The concept of the ‘Sterile Cockpit’ as a defence against distraction is a well known one, even well below the cruising levels of the world’s airline operations. The chances are most helicopter pilots will be familiar with it as a company Standard Operating Procedure. Not so many will know that it is in fact a formal regulation under both US Federal and EASA regulations, in the latter case under PART-ORO, and therefore non-compliance is a violation of these. The rule was first enacted by the FAA in 1981 which makes it 40 years old this year. Since then, evidence from the airline world and beyond shows that this regulation is still frequently ignored by crews. Non-compliance with the sterile cockpit rule is a very common violation.


The term ‘Sterile Cockpit’ is used to describe any period of time when crew members shall not be disturbed except for matters critical to the safe operation of the aircraft and/or the safety of the occupants. In addition, it states that during these periods of time the flight crew members should focus only on their essential operational activities. 

Unpacking this a bit, there’s really two halves to this rule, with one objective. The first half is that you shouldn’t be disturbed by anyone. The second half is that you shouldn’t do any disturbing.

Before we go on to discuss the concept in more detail, it helps to have a little background on where it came from in the first place. The rule was created in response to the crash of Eastern Air Lines flight 212 at Charlotte Douglas International, USA, in 1974. The accident investigation determined that one of the principal causes of this accident was that the pilots were distracted by an attempt to visually identify a nearby amusement park whilst setting up for final approach and flying at a low altitude. In this case (as in many others) they were both the disturbers and the disturbed, the distractors and the distracted.


The sterile flight deck procedures were published in Regulation (EU) 2015/140 as an amending regulation to (EU) No 965/2012 on air operations. The associated guidance material is AMC1ORO.GEN.110(f).

It states that:

Sterile flight crew procedures should ensure that:

  1. flight crew activities are restricted to essential operational activities; and
  2. Cabin crew and technical crew communications to flight crew… are restricted to safety or security matters.

The sterile flight crew procedures should be applied:

(1) during critical phases of flight;

(2) during taxiing 

(3) below 10 000 feet above the aerodrome of departure after take-off and the aerodrome of destination before landing, except for cruise flight, and;

(4) during any other phases of flight as determined by the pilot-in-command.

As ever, a first scan of the wording hints at the rule’s provenance in airline flight profiles but if you look more carefully its applicability is universal and straight-forward. In my opinion it is useful to boil it down even further to points (1) and (4). (Given that as the aircraft is under its own power, by many definitions taxiing is considered to be a flight phase, and approach and departure can be included into the definition of critical phase of flight). In fact, and in particularly in terms of its relevance to most kinds of rotary wing operations, we could make it even more simple, by agreeing that, sterile crew procedures should be applied, ‘on demand’.


What distinguishes the sterile cockpit concept in many helicopter flying tasks from its use in routine passenger flight sectors is that it is less of a rule based procedure. In an airline flight profile you can by-and-large apply the rule: No chitter chatter below 10,000 feet.

As a rule based procedure, the sterile cockpit is about good communication techniques and communication discipline. Most of us are aware of occasions when flight safety was compromised because crew members or passengers broke the silence, and our concentration. Although the rule is simple, well known, and easy to apply, it is also easily ignored, or overcome by our very human desire to share a thought, a sight, or get something off your chest right then and there before the moment has passed. Like many violations, not complying with it reinforces the sense that it is of little importance because most of the time it will betray no visible consequences. Most of the time.

In helicopter operations application of the concept is less rule-based and more of a skill-based procedure. Why? Because we are more likely to be interacting with the parts of the rule that require judgement, decision-making, and experience to decide how and when to apply it. Knowing when you have entered or are about to enter a critical phase of flight is not always straight-forward, can’t always be based on pre-defined flight profiles, and instead needs you to be able to interpret workload on behalf of yourself and on behalf of other members of the crew.


When many complex or concurrent tasks are performed in a short time interval, distracting events can cause errors and significant reductions in the quality of work performed. The performance of a non-safety related duty or activity when crew workload is heavy could be the critical event which precludes a crew-member from performing an essential task such as extending the landing gear. This not uncommon happening was the case in an incident in 2016 in Japan when a SAR configured AW139 landed on a beach directly next to the scene of a rescue, and high whole-crew workload distracted a crew of four from checking the gear was down before landing.

The need to assess and interpret workload is particularly true in the case of the often high tempo and multi-faceted task environment of SAR and HEMS missions. Defining critical phases of flight for an IFR transit doesn’t take as much analysis and consideration as it can do within the constantly changing risk profiles that make up the landscape of some helicopter rescues. Neither does it have the same multiplicity of unforeseeable distractions, all of which could be construed as ‘essential operational activities’. Take for example the monitoring of multiple communications networks transmitting simultaneously. R/T tends to demand a high proportion of attention to the detriment of other tasks, as well as being one of the most cognitively draining activities in the aircraft. Recognising this kind of thing contributes to your understanding of critical workload thresholds.

The sterile cockpit is about more than just communication, it is primarily about workload.


Highly effective crews tend to have a highly task-oriented communication, building in techniques such as ‘round robin’ interjections, or an information acknowledgement sequence. These kinds of advanced communication skills are developed by training and experience, and you recognise them when you see them in practice. These skills are also likely to be accompanied by an enhanced ability to intuitively understand and make judgements about the changing cognitive capacity of fellow team members.

Simply being quiet and not interrupting others is not the correct response to a call for sterile cockpit conditions. This is where the interplay with other non-technical skills such as crew monitoring come into evidence. When sterile cockpit is instigated it should be a ‘Red Flag’ warning you to tune into the workload of other members of the crew and up your rate of questioning and monitoring. It should trigger you to be on the look out for sources of distraction, and to start double checking the critical actions of other team members. It should also cause you to ask yourself whether you can contribute to sharing or distributing that workload.


In helicopter operations this is a whole crew function, and therefore semantically limiting the concept to a sterile ‘cockpit,’ in the sense that it is the domain of the pilots alone, is not helpful. That it is written this way highlights how it was conceived for a passenger jet with a closed door flight deck and a physical as well as metaphorical distance between the functions of the pilots and their crew. This compares with the different physical workspace of a helicopter as well as the important distinction of a more integrated team dynamic which is typical of helicopter crews.

During CRM training I listen to the perspectives of HEMS, SAR and firefighting helicopter teams. A question was raised recently as to whether any member of the crew could call for a sterile cockpit/aircraft. My answer was, absolutely you can. Doing so will not stop anybody on board from carrying out essential operational activities.

EASA’s regulation on sterile cockpit determines that the rule can be instigated ‘in any phase of flight’ on the judgement of the pilot in command. Whilst deferring to the ever-present authority vested in the figure of the Aircraft Commander, I don’t believe that the ability to call for a sterile cockpit is a role that should be restricted to the Pilot in Command, as the regulation would have you believe. It is not a demand for silence. Instead, it is a clear and known message to everybody else that flags up a high perceived level of cognitive demand on you or other members of the crew. It is expected to be met with an immediate response based on a known procedure and understood rationale. 

Medicalised and SAR helicopter scenarios give a perfect example of how the function of a sterile aircraft can be just as important when requested from back to front as from front to back. A crew working on a medical emergency in the helicopter cabin can be under higher workloads and pressures at different times to the pilots in the front, but the human factors at play remain the same.

In his book Peak Performance Under Pressure: Lessons from a Helicopter Rescue Doctor, Stephen Hearns describes how the relevance of a concept which he first learned from his contact with SAR and HEMS helicopters can be transferred into other high pressure environments. He has been applying it to emergency medical response scenarios, which is where it comes full circle back to SAR and HEMS aircraft. The sterile cockpit concept has a place in any high pressure, high workload environment because it is about the limits of human cognitive capacity and distraction, so why not allow it to be called for by any member of the crew that recognises when they – or anyone else – are being stretched or distracted? Investing the authority to do so in any member of the crew has the added bonus of teaching all of us to be responsible for the business of anticipating risk and empathising with the cognitive load of others.


How does the Sterile Cockpit rule appear in your Operations Manual? Unfortunately, some helicopter operators have latched on to the fixed wing application of sterile cockpit in flight phases below 10,000 feet in height, and transposed it, choosing to demand the same conditions in a helicopter below 1000 feet above ground level, and prohibiting a list of cockpit and cabin activities below that height.  This exposes the danger of an over prescriptive SOP which does not correspond to the realities of how we operate the aircraft. The result is non-compliance with a rule that effectively demands a constantly sterile environment for aircraft that rarely climb above that height. The rule quickly becomes worthless. 

When it comes to applying the concept, more than knowing what the rule says, we need to understand what it is trying to achieve. Now we can apply judgement. This is especially true in helicopter operations where the sterile cockpit requires a more subjective judgement of workload, rather than simply applying a rule about communication. Be sensitive to changing conditions of workload. Understand that anyone can demand a sterile aircraft in response to a perceived risk or distraction. And don’t be afraid to use it.


  1. An excellent article which really gets under the skin of what a ‘sterile cockpit’ should mean and how it should be used by all crew.


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