As a consequence of the accident in late August, I decided to include an explicit section on overhead hazards in my safety plan. As always, it is public and you can check it out here (the entry in the menu above will always refer to the most current version; this one is a permanent link to this particular revision).
I have received an incredible amount of very positive feedback about my recent essay, and it motivated me to address some of the questions that came up both in direct response to it and in other discussions.
This article is intended primarily for visitors who are concerned about various planned activities, and deals specifically with the situation in Iceland. A discussion detailed enough to satisfy glaciologists and outdoor professionals is clearly outside the scope of a simple blog post!
The answer, as one would expect, is complicated and depends on many factors. One could (and possibly should!) write an entire book on the subject, but we can certainly examine some general aspects. Here I will focus on the glacier itself, and particularly on the areas most commonly visited for tourism activities, which are snow free in the summer months (the ablation zone).
Let us begin by examining how a glacier evolves throughout the seasons. In summer, the glacier is exposed to near 24 hour daylight, warm temperatures and rainfall. This deteriorates the upper layers of the glacier in a way commonly called sunbaking – essentially each of the individual crystals melt along their boundaries until they entirely lose adhesion and become what is perhaps best described as a brittle set of loose puzzle pieces. Importantly, this does not only happen at the surface, but because the sunlight penetrates into the ice also progressively occurs into greater depths forming a layer that is called the weathering crust. This means that as this process continues throughout the summer, the glacier not only melts at the surface but also deteriorates internally, while at the same time loose fragments on the surface get entirely eroded away or dislodged by gravity, surface water, or other effects. Surface water also continually seeps into surface defects and can further affect the ice in ways not easily observed from the outside.
There are noteworthy exceptions, of course. For example, any glacier that is covered with substantial amounts of debris (such as volcanic ash in the case of Kötlujökull) may be protected from much of this effect and exhibit slower rates of change.
In winter, the glacier is either protected by snow cover (which entirely stops erosion) or is exposed to very little sunlight – this causes the weathering of the glacier in the winter months to primarily occur at the surface level, leading to the highly polished, smooth and glass hard winter ice.
With these basic processes in mind, we can now examine their consequences for various types of excursions on the glacier.
Consequently, if a glacier activity remains on the surface of the ice (such as a glacier hike), the loose and relatively soft summer ice is in many ways preferable. There is great traction with crampons, and the roughness of the sun baked crystals means that a person that fell down would just remain put in most normal terrain – although they may cut their hands on the sharp edges if not wearing gloves. Any degradation of the ice into greater depths is not a concern since we will generally walk on top of many meters of ice that is at no risk of collapse under our weight, and it is still very strong under the negligible compression of our body weight. Loose ice can be easily removed to access solid, blue ice underneath for building reliable climbing anchors.
In contrast, winter ice can be so hard that especially lightweight clients will have a difficult time finding good purchase with their crampons. The exposed ice is much harder, and even if the crampons have been sharpened to a sharp point do not penetrate very well. A stumble may quickly lead to a slide that is very difficult to recover from – so even otherwise very benign terrain may need to be protected.
A light snow cover greatly diminishes this risk once it has bound with the ice underneath. However, a more substantial layer of snow causes traveling over the glacier to become more hazardous, because windswept snow can easily obscure any dangerous spots in the surface. Larger moulins are likely to remain somewhat visible, but even a misstep into a smaller void underneath the snow could easily result in a sprained ankle, knee injury or other harm.
To protect from these fall hazards, good route choice and the use of fixed or temporary ropes are generally sufficient and easily managed.
Once we are exposed to any overhead hazards, the picture changes. In the summer, we routinely see smaller fragments coming loose under their own weight and harmlessly tumbling down surprisingly moderate slopes, and if the structure becomes steeper the chances of larger pieces breaking off increases dramatically. In particular, if a feature is free standing (such as an isolated wall) the sun baking may occur from multiple directions until there is no core with good integrity left.
We also need to keep in mind that while ice is very strong in compression, even in its compact form it is quite weak in tension, and any ice affected by sunbaking will exhibit dramatically lower tensile strength yet! We must therefore rely on any overhead features to be well supported on both sides, having a good, self supporting shape, and suitable thickness.
Whether we encounter those overhead hazards on a normal glacier hike (maybe walking a bit into an accessible crevasse, like routinely done on Falljökull, or into a moulin as it has been popular on Breiðamerkurjökull), because we are suspended from a rope and climbing up a vertical wall, or going into an ice cave does not necessarily change the character of the hazard.
What does change however is how long we are exposed to the risk, and if that particular location is an essential component of the tour program or can be easily avoided.
On a glacier hike the guide can always choose to not approach any vertical or overhanging terrain at all, or if it cannot be avoided mitigate the risk by limiting the duration of the exposure (very much in the same way one would pass through a potential rockfall area without stopping).
For ice climbing, we must indeed be in sufficiently steep terrain that allows the client to learn good ice climbing technique and gives a good experience – but since essentially all commercial ice climbing tours are top rope scenarios, loose material can be easily managed from above before the client proceeds to climb.
Therefore, for both glacier hikes and ice climbing, approaching and inspecting the overhead feature closely is generally possible without much additional effort, and allows for good and timely judgment of its condition.
With ice caves, the whole premise of the tour is to spend the majority of the duration exploring areas underneath the surface, and thus the overhead hazard is continually present or at least cannot be avoided when entering and leaving the area. Space is often limited and there is not enough room to avoid prolonged exposure overhead hazards. In a sufficiently large cave, the inner sections are often covered with sufficiently thick and homogenous ice that a collapse is unlikely – although there have been exceptions with pieces of the otherwise stable roof flaking off, icicles forming overhead, embedded rocks threatening to melt loose, etc. Furthermore, inspecting many of those overhead features in detail is generally more difficult, if at all possible, more time consuming, usually requires leaving the group temporarily unattended, and may therefore be limited to infrequent checks. Those may be sufficient in the winter months, when the rate of change is generally relatively slow, but becomes extremely problematic during the summer.
Of course, the integrity of the ice is not our only concern on glacier excursions. Common to all activities is that there is generally no easily accessible shelter from severe weather (except in larger ice caves, which can remain surprisingly comfortable even if there is a raging snow storm on the outside).
Also common to all glacier activities is that most clients are unfamiliar with the use of crampons, and the risk of self injury or stumbling certainly needs to be considered. Ice axes and ice climbing tools further increase this risk, especially when used or carried incorrectly.
Particular to ice climbing, protective eyewear is important to prevent injury from ice spray and clients with poor technique are at a considerable risk of hitting their knuckles when placing the ice tools. Bystanders, including the guide if belaying from below, are at risk of being hit by ice dislodged by the climber. And clearly the proper use of all safety equipment and good belaying technique are critical to ensure a potential fall of the client is caught safely. Warm temperatures and sunbaking require the rope anchors to be carefully planning and constructed, protected from unnecessary deterioration, and may need to be checked frequently. Ice screws have high thermal conductivity and may melt the ice surrounding them, becoming loose over a relatively short time if ambient temperatures are high. This is less of a concern in the winter months.
Ice caves are generally formed by subglacial water flows or geothermal activity. Those water flows generally subside in the winter when both meltwater and rain are diminished, but especially during warm spells and spring can increase dramatically. Water held back by the glacier in subglacial or marginal lakes may spontaneously drain as a jökulhlaup that could reach into ice caves or the proglacial area around the cave. A warm spell and rain falling onto snow cover can release substantial slush flows that might drain into exposed areas such as moulins. Geothermally formed ice caves, if poorly ventilated, can accumulate high levels of toxic gases, or reduce oxygen concentration with inert gases to dangerous levels.
Finally, sloppy or poorly maintained safety precautions can substantially increase risks. A rope, handrail or bridge will be trusted by customers to be reliable and trustworthy. On a warm, rainy day it may take only a few hours until an ice screw melts loose enough to be dislodged with minimal force, and while V threads generally last longer they too eventually melt out. In both cases whoever was pulling on the rope to keep their balance will have a very nasty surprise. Poorly tied knows may come undone with catastrophic results. Ropes left to freeze onto the ice may snap loose once a client pulls on it, throwing them off balance. In all of these cases, it might have been safer if there were no rope in place at all!
In summary, one could very generally say that –
While both glacier hikes and ice climbing occur in environments that are more easily managed, and there generally is a much larger range of options to choose from, ice caves are dramatically more limited in number and allow fewer alternatives for risk mitigation or avoidance.
There have certainly been years where exceptional conditions allowed ice caves to be visited earlier than normal, later into the spring, or perhaps even in mid summer, but we must be careful to ensure that such an exception does not continually become the new norm due to outside pressure or expectations.
Ultimately, glaciers are a rapidly changeable environment. Safety plans, regular site evaluations and standard practices are all valuable tools but cannot replace a well trained guide who is able to competently assess the situation in the moment, and also has the authority to make possibly drastic decisions about any tour. This requires training, experience, and a supportive work environment.
This unpredictability is why almost all guide companies will not generally offer ice cave tours outside of a time frame where experience over the past decades has shown that visiting them can be performed in a safe fashion, and even within the winter months sometimes must be canceled.
The tragic collapse of an ice cave left us mourning the loss of a life, a family torn apart and many lives irrevocably changed. I have just returned from two days on the site of the incident, and staring at the computer screen I keep asking myself the same question again and again: How on earth could this happen?
This post is my attempt at answering this question, because only if we fully understand what went wrong can we hope to prevent it from happening again in the future.
My knowledge of what exactly occurred and even which guides or companies are involved is incomplete, so we must satisfy ourselves with exploring all possible options, not all of which may actually apply – but we will see that there is somewhat of a golden thread through this discussion.
I am not even going to name the company involved, because this is a systemic problem that has pervaded the entire industry. The first symptoms have been showing up for years, and critical voices were constantly ignored. So while clearly one company took things too far, this does not absolve everybody else from also taking a very long, hard look at our own practices, and trying to see where we can do better.
First of all, it must be abundantly clear that the final decision on safety aspects of any tour must always be made by the guide who is on site. They are the last defense against any other safety measures that failed or were overlooked.
This requires training, experience, and the right mindset. A young and inexperienced guide, possibly with minimal training, is much less likely to have the confidence to “disappoint” their customer by turning away from something that maybe their gut instinct tells them is not looking quite right… but yesterday everything also went well so why should something happen today?
There is a very good reason why any formal guide training is usually in stages, where guides become increasingly independent – going from trainee (guiding under direct supervision by a more experienced guide), to apprentice (guiding under indirect supervision), and then finally to full guide (where they have accumulated enough experience to be able to make the correct decisions 99% of the time, and know how to safeguard against not catching the remaining 1% before it is too late).
The tour itself may be very low key – after all, most glacier experiences are at a level that is entirely suitable for first-time visitors – and not require any particular skills from the clients on a day-to-day basis. In many ways it is reminiscent of the job that flight attendants have – if all goes well it looks like they are just there to serve in-flight refreshments, but they are exceptionally well trained to deal with a variety of emergency scenarios that are incredibly unlikely.
All of this also requires the right company culture, where this process is encouraged and supported, and guides know their superiors will have their backs — even when they turn back and need to refund large sums of money to disappointed customers.
The company operating the tour, as a whole, is perhaps the central figure in this picture. They construct the tours, determine group size, locations, time constraints, and all other aspects of the operation.
Importantly, they determine which qualifications the guides have they will send out on each tour, under which constraints those guides operate, and most importantly also establish a certain company culture. In some instances there may be a construct of subcontractors, which is usually little more than false self-employment, and I think we can safely ignore this fact and just consider those as a single organization.
A guide that is sent out with minimal qualification and training, as pointed out above, will not have the necessary tools to make good and safe decisions, and will need to rely on instructions from their superiors – who may not be on site, and may be using outdated information. One of the critical aspects of late summer is how rapidly glaciers change, especially in August and September when they have been baked by sunlight and warm temperatures, and infrequent reviews are entirely inadequate. It would have been the company’s responsibility to ensure safety checks are performed sufficiently often, which in this time of the year may indeed be every single day.
Even with proper training, a company that encourages a “laissez-faire” approach to safety may weaken the guide’s perception of risk to the point that their own threshold for what is acceptable changes as well (“all the other guides still go, so it must be okay and my own perception must be off“).
One illustrating detail in this particular case is that it turns out we were looking for two additional casualties that did not actually exist – the total number of participants on the tour had been miscounted. In any mass casualty event, tracking and accounting for every single person involved is one of the most critical aspects. It is therefore quite surprising that in the moment when two persons were not accounted for, the numbers were not immediately verified. One would think that this would have been easy enough through the online booking systems even the smallest companies use nowadays, where people are “checked in” as they arrive, or at least tracking credit card receipts if there was a suspicion people had “walked in” without prior arrangements). Obviously each guide must have known how many passengers they had in their vehicles, or the clients themselves could have been interviewed to find out the seating arrangements and deduce any missing individuals, but humans are notoriously unreliable and possibly disoriented in the aftermath of such events.
In any case, the fact that the reported and actual numbers neither matched nor were corrected quickly does lead one to believe that the processes for tracking and accounting for customers on these tours were inadequate, or not followed, which may be symptomatic of a rather lax company culture in general (and thus possibly also towards safety).
Furthermore, a guide who is under tremendous pressure from their superiors may feel obligated to proceed with a tour against their better judgment, for fear of losing their job or prestige within the company. This problem is of course even more amplified if the guides are young and/or inexperienced, which makes it even more difficult to push back against one’s superiors and cancel the tour anyway.
Finally, we should not forget to consider why a guide company feels the need to compel their guides to run certain excursions. And in my opinion, online travel agencies / marketplaces play a substantial role here. They are often the customer facing entity, during the booking process, and for many clients indeed indistinguishable from the actual operators.
Almost all companies also operate their own direct booking websites, but it is safe to say that for most tour operators the vast majority of clients will come through the major OTAs (Arctic Adventures, Guide To Iceland, Tröll, Viator, etc.).
As such, the OTA can potentially create a tremendous amount of pressure, especially if they are effectively the sole source of customers for a given tour operator – and just like as a guide, saying no to one’s superiors is difficult for fear of being replaced by another, more willing guide, a tour operator that declines to offer a certain activity may end up being replaced by another supplier. This, coupled with the misguided assumption that if other tour operators are willing to arrange a certain activity, it must be possible to do it safely, spirals into a continued decline of boundaries and possibly safety standards.
It takes very strong leadership as a company to push back against this market pressure, but I would also fault the OTA for creating this demand in the first place. They, of course, may be willing to sell anything since for them any activity results in a neat commission and basically no operational risk, and if they can offer something that the other OTA’s don’t have (such as a summer ice cave tour), they will really want to have that cake. And therefore they will prod the tour operators towards extending their season further and further until it becomes year round.
At the same time, if the OTA would have done their due diligence and evaluated the possible risks involved with each of the activities they offer, they might have come to the conclusion that such a tour cannot be operated safely, and thus never include it in their program. As such, they too failed to defend and protect their customers against an activity that for many years was well known to be too dangerous to consider but crept into the common marketplace in very recent years.
And where does this leave the customer?
It would be easy to say that each customer is ultimately also responsible for their own safety, and if they would do their due diligence they should be aware of the risks involved and consciously accept them when booking.
That, in my opinion, is mostly incorrect. Of course we all are in the end responsible for our own wellbeing, but especially when it comes to guided tours we book those precisely because we are venturing into an unknown environment, and trust a trained professional to make it a safe and enjoyable experience.
Very few clients of glacier hikes or ice cave tours have the necessary knowledge, training or experience to accurately evaluate what constitutes a safe or unsafe environment, and even less so from a brief description on a website in a country that they may have never visited before (and thus also cannot really judge for example how the local climate factors in).
A certain amount of perceived risk, even if it does not relate to any objective danger, may even a welcome part of the experience of being on an adventure. But it is of course unacceptable to expose customers, oneself, or third parties to any objective dangers, perceived or unseen by customers.
The guide failed their customers because they did not perceive, address, or avoid a severe overhead hazard they were exposing their clients to during the tour.
The tour operator failed their customers because they were willing to arrange an activity that carries a very high risk in a highly volatile environment, without giving their guide the necessary tools, training, and support to mitigate the risks involved.
The online travel agency failed their customers because they were willing to sell those tours, marketing them as an entirely safe adventure.
But wait, there is more. The National Park, as the overseeing agency of all commercial operations within its territory, failed its visitors because they did not sufficiently monitor the commercial activities, perceive the increasing risks associated with those activities, or take suitable action.
Any one of those could have avoided the tragedy with suitable actions. None did. Out of complacency, financial motivation, external pressure, or ignorance.
How can we ensure this never happens again?
Some may point to quality management programs like VAKINN, but I very much doubt that is an actual solution. I have seen too many actions of guides from certified companies that are in clear violation of these standards. Paper, after all, is very patient.
Neither would a blanket ban on “summer ice cave tours” per se work. A sufficiently motivated company could easily just label them as glacier hikes of some sort where most of the time happens to be spent inside one of those structures. When ice climbing or visiting moulins, one could easily end up in a place that is quite similar in structure to the incident site but objectively safe and possibly the most memorable moment of the tour.
The only solution, in my opinion, is a thorough cultural shift that pervades all layers of the tourism industry.
We must put our customers’ safety at the front, throughout every decision we make. From OTAs ensuring customers come well informed about the right clothing and a good concept of what the tour might be like or how it might need to change, to tour operators and guides providing them with the right equipment and instructions. Guides having full authority over cancellations or changes as well as the training and experience they will need to make those decisions. Encouraging a company culture that prioritizes safety over all other aspects of the tour (including whether it takes place at all or not), having online travel agencies that decline to carry overly risky activities and explain to their potential customers why some tours may be seasonal, and having a National Park where the rangers have the training, authority, and legal framework to put a stop on commercial activities that are deemed unsafe. I could also envision an expert panel that reviews these activities, perhaps by anonymously booking them as seemingly regular guests.
Is all of this likely to happen? Probably not.
But one can dream, and one can set an example and hope others will follow.
Which is why write incident reports whenever I feel there is an important lesson to be learned. Why my safety plan is public, for everybody to read and hold me accountable for. Why I am organizing training days that are free of charge for other guides. And why in this text I am desperately grasping at ways to extract some sense of meaning from an event that should never have happened.
Because I want to live in a world where nature in all her beauty is enjoyable, exciting, an adventure — but first, and above all, safe.
It was time for my annual review of our safety plan — no major changes, but it is good to go through everything that we encountered over the past year and see if anything could be done to improve the situation.
Maybe the biggest change that has come from this was the observation that many clients could benefit from being able to rent boots – especially when ice climbing, where the rigidity of a full-blown mountaineering boot vs. softness of normal hiking footwear can make or break a great climbing experience. So I just ordered a number of B2-class boots (rigid soles, compatible with stiff, lever-lock crampons).
Otherwise, most changes were clarifications where I felt like certain sections were a bit unclear, or where experience showed that some additional steps were warranted. But overall, the safety plan has served us well over the past year.
As always our safety plan is of course public. You can find it here.
I’ve just uploaded a new revision of our safety plan…
The main updates in a nutshell:
A recent search & rescue mission brought up an interesting topic that I thought would be worth writing about in more detail. Part of the difficulty in this mission was to locate the party in distress due to the inaccuracy / miscommunication of their position, despite them carrying a GPS device which should provide a location accuracy of about 5-10 meters in average conditions – more than good enough to find anybody even in a fairly severe snow storm.
When communicating a position on the globe, there are a multitude of options that all have their advantages and drawbacks – but for the precision required for everyday use the simple specification of degrees latitude and longitude is entirely sufficient and the most common method. Latitude is a value between 0° and 90° north or south, and longitude is between 0° and 180° east or west, with 0° latitude being the equator and 0° longitude the prime meridian at Greenwich. South and west values are often specified as negative values, but not always.
While this has become the de facto standard for communicating global positions, there are different ways in which those angles can be specified. Similar to how hours can be split further up into minutes and seconds, latitude and longitude are commonly subdivided following the same rules (except that one minute is not 1/60 of an hour, but 1/60 of a degree). To further complicate matters, there are actually three common methods: decimal degrees (often abbreviated DD), degrees / decimal minutes (DDM), or degrees / minutes / seconds (DMS). So while the degrees value is always the same, the fractional part of a degree is either written as a decimal value (“Decimal Degrees”: 17.48°) or in 1/60ths (17°28.8'), and since the minutes value is also often fractional the same applies – we can either just write it out as a decimal too (as we did before) or do the same conversion again to arrive at seconds (17°28'48").
Here are three scales showing the same values in each of these systems:
Generally speaking, they are often written down as dd.ddddd° , dd°mm.mmm', or dd°mm'ss.s" respectively (with d, m, and s representing digits of the degree, minute, or second values, and the °, ‘ and ” symbols to differentiate them). This gives approximately the same precision in each of the representations and is accurate to about three meters, similar to the actual positional accuracy achievable with consumer grade GPS devices. It is also common to omit the least significant digit if less precisison is required / available (for example, dd°mm'ss" or dd°mm.mm').
Most notably these representations all have the exact same number of digits and are potentially close enough in value that it may not be immediately obvious which representation was chosen. Therefore when communicating coordinates it is extremely important to be clear about which of these systems are being used, to ensure that the receiving party interprets them correctly.
In Iceland, it is standard practice to use DDM (degrees and decimal minutes) to specify coordinates, both within the search & rescue and other emergency response teams and the Icelandic Coast Guard. If the coordinates are given up in a different system by third parties, they are generally converted to DDM before being communicated to the responding SAR teams.
With a refresher of those fundamentals out of the way, we are now ready to look at the situation on Grímsfjall in detail.
The notification we received was, roughly translated:
(more or less direct translation of the alert message I received on my phone)
Priority 2-Injured person - 64°24,400' N 17°15,150 W, near hut/shelter - [...] - mountain rescue, injured ski mountaineer 1km east of the Grímsvatn hut. [...]
If we place the specified location on a map, it all checks out:
The location is indeed about 1km more or less straight east from the hut that ski mountaineers often visit during their traverse, it is roughly on the route that people take off the mountain (though a bit too far north, there is a large moulin further east that needs to be avoided by diverting south – but still plausible). So no reason to doubt any of the information.
Except when our snowmobile team arrived, there was nobody to be found at the specified location. We know GPS positions are not always exact, and visibility was severely limited to the point that the group could easily in fact be nearby this location but simply invisible, so they were carefully extending their search radius as far as it was feasible without too much risk – but to no avail.
It became increasingly clear that something must be off, and eventually the mistake discovered: the position had in fact been given in DMS, and was thus 64°24'40" N 17°15'15" W (and not 64°24,400' N 17°15,150 W). But somewhere between their communication and the information the search & rescue teams had received, it had been written as DDM. We do not know if it was a language problem or other miscommunication between the caller and the emergency hotline, or a mistake that was made upon entering the call into the system and notifying SAR.
Here is where the DMS position places us:
Now, in many ways this location makes more sense – on the initial location it is somewhat difficult to imagine how a person may sustain severe injuries while a 200m fall would definitely produce those, but in others it doesn’t: it is to the northeast of the hut (not east, as communicated), and the near vertical slopes / cornices to the north of the mountain are nowhere near the regular routes up / down the mountain.
But for the ongoing rescue, the new location also produced some other issues. The concentric circular elevation lines in the map already hint at the instability of the glacier in the area, which is sitting on top of a rather active volcano and made the approach and rescue a much more difficult and potentially hazardous operation than initially anticipated. From the original position, it would have been quite easy for the snowmobile teams to transport the party back into the shelter of the mountain hut and then await evacuation in a closed vehicle, but the new position required careful planning and even more careful progress using snowmobiles, heavily modified superjeeps, and a snow cat. A rope team scouted the very last stretch on foot before allowing vehicles to drive into the potentially unstable terrain.
Ultimately the rescue was a complete success, and in retrospect not too much time was lost overall due to the miscommunication – the slow moving but very gentle snow cat that was used to transport the injured person was still on its way and could not have reached the incident location much sooner anyway (we also decided not to move her before everything was in place, so that she could be transported from the relative shelter of the group’s tent to the snow cat in one go). An earlier assessment of the injured person and the other members of her group would have been desirable but fortunately in this case it did not change the overall outcome.
However, it remains a good opportunity to look at what went wrong in more detail, and how a similar situation can be avoided or identified more quickly in the future.
Of course, some of the possible mixups of latitude/longitude figures could be easily identified. If the digits would result in, say, the minutes or seconds value to be 60 or more, that would be easy to catch as invalid (since the degrees or seconds values should never be more than 59,9999…). And some resultant locations are very obviously so far away from the true position that they are easy to exclude (if somebody is in trouble on a mountain, they clearly aren’t going to be in the middle of the ocean). It is the near misses that are dangerous.
Let’s take the example of above and see what the options are for each of the “wrong” combinations and how far off they would be. For simplicity we will just look at the latitude in the table below:
| Actual Coordinates (position converted between DMS/DDM/DD) | 64°24.67' | 64°24'40" | 64,4111° |
| .. misread as Degrees / Decimal Minutes | ( correct ) | 64°24,40' | 64°41,11' |
| … misread as Degrees / Minutes / Seconds | 64°24'67"(implausible) | ( correct ) | 64°41'11" |
| … misread as Decimal Degrees | 64,2467° | 64,2440° | ( correct ) |
So in addition to the actual correct position, there are six possible misreadings, depending on which combination of coordinate systems were used vs. expected.
It may be worth pointing out that while that 64°24'67" value is technically incorrect, it is equivalent to 64°25'07" (just like 90 minutes and 1 hour 30 minutes mean the same thing), and many mapping tools will interpret it as such. I used the PROJ tools of the OSGeo project to make these calculations, but for example Garmin’s BaseCamp also happily accepts the “wrong” value. So while it is an indication to the watchful eye that something may be amiss, we can’t necessarily rely on the tools to tell us so, as they will not reject it as a malformed value.
We can then calculate how far off they are (now using both latitude and longitude, of course):
| Degrees / Decimal Minutes | Degrees / Minutes / Seconds | Decimal Degrees | |
| .. misread as Degrees / Decimal Minutes | ( correct ) | 500m | 31.6 km |
| … misread as Degrees / Minutes / Seconds | 830m | ( correct ) | 33.6 km |
| … misread as Decimal Degrees | 18.9 km | 18.7 km | ( correct ) |
You can clearly see how the two closer misreadings (bold above) are actually still rather plausible given a brief description of the approximate location, whereas the other four, more distant points would most likely be immediately ruled out.
More generally speaking, we can also make an estimate of the possible range of those misreadings. A latitude of 64°00'00" is exactly equal to 64°00.00' or 64.0000°, so there is no difference there at all. But what is the largest possible deviation? If we consider, for example, 63°59'59", then misreading this as 63.5959° is about 0.4° off – a 45km difference! Similarly, 63°59'59" and 63°59.59' are about 0.4′ apart, which is still about 730 meters. Differences in longitude vary with latitude and are less (at 64° latitude, about 20km and 320 meters respectively). If we allow malformed readings, the possible error increases even further to 74km and 1230m (for 64.9999°, 64°99.99', and 64°99'99").
Fortunately, by looking at the above table it is easy to see that no matter how the point was specified, one in three choices will necessarily give the right answer. So we only really need to consider three possible locations and can be assured that the correct value will be one of them.
I have made an interactive tool that allows you to do just that – enter coordinates either as an “anonymous” stream of digits or in any of the three standards (DMS, DDM, or DD), and it shows where all these possible points end up on the map. It also automatically converts each of these interpretations to the respective other coordinate systems, which may be useful. You can find it at https://tools.stepman.is/gps.
So, what does all of this mean for us?
Clearly one should always use the tools and methods one is most familiar with – this will keep you from making mistakes in particularly stressful situations and an emergency is not the right time and place to start changing the settings on your GPS to what you believe the other side wants to hear. No matter which system you end up using for your location, always explicitly specify it to the receiving party, and ensure they read it back to you correctly. And always add additional information that specifies the landscape around you.
“Our location is in Degrees and Decimal Minutes: North Six Four Degrees Two Four Point Six Six Seven Minutes, West One Seven Degrees One Five Point Two Five Minutes. We are at the bottom of a very steep slope at an altitude of about 1450m. The terrain seems to become much flatter to the north of us.”
For serious endeavours, PLBs or satellite messenger devices like Spot or InReach add the additional safety of automatically transmitting your precise location to the rescue center with any emergency transmission, so there is no need to worry about coordinate systems at all. However, any additional information you can pass on (such as “we are at the very bottom of the steep slope to our south, and the terrain appears to be much flatter to our north“) is still very valuable for planning and executing your rescue, so please do communicate these observations if you can.
Stay safe!
In mid June of this year I was called for a rescue operation on the highest mountain of Iceland, Hvannadalshnúkur. This operation was widely reported and I had also written a short post about it earlier.
I had planned to delay publishing my own incident report until after the guides involved had published theirs, but have now come to the conclusion that it is not forthcoming. If their account of the events does become available in the future, I will edit this post to include a link to that as well.
You can download my own incident report here.
Names and other personally identifiable information have been redacted from this version.
On my day tour on 2019-12-28 I came to the assistance at an accident on the glacier. You can download my incident report here.
Names and other personally identifiable information have been redacted from this version.