Is the Sterile Cockpit Rule on Airplanes the Inspiration for Hospital “No-Interruption Zones”?

Written for the PhD course What we think about when we think about concepts and based on the concept implosion-method from Dumit (2014).

The No-Interruption Zone (NIZ), sometimes known as an interruption-free, distraction-free, or disturbance-free zone, is a recent phenomenon that has come to quickly permeate much of healthcare since the turn of the century. Several early NIZ studies experiment with the idea of a no-interruption space in medicine rooms that they argue is modelled after the aviation industries Sterile Cockpit Rule (Anthony, Wiencek, Bauer, Daly, & Anthony, 2010; Hohenhaus & Powell, 2008). The sterile cockpit is a rule widely adopted aviation regulations stating that no flight crewmember may engage in any extraneous activity during a critical phase of flight which could distract from the safe operation of the aircraft, see the image above.

However, the Sterile Cockpit Rule is a different practice than the NIZ on most accounts. Comparatively, the NIZ is not limited in time, but a permanent and spatially defined limit in and around medication preparation spaces in hospitals. The NIZ is described unanimously in the clinical science as a “zone” or “space” rather than a “rule”, again highlighting the spatial dimension of the NIZ rather than a contextual or timely nature of the Sterile Cockpit Rule. Furthermore, Sterile Cockpit practices does not include the common use of signs or posters, while the NIZ is usually marked in some way, sometimes by red tape on the floor or doors, or by signs and stickers on the doors to medicine rooms, see the image below. Sometimes, interventions extend out from the medicine room to include vests or lighting lanyards around the neck of nurses administering medicine to patients.

Examples of No-Interruption Zones (NIZ) from Raban, Lehnbom, and Westbrook (2013)

The origin story becomes even more confusing when you realize that aviation’s use of “sterility” is a term borrowed from healthcare. Aviation safety specialists will often cite healthcare logic as a justification and inspiration for the rule, e.g.: “No person about to undergo major surgery would think too kindly of the surgical team who failed to sterilize themselves and their operating instruments before the operation. After a series of air carrier accidents and serious incidents, the traveling public feels the same way about their crew members. Keep the sterile cockpit ‘clean’” (Sumwalt, 1993). So, although the Sterile Cockpit Rule provides a persuasive origin story for the NIZ in hospitals, it seems more like a story of mutual influence between the industries of healthcare and aviation. And not only that: use of visual signage, red color, etc. points to completely other causes as well. In this analysis, I trace these complex beginnings of NIZ practice in healthcare, to comprise a more comprehensive picture of how the practice works and why it has come to completely dominate medicine rooms in hospitals.

Political Space: Zoning and Nudging

An aspect of the NIZ that the Sterile Cockpit Rule “origin story” does not explain is the usage of posters and signs in doorways and stickers on the hospital floor. Especially red is used as a signal color. Where does these elements stem from is the question? Studies show that red color does imply danger to a western audience (David Leonard, 1999) perhaps as a result of societal enculturation (Pravossoudovitch, Cury, Young, & Elliot, 2014), but other studies show that visibility of danger signs are actually due to visual context, rather than color alone (Gershon, Ben-Asher, & Shinar, 2012). While signs with messages have been in use since antiquity, the pictorial warning sign/hazard sign that we also see used in NIZ practice became only widespread with the appearance of motorcars. Signage was required to regulate the complex movement of fast-moving vehicles. According to Wikipedia, 1909 was the year that nine European countries first agreed to use four universal pictorial symbols indicating bump, curve, intersection, and railroad crossing. The speed and complexity of the motorcar system required a regulation system, and the pictorial sign has since followed the car as its use spread around the world like its ecosystem.

During the early 20th century, the scientific and industrial revolution had gained enough traction to impact society in fundamental ways. Technological inventions such as the automobile and the influx of people to cities made it a requirement to regulate not only streets and cars, but city development in general through urban planning. It was here that the word “zone” and “zoning” came into common usage as it was adopted by city planners, making it possible to divide up complex areas into manageable units. When seeing NIZ practice through this lens, it is unsurprising that pictorial warning signs was chosen precisely because, similarly to a growing city, the NIZ regulates a complex environment where accidents are plentiful. Like an intersection, the medicine room tends to be a limited space that can quickly become crowded and loud. Studies show that interruptions cause more medical mistakes when nurses prepare medicine under these conditions. So, the NIZ serves a similar purpose as traffic signs and lights, in trying to manage a complex and volatile environment.

Another way of thinking about managing complex environments has become widespread in hospitals since the dawn of behavioral science, and that is “nudging”. Nudging is the engineering of human environments so that they gently nudge people towards certain practices. A famous example in Denmark include trashcans that say thank you for throwing rubbish into them. Nudging studies are plentiful in healthcare (Mortensen, Nordhaug, & Lohne, 2019), especially within hand hygiene compliance studies where a popular, albeit unimaginative, nudge is the poster sign that we also see in NIZ practice. Historically, nudging is especially associated with democratic states that enforce most laws socially rather than forcefully and must therefore find alternatives to incite behavioural change (Leggett, 2014). However, nudging is still a tool of power and control and represents the antonym to thinking and reflection. The introduction of nudging initiatives represents “broader issues about the changing nature of state–citizen relations. The new behavioural economics (including nudging) still offers a thin conception of human agency, and an underdeveloped sense of social structure” (Leggett, 2014, 17).

When tracing NIZ practices through the usage of signs and “zoning” it reveals, we realize that the zone is not a neutral space that only regards medicine safety, but also a politically infused space of power dynamics. This explains a peculiar dynamic in many NIZ studies where the researcher will note staff pushbacks as a limitation of the study, e.g., ”some nurses refused to continue to wear the lanyards” (Freeman, McKee, Lee-Lehner, & Pesenecker, 2013, 185). The researchers do not consider this pushback too important though, but only a question of improving “buy-in”. They seem unaware of the power dimension of their intervention and experiments in the hospital ward.

Zone Culture

Recently, an elderly woman told me in vivid detail how she experienced the German occupation of Denmark when she was only 6 years old, living in a small city at the West Coast of Jutland. The city had a small railroad station, and she and her friends used to go to the beach by crossing the railroad tracks at the station. However, when the Germans came, they occupied the railroad station and made it an off-limits zone — securing it for transportation up and down the west coast that faced the British Isles. As a consequence for the children, a grey-clad German sentry guard with a machine pistol blocked their path the beach. The first few times, the friends would go the long way around the station. However, they eventually discovered that the guard was “human” and nice enough to let children cross the tracks. The story is an example of what happened in much of the west during the 20th century as states became stronger and more complex. Centralized government interests came to dominate cities and closed of large areas for the public, not only for privatization but also for industrial and military interests — these areas came to be considered too hazardous or too critical for use a common public space. However, as the story above shows, many of these zones were not sealed off completely, but had to be negotiated by regular humans in their regular lives.

This phenomenon of industrialized societies negotiating the effects of industrial-scale zoning came to be a fundamental issue in a subgenre of science fiction known as “Zone fiction”. The first and most iconic example of Zone fiction is Tarkovsky’s film Stalker (1979) adopted from the Strugatsky brothers’ novel Roadside Picnic (1972). It was these Soviet artists who first griped with the zoning of modern society, but today we see capitalist versions of the idea everywhere in science fiction. Think only of how sci-if films tend to be structured around getting into or out of an off-limits zone. The film series The Hunger Games (2012-), also based on a novel series, come to mind, presenting the idea of some mysterious, all-powerful government controlling a zone that the protagonist must travel through and unravel. Zone fiction have a broad appeal and influence, think only of how the three-finger salute from Hunger Games have become the symbol of the people’s resistance movement against the 2014 and 2021 coup d'états in Myanmar. More contemporary examples of Zone fiction are plentiful and because “The Zone” features so prominently in the public psyche, we might take lessons from here of how to think about zones.

Taking Tarkovsky’s iconic film Stalker as a starting point, the film is about a prohibited zone called “The Zone” reminiscent of the abandoned wasteland around Chernobyl. Inside The Zone, there are supposedly debris/rubbish after aliens visiting earth (having a “roadside picnic” on earth, hence the title of the original novel) located in a room at the centre the Zone. It is believed that all your desires will be fulfilled when interacting with the mystical alien objects. A Stalker is a person who smuggles people into The Zone to interact with the magical, alien objects. The point of Stalker (and the book Roadside Picnic on which it is based) is arguably that people cannot really know or formulate their desires when they finally reach the centre. Joyssance, the constant and painful search for happiness, is here a black hole that can only be described in general terms: when the protagonist of Roadside Picnic finally reaches the alien objects, he discovers that his desires can only be formulated in the broadest sense as “Happiness for all ... Free!”. The Zone has this mythic function as a plane which people can project their dreams and beliefs. The philosopher Slavoj Žižek interprets the zone of Stalker in the same vein in his 2006 film A Pervert’s Guide to Cinema:

There is nothing specific about the Zone. It's purely a place where a certain limit is set. You set a limit, you put a certain zone off-limit, and although things remain exactly the way they were, it's perceived as another place. Precisely as the place onto which you can project your beliefs.

Tarkovsky had a similar interpretation of his work, quoted in Žižek (1999):

I am often asked what does this Zone stand for. There is only one possible answer: the Zone doesn't exist. Stalker himself invented his Zone. He created it, so that he would be able to bring there some very unhappy persons and impose on them the idea of hope.

In this interpretation, the zone is a place where an arbitrary limit is set and that therefore becomes open to interpretation. This is illuminating of NIZ practice where nurses and doctors do not necessarily interpret “No-interruption” in the same manner as researchers intended. NIZ studies rarely define the meaning of the space - neither in the article text nor to their research subjects. So, the researchers expect that staff will instantly understand what is meant by red tape or a sign. Several studies will even actively avoid questions of definition, with one curious example where a researcher would answer vaguely: “If the data collector was asked questions by the staff, she was instructed to respond with a general description of a patient safety initiative” (Anthony et al., 2010, 25). We could interpret this vagueness as the researcher’s commitment to the experiment, but in line with Zone fiction, a better interpretation might be that even the researchers do not know the full meaning of the NIZ.

Instead of defining allowed practices in the zone, studies only define the NIZ by what should not occur there (the “No-“) and that is interruptions. So, the space is only defined negatively as an off-limits space but is not communicated to staff what is meant by this limit. Studies then hope that hospital staff will interpret the word interruption on a west or sign as a warning not to correspond with the individual in the no-interruption zone. The unsurprising result is that, no-interruption zones are interpreted very differently by nurses’ and doctors’ as they bring in their own ideas about what constitutes interruptions. As one nurse explained to me during my observations: ‘The no-interruption zone is for not having patients disturb us’ even though patient disturbances are not mentioned in hospital guidelines. The openness to interpretation of the NIZ explains why the nurse had such a narrow interpretation of the Zone as a patient-free area - the space allows him to construct his idea about what constitutes an interruption.

This is a problem for researchers because not only patient interruptions lead to more error. Colleague interruptions do too. Few NIZ studies seem aware that their intervention is interpreted very differently by nurses and doctors. If we learn one thing from Stalker and other Zone fiction, it is that openness to interpretation is the default nature of an off-limits zone.


While researchers will emphasize the origin of NIZ experiments in inspiration from aviation’s Sterile Cockpit Rule, tracing the concept of NIZ reveals that the practice is connected to a particular way of regulating complex society that emerged in the beginning of the 20th century. The NIZ is especially aligned with nudging policies that leave little agency to the nurses and doctors being nudged. On the other hand, an examination of the cultural aspects of zoning reveals that zones are semantically vague power-structures that required nurses and doctors to actively interpret the zone in accordance with their beliefs. My ethnographic studies of NIZ practices in Danish hospitals confirm that nurses will actively interpret NIZ’s to suit their work task (e.g., thinking that only interruptions from patients counts as interruptions), even if this means interpreting the zone in a manner that was not intended by hospital management.


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Image credit: Sterile Cockpit Rule illustration (Qantas Flight Safety, Issue 4, Summer 2002)

Malte Lebahn-Hadidi

Malte Lebahn-Hadidi