Weather and Situation Awareness in Aviation

– By Hyun Su Seong –

Introduction

Pilots in general or commercial aviation rely on accurate weather forecasts to avoid dangerous cell activities during instrument meteorological conditions. Pilots use several weather products to make decisions for their pre-flight activities and in-flight. There are two types of weather products: Alphanumeric (METAR, TAF, SIGMET, PIREP, AIRMET) and Graphical (Upper-Air Analysis, Surface Analysis etc). The former is a text and does not contain images, whereas the latter is a graphical visualization of where convective weather occurs in a specified region. Below is an example of METAR.

METAR CYXU 141600Z 34009KT 270V360 15SM SCT026 20/13 A2985 RMK CU3 SLP109 DENSI ALT 1900FT=

The translation is as follows: London International Airport / June 14th, 1600 UTC / Wind 340 True at 9 knots with variation 270 to 360 degrees / Visibility 15 statute miles / Scattered clouds (3 – 4 oktas) at 2600ft / Temperature 20°C and dew point 13°C / Altimeter 29.85 inches of mercury/ Remarks: the lowest reported cloud is Cumulus with 3 oktas / Mean sea level pressure 1010.9 hPa / Density altitude 1900ft.

Outside the aviation community, METAR may look like a mix of incoherent words and numbers. I have always wondered how pilots focus on flying an aircraft while monitoring and decoding such a complicated text. I found out that this is largely because pilots have good situation awareness.

Weather and Situational Awareness

Pilots and ground controllers are used to seeing much more complicated forecasts than above. With experience, they have gotten used to decoding and understanding alphanumeric forecasts without the need to frequently revisit aeronautical information manuals. Experience allows the development of heuristics (or mental shortcuts) and therefore helps in processing only the necessary information faster. There is a possibility that introducing a new system to replace alphanumeric products might cause confusion for some pilots because there would be a steep learning curve in adapting to new design specifications. This can be illustrated with a simple example of computer coding. Suppose there is a programming module a programmer wants to import into his code. He was familiar with the module and had prior experience in using it. Unfortunately, his codes fail to execute several times because the program could not locate certain functions from the module. He visits the module’s documentation and finds that much of the old functions now have been deprecated (it means they are replaced by newer codes in codebase). This means that he must rewrite the code in a different way to successfully load the desired function. It will take time for the programmer to navigate and learn how to write a code using that module again. Thus, just because a new system (or product) is introduced does not mean that one can easily adapt to it. It takes time to replace previous knowledge.

In the case of aviation weather, a new system may result in either a pilot struggling to interpret weather or become complacent (that is, they trust the new system so much that they eventually lose the ability to decode alphanumeric forecasts). The problem with complacency is that when the new system fails, a pilot flying (PF) is forced to go back to traditional alphanumeric products which he or she may have forgotten how to understand. Whatever the case, it is not ideal in an occupation where multiple decisions in the span of few minutes must be made to protect the lives of passengers. This is the reason why a new system or product must be rigorously scrutinized and tested before it is introduced to the market. If it is introduced without a careful examination, a user will not be able to maintain situation awareness. This will negatively affect user’s performance.

In human factors engineering, situation awareness (SA) is defined as “the perception of the 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” (Endsley, 1995). The definition contains the three levels of SA: Perception, Comprehension, and Projection (Endsley, 1995). SA is not an action (Wickens, 2008). Rather, SA is a constant evaluation and conjoining of elements found in the current environment to make sense of the surrounding situation. Here is a simple example in the context of aviation meteorology. Suppose there is downpour and strong gust while a PF is preparing for landing and he or she recognizes turbulent weather during the descent (level 1). The PF would naturally look for recently issued SIGMET or METAR to understand the current weather at the destination airport (level 2). Finally, the PF sees the need for incorporating SIGMET information into the calculation of landing distance to avoid runway excursion or overrun (level 3). After this, the PF will execute an action (calculation of landing distance).

There are some interesting human factors studies that have practical implications for weather and SA. For quantifying SA, I refer interested readers to the research by Lim and Johnson (2012) which looked at the effect of different types of cockpit weather displays on pilot performance under two weather scenarios: convective and turbulence potential. This research may help readers understand why a certain weather display is still effective for SA than other types of displays. For the effect of pilots’ licenses and rating on their weather analysis skills, I refer readers to Blickensderfer et al. (2017) and DeFilippis et al. (2018). Both articles also provide useful insights on how to effectively train pilots for weather. Lastly, an article by King et al. (2018) shows why new products may cause more confusion and why many pilots struggle with weather analysis.

Implications

So, what implications do weather and SA have for a human factors engineer? If the engineer wants to improve ab initio pilots’ understanding of weather, he or she needs to choose which type of product to develop. When this is done, the engineer must consider the needs of pilots who are not well-versed in aviation meteorology. An exchange of their opinions via interview will help the engineer in brainstorming design specifications for a new product. Here, I should clarify that a ‘product’ could be a mobile app, computer software, website, or educational material. Next, the engineer – in cooperation with a subject matter expert (SME) such as a meteorologist – should clarify the purpose of the product development and establish a shared mental model to achieve a common goal.

The engineer should test the prototype by inviting participants to try it out. For instance, the engineer must confirm that the mobile app – in the opinion of the pilots – is a user-friendly product that does not interfere with their decision-making ability and ultimately SA. If it was found that the app takes too much time to toggle back and forth between interfaces or is cluttered with information, the engineer may need to fix and incorporate the new feedback from potential users. Again, the process of creating a new product is difficult and time-consuming. However, a well-designed product can have an everlasting impact on the performance of users. In this case, it would be maintaining good situation awareness by being well-versed in meteorological concepts.

Hyun Su Seong is a PhD candidate in systems design engineering at the University of Waterloo. His specialization is human factors and ergonomics. His research area is competency-based education with a specific focus on avialinguistics and miscommunication in pilot-ATC communication. He holds bachelor’s in commercial aviation management and master’s in geography. His master’s research area was aviation meteorology with a specific focus on tropical cyclones and their economic impacts on airports.