iceberg.

Bigg and Wilton doubt that the solar arrangement of the Moon, Earth, and Sun in question was significant. A few days around 4 January would not have had much influence on calving; in winter, moreover, many fjords were blocked by sea ice. There was also increased iceberg formation in other years. When it comes to calving, they tend to think of factors like the water surface temperature of the Labrador Sea.Grant R. Bigg, David J. Wilton: Iceberg risk in the Titanic year of 1912: was it exceptional? In: Weather – April 2014, Vol. 69, No. 4, pp. 100–104, see p. 103.

For their part, Bigg and Wilton have tried to show a possible path of the fatal iceberg with the help of computer simulations. To do this, they assumed that icebergs at that time originated mainly in the south or southwest of Greenland, whereas today they originate more from the northwest of the island. In 1912, more icebergs were sighted than on average in the 20th century, but it was not an extreme iceberg year.

The warm and wet year 1908 created the conditions for a huge iceberg to travel in the early autumn of 1911 near southwest Greenland. This would have traveled west towards Canada and been transported south by the Labrador Current – along the Canadian coast and the island of Newfoundland, the so-called Iceberg Alley. Because of the systematic observations of icebergs at the time (even before the Ice Patrol was established), it is even very likely, according to Bigg and Wilton, that the later fatal iceberg was sighted in the process.

From 10 to 15 April, there was a high-pressure area over most of the North Atlantic. It remained there for the first three days of Titanic's voyage, ensuring calm seas and clear skies. On 13 April, a depression over Greenland with cold polar air and winds from the northwest drove icebergs south into the shipping lanes. Because of the calm sea, the icebergs hardly created any breakwaters, making them difficult to see at night.Megan E. Linkin: Icebergs Ahead!: How Weather Doomed The Titanic. In: Weatherwise, volume 60, no. 5, pp. 20–25, see p. 24/25. DOI:10.3200/WEWI.60.5.20-25

On its way into the Atlantic and also after the collision, the iceberg melted because of the water temperature. An iceberg exists for about two to three years, often in a state of vertical rotation as underwater melting changes the center of gravity of the top-heavy mass. Accordingly, if the fatal iceberg calved in 1910 or 1911, it may not have disappeared until the end of 1912 or even during 1913. However, considering that the iceberg may have been three years old at the time of the collision, it probably existed for only a week or two after the April 1912 accident, because it may soon have reached the warmer waters of the Gulf Stream.

Ice warnings

Captain Edward Smith and his officers knew before they left Southampton that the drift ice field was larger in extent and more southernly than in previous years. Additionally, Titanic wireless operators received seven messages from other ships warning of drifting ice.

The first warning came on 12 April from , a French liner, at 17:46. The message reported two separate ice fields and two icebergs as well as dense fog and "derelicts." Captain Smith acknowledged the receipt of this message. It was the only ice warning the ship received prior to 14 April.

On 14 April, an ice report came at 09:12 from the reporting "bergs, growlers, and field ice". Captain Smith acknowledged receipt of the message. At 10:28, the Caronia also forwarded an ice report from the which stated that "much ice" was reported to them. Smith also acknowledged this message.

At 13:54, relayed a report from the Greek ship Athenia that she had been "passing icebergs and large quantities of field ice". Smith also acknowledged this report. He showed it to White Star Line chairman J. Bruce Ismay, aboard Titanic for her maiden voyage, who later showed it to a few passengers before returning it to Smith after the Captain asked for it back a few hours later.Frances Wilson: How to Survive the Titanic, or the Sinking of J. Bruce Ismay. Harper Perennial, New York 2012, chapter 7.

It remains uncertain whether other officers saw the marconigram. Ismay was the director of the White Star Line, which owned Titanic. The incident with the Baltic marconigram fueled rumors that Ismay had exerted undue influence on the captain to keep Titanic from slowing down despite ice warnings. Thus, in the enquiries after the disaster, people wondered why Captain Smith showed Ismay the marconigram in the first place.Frances Wilson: How to Survive the Titanic, or the Sinking of J. Bruce Ismay. Harper Perennial, New York 2012, Kap. 7.

At 13:49, the German ship , which was a short distance to the south, reported she had "passed two large icebergs" and asked the Titanic to forward the message to the Hydrographic Office in Washington, D.C.. There is no evidence as to whether or not this message reached Captain Smith or to the bridge but it was acknowledged by the wireless operator aboard Titanic and forwarded to Washington via Cape Race wireless station, Newfoundland at 21:32.

At 19:37, the reported "three large bergs" to the SS Antillian, a message which was intercepted by junior wireless operator Harold Bride who took it to the bridge and later acknowledged its receipt to the Californian. At 21:52, the steamship reported: "Saw much heavy pack ice and great number large icebergs. Also field ice." It is unclear whether or not this message left the Titanics radio room as Jack Phillips, the radio operator on watch at the time, did not survive. He acknowledged the message, as per Mesabas wireless officer Stanley Adams, but the surviving officers could not recall seeing it later.

A final message was received around 22:07 from operator Cyril Evans of Californian, who signalled, "Say, old man, we are stopped and surrounded by ice." Phillips signalled back to Evans to stop transmitting, as the ship's stronger signal was interfering with the fainter one from Cape Race. He was preoccupied with transmitting messages for passengers via the relay station at Cape Race; as the radio set had broken down the day before, there was a backlog of messages that Phillips was trying to clear and the informal-sounding message by Evans was not sent with an official mark of "MSG" and also lacked coordinates.

Messages received by bridge By 1912, the wireless machine aboard ships was still a relatively new feature. Several ships carried one wireless operator, with Titanic being one of the few exceptions. It was seen more of a service to passengers rather than a necessary tool for navigation. Hence, there was no system for collecting and evaluating ice warnings, particularly for cases such as the Amerika warning which was received by the ship as a private message. The wireless operators, Phillips and Bride, were employees of the Marconi Marine Company and likely followed their general orders with regards to ice reports.Walter Lord: The Night Lives On: The Untold Stories and Secrets Behind the Sinking of the "Unsinkable" Ship Titanic. Morrow, 1986, Kap. 6.

Additionally, ships treated hazard warnings as advisories rather than calls to action. It was widely believed that ice posed little risk; close calls were not uncommon, and even head-on collisions had not been disastrous. One example had occurred on Titanics sailing day: on 10 April 1912, the French liner struck an icefield not far from where Titanic would a few days later, but managed to steam under her own power to New York.

It is unclear whether or not all the messages reached the bridge, as Phillips, Captain Smith, and three officers died in the sinking. In particular, the Mesaba and Amerika messages were not recalled by either Bride or any surviving officers. However, it is known that majority of the ice warnings received by the operators had been communicated to Captain Smith, as he acknowledged them in return. He was aware that there was ice in the area and, according to Second Officer Charles Lightoller, discussed this with him in length. Additionally, both lookouts were told to keep an eye out for "small ice and growlers" by Lightoller on the night of disaster and he passed this information onto First Officer William Murdoch who took over the watch at 10:00 PM.

Iceberg visibility

On the night of the disaster, Captain Smith assumed that an iceberg would be discovered in time so that it could still be avoided. The decisive factor for him was that the night in question was clear and cloudless. It was generally believed at the time that on clear, albeit dark, nights one could see an iceberg within one to three nautical miles. According to surviving Second Officer Charles Lightoller, he and Smith believed an iceberg was visible at three to four nautical miles. Smith had said that at the slightest sign of haze, the ship should proceed very slowly. The lookouts were instructed to pay particular attention to ice.Halpern 2016, p. 84/85, 88.

In 1925, Fred Zeusler of the United States Coast Guard was in charge of the International Ice Patrol. According to his research, a medium-sized iceberg could be seen a nautical mile away on a moonless, dark but clear night. On the night of Titanic disaster in 1912, Halpern says, the sea was calm and smooth. Therefore, an iceberg could not be seen from the break of the waves. The only light that could have come from an iceberg would have been reflected starlight. Visibility would have been even worse in the low-hanging haze purported to be extant on the night of the ship's sinking, but survivors' testimonies contradict each other as to whether there was any; other ships reported no haze whatsoever. Possible explanations could be that the witnesses understood different things by 'haze', or that instead of haze, the ice field was actually seen, towards which Titanic was heading and because of which the Californian had already stopped.Halpern 2016, p. 85.

Sighting and collision