Why We Do
the Things We Do

Ask a pilot why we follow standard operating procedures and the answer comes straight away: so that everyone operates the same way. Any two pilots can fly together for the first time and know what to expect from each other. The procedures stop us busting altitudes, forgetting to configure the aircraft, or flying an approach on the wrong altimeter setting.

All of that is true. It is also only half the answer. The other half explains almost everything else we do on the flight deck, and it is worth understanding, because it changes how we treat the routine parts of the job.

Under Pressure, We Fall Back on Habit

When a non-normal situation develops, the human brain does what it has always done under stress. Attention narrows. Working memory, the capacity we use to think something through, shrinks just when it is needed most. What remains available, almost automatically, is whatever we have practised so often that it no longer needs thinking about.

That is the real purpose of the routine. The habits we build on ordinary flights are the ones we will rely on when the flight is no longer ordinary. Nobody can decide, at the moment an engine fails or the weather closes in, to start communicating clearly or managing the automation well. Either those habits are already there, or they are not.

Seen this way, almost everything we do has two purposes: the obvious one, which serves the normal flight, and the deeper one, which prepares for the non-normal. The examples below run across all nine core competencies.

Standard Operating Procedures

SOPs standardise the operation and catch the everyday errors: the altitude bust, the missed configuration, the wrong altimeter setting. On a normal day that is reason enough. But we follow them with the same discipline on the easiest sector of the year because of what they become: patterns so familiar that they still run when the operation strays from the norm.

A crew that has flown the procedure the same way hundreds of times does not need to think about the basic sequence when a non-normal occurs. That frees the little capacity they have left for the problem itself.

Calling the Mode Annunciator

On a normal flight, announcing every mode change can feel like a formality. The aircraft is doing what both pilots expected, and both can see the mode annunciator.

The reason we do it is the day the pilot monitoring becomes busy: running a checklist, talking to air traffic control, handling the cabin crew. At that point the pilot monitoring is no longer watching the trajectory, and the pilot flying, by calling the modes as they change, keeps them informed of what the aircraft is doing. Situational Awareness is maintained across the whole crew, not just the pilot with spare eyes. That only works if the calls are already a habit. A pilot who calls modes only when things are going wrong will stop calling them at exactly the moment they matter.

Standard callouts work the same way. "One hundred above" and "minimums" are not for the pilot flying, who can see the altitude. They are called every time so that a missing call stands out. The absence of the expected word is often the first sign that a colleague has become fixated, overloaded or, rarely, incapacitated.

Checklists

A checklist confirms that switches are set and actions are complete. It also does something less obvious: when the workflow is disrupted, by a late change or an interruption, it slows us down and brings us back to a known point.

But the deepest reason for using checklists diligently, every time, is the feeling it creates. A pilot who always completes the checklist at the same point, in the same way, notices when it has not been done. Something feels wrong before they can say exactly what. Together with consistent SOPs, that instinct is one of the most valuable safety mechanisms we have, and it only exists if the routine has been followed so consistently that a missing step registers.

Communication

Full read-backs on a quiet frequency. When the frequency is quiet and the clearance is routine, a full read-back can seem unnecessary. We do it so that, on a congested frequency, with an unexpected clearance, the full read-back happens automatically and catches the error.

Briefing the routine arrival. The routine part of the brief is not the point. The brief is where the go-around, the diversion and the "what if" are decided in advance, while there is time. It also gives the other pilot an open invitation to challenge before anything has gone wrong. A crew that briefs properly on every arrival has a Shared Mental Model ready on the day it is needed.

Saying the plan out loud. "We're going to be high on this, I'll use the speed brake." It takes a few seconds on a normal day and keeps the Shared Mental Model current while there is time. On a difficult day, the habit means the plan is shared without anyone having to remember to share it. See Communication.

Leadership and Teamwork

Effective teams make normal operations run smoothly. That is a good enough reason to build them. But the real reason is that the way a crew works together becomes its habit, and when a challenging situation arises, effective teamwork and communication remain the norm and carry the crew through safely. A crew does not become a team in the middle of a non-normal. It is either already one, or it is two individuals managing alone.

Inviting challenge on small things. "Let me know if I'm rushing this." It costs nothing on an easy sector, and it is exactly what makes the other pilot willing to speak up on the day it matters. Authority gradients are flattened in advance, not in the moment.

Debriefing uneventful flights. A few minutes at the end of an ordinary day, talking about what went well and what could have gone better, makes open feedback normal. After a genuinely difficult flight, the conversation is then already safe to have. See Leadership and Teamwork.

Workload Management

Preparing the arrival early. Loading and briefing the approach in the cruise looks like tidiness. It is really about banking spare capacity: the runway change, the holding, the failure all arrive into a flight deck that already has room for them.

Protecting the critical phases. Keeping the flight deck sterile on the easy days stops distraction becoming normal before the day it cannot be afforded. See Workload Management.

Flying the Aircraft

Hand-flying when conditions and procedures allow. The skill has to exist before the day the automation drops out. It is far easier to keep a skill current than to rebuild it in the middle of a non-normal.

Choosing the level of automation deliberately. Leaving the automation as it is because it is working is easy. Deliberately choosing the right level for the situation, and stepping down when it is not doing what you want, builds the reflex that recovers from mode confusion quickly when it matters. See Flight Path Management, Manual and Flight Path Management, Automatic.

Monitoring as if you were flying. In a quiet cruise, the pilot monitoring keeps tracking the trajectory, the energy and the plan. The habit of active monitoring has to exist before it is needed, and it is built on the days when nothing seems to need monitoring.

Decisions

Knowing your alternate and your diversion fuel on every flight. On most flights it is never needed. On the day it is, the decision is already half made, because the numbers and the options were in your head before anyone asked.

Using a structured model on small problems. Running a delay or a minor defect through TDODAR, or whichever model your operator uses, feels like overkill. It is what makes structured decision making natural when the stakes are high. See Problem Solving and Decision Making.

Treating the go-around as a normal outcome. The go-around itself is rarely the hard part. The hard part is deciding to do it. Treating it as an expected option on every approach, briefed and ready, removes the reluctance before it can form.

Knowledge and Fitness

Reviewing memory items and the QRH on a quiet sector. Not to pass the next check, but so that recall still works when adrenaline has taken half your working memory. See Application of Knowledge.

Arriving rested and fit for duty. It is not for the routine day. It is for the diversion at three in the morning.

The walkaround that finds nothing. Nine hundred and ninety-nine times out of a thousand, it finds nothing. The habit exists for the thousandth. See Professionalism.

The habit	On a normal day	On the day it matters
Following SOPs	Standardisation; catches everyday errors	The basic sequence runs without thought, freeing capacity for the problem
Calling the modes	Confirms what both pilots can see	Keeps a busy pilot monitoring aware of the trajectory
Checklists	Switches and actions confirmed	Slows a disrupted workflow; a missed step "feels wrong"
Briefing	A tidy, predictable arrival	The go-around and diversion are already decided
Inviting challenge	A relaxed flight deck	The other pilot speaks up when it matters
Early preparation	A calm descent	Spare capacity for the unexpected
Diversion figures	Rarely used	The decision is already half made

Drift: The Same Mechanism in Reverse

Habits work in both directions. The instinct that tells us something feels wrong is built by doing things properly, consistently. It can be dismantled the same way.

A small shortcut on a normal day does no harm. The checklist is read from memory, the brief is cut short, a callout is skipped because both pilots could see the altitude. Nothing happens, so the shortcut becomes acceptable, then normal, then simply the way it is done. The sociologist Diane Vaughan called this the normalisation of deviance. It is rarely a single decision. It is a slow drift, and on the day the operation does stray from the norm, the shortcut is what the crew falls back on.

Standards Are Contagious

Why should an individual pilot strive for high standards? Not to shine at a simulator session or a line check. The real reason is that standards spread. A pilot who prepares thoroughly, calls the modes, briefs properly and invites challenge raises the standard of everyone they fly with, often without saying a word about it.

The opposite is equally true, and it is the more important half. Low standards inspire low standards. A shortcut taken in front of a new colleague teaches them that the shortcut is acceptable. Every pilot is, whether they intend it or not, a model for the next one.

Every Normal Flight Is a Rehearsal

None of this makes the routine more exciting. It makes it more meaningful. The mode call on a clear day, the full read-back on a quiet frequency, the brief for an approach you have flown a hundred times: each one is a repetition of the habit you will need when the day is no longer normal.

That is also why development has to happen on the line, flight by flight, rather than only in the simulator. Habits are built by repetition in real operations. A few deliberate minutes on each flight, focused on one behaviour and reflected on afterwards, is how the routine becomes the rehearsal.

Frequently Asked Questions

Why do pilots follow SOPs so strictly on routine flights?

Standard operating procedures standardise the operation and catch everyday errors such as altitude busts, missed configuration and wrong altimeter settings. The deeper reason is that under pressure pilots fall back on habit. Following SOPs consistently on routine flights makes them automatic, so they still run when a non-normal situation develops and frees capacity for the problem itself.

Why do pilots call out mode changes on the mode annunciator?

Calling mode changes keeps both pilots aware of what the automation is doing. Its most important use is when the pilot monitoring becomes busy with a checklist, air traffic control or the cabin: the pilot flying's calls keep them informed of the aircraft's trajectory. It only works under pressure if it is already a habit on normal flights.

What is normalisation of deviance in aviation?

Normalisation of deviance, a term coined by the sociologist Diane Vaughan, describes how small departures from procedure become accepted when nothing goes wrong. A shortcut that causes no harm becomes normal, then the standard, and is what a crew falls back on when the operation does stray from the norm.

How can pilots build habits that hold up under pressure?

By repeating them deliberately on normal flights. Habits are formed in real operations, flight after flight. Focusing on one behaviour at a time, practising it on the line and reflecting briefly afterwards turns routine flying into rehearsal for the non-normal.