“Fit to Fly?” Where Do You Draw the Line?

This is probably the shortest question you’ll answer all day.

But the answer can have consequences that go far beyond the briefing.

“Are you fit to fly?”

We hear it every morning (or evening) before a flight.

Most of us answer almost automatically, why else would you be briefing – right?

But after hearing that question hundreds (or even thousands) of times, it’s easy to stop thinking about what we’re actually being asked.

Every “fit to fly” decision means turning a sliding scale into a simple yes or no.

It’s a judgement call, and it can be one of the most subjective ones we make as pilots.

Flying in different companies and operational cultures has taught me one thing:

We don’t all draw the line in the same place.

So where should we draw it?

How do we recognise when we’re genuinely fit to fly… and when we’re simply convincing ourselves that we are?

Let’s take a look at where that line really sits.

👀 What Does it Mean to You to Be “Fit to Fly”?

If I casually ask if you’re ‘fit to fly’ during our brief, what’s the first thing that comes to mind?

The fact you’re in the building, next to me, about to go fly, suggests the answer will be ‘yes’.

It’s tempting to think that we’re just paying lip service to whatever the checklist says here.

After all, we’re here to complete a day of flying, we wouldn’t have entered our cars this morning to drive to the airport if there was a point where we thought “I am not fit to fly”.

The problem with this is that the expectation is a resounding “YES”.

Expectations can result in perceived pressure, and pressure can result in decisions that aren’t grounded in what’s safe, but in what’s convenient.

We’re also dealing with the fact that what’s fit to pilot A is unfit for pilot B (and vice versa).

I’ve seen pilots come through the door with a sore throat, colds, or visibly not well. While others call in sick when they’re “a bit run down”.

The answer will always be subjective, and only you can decide on what “fit” means in the context of being able to complete your duties safely.

Yes, we can run an IMSAFE checklist, but even those items can be interpreted in different ways.

What’s enough sleep, 5 hours, 6 hours? What if you only fly that morning, what if it’s a whole day of flying, or the start of a nightshift? Where is the line?

Only you know.

Don’t let my assumptions or expectations, change your decision on your fitness to fly!

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🔄 How Cultural Differences Change the Threshold

Mixing professional cultures is where things can start to get a little messier sometimes.

In HEMS, we have medicine and aviation intersecting, and it didn’t take me long to realise that people in the medical industry have VERY different perspectives when it comes to taking care of fatigue, wellbeing, and the general attitude towards fitness for duty.

This isn’t a critique, just an observation.

Some studies show that the healthcare industry is starting to adopt practices and cultural norms from the aviation industry.

Things like FTL’s, medical exams, and cultural factors play a huge role in how we got where we are in aviation, and how we think about being fit to fly.

It forces a certain mindset that makes us take our health seriously. Without those factors, it would be interesting how much different aviation culture would be.

This focus on health, also has some side effects, as we’ve previously discussed here:

Fit to Fly? Why so Many Pilots Hide their Physical and Mental Health Struggles

I’ve worked with doctors who would make plans straight after a nightshift. While most pilots would block out their day for a full sleep session to recover.

These philosophies clashed in an environment where pilots could be seen as “precious” and “difficult”, and doctors and paramedics as “pushing on”.

These observations are entirely subjective of course, but it presented CRM challenges, as well as differences in what was considered “fit to fly”.

This can be extrapolated to other areas where the expectation of “getting on with it” caused issues for those who were more risk averse.

Managing this can be difficult when there is no cohesive culture of “this is how we do things here”.

Anyone in a profession where industries meet that involve nightshifts and safety critical operations, will likely at some point come across this.

🚨 How to Manage the Threat of: “I’m Fine”

Let’s say you’ve managed to get away with doing a full night of sectors while having a cold or even feeling a fever coming.

This can now create a loop where you think “I can perform fine while not my best”.

But “fine” and “not my best” are slippery slopes.

So what can you actually do to make sure you don’t keep moving the line of “I’m fine” and “not my best”?

When does fit become no longer fit?

Again, only you can answer this, but it’s worth reflecting on the fact that you’re turning a sliding scale of “fitness” into a binary decision.

So the line has to be somewhere.

Some people stop performing well when distracted by dealing with an upcoming cold.

Others are not as “affected”.

Pre-Define your line

Don’t decide “fit or not” in the crew room.

Decide it when you’re objective.

For instance:

🔸 “< 5 hours sleep = no fly”
🔸 “X or Y fever symptoms = no fly”
🔸 “X amount of consecutive days of fatigue after night shifts = no fly”

This removes real-time rationalisation, which is where most bad calls happen.

Use trends, not moments

One “bad night” might be manageable.

Three in a row? Different story.

Mitigation:

🔸 Track sleep (even loosely)
🔸 Ask: “Am I declining compared to yesterday?”

Performance degradation is usually gradual, not binary.

Flip the scenario

Classic cognitive forcing strategy:

“If another pilot showed up in my exact state… would I be comfortable flying with them?”

This bypasses ego and normalisation.

Separate legal from safe

You can be:

🔸 Within your FTL scheme
🔸 Medically valid
🔸 Technically compliant

…and still not safe.

This is where many professionals hide:

“I’m legal, so I’m fine.”

That’s a bit of a compliance trap, not a safety margin.

Call out cultural drift early

If the norm becomes:

🔸 “Everyone pushes through”
🔸 “Calling in sick is frowned upon”

You’re no longer making an individual decision, you’re operating inside a shifted baseline.

Mitigation:

🔸 Verbalise it
🔸 Challenge it early, not after something you regret doing

💭 Conclusion

The tricky thing about “fit to fly” is that no one else really knows where your line is.

And over time, it’s very easy to start nudging it.

A slightly worse night of sleep.
A bit more fatigue than last time.
Feeling “not your best”… but still “fine”.

Until one day, “fine” is nowhere near where it used to be.

That’s the part that catches people out. Not a single bad decision, but a series of small, reasonable ones that slowly shift what feels acceptable.

So maybe the question isn’t just “am I fit to fly?”

It’s also:

“Am I still holding the same standard… or have I quietly moved it?”

Ready to learn from real aviation decisions, mistakes and challenges? Get our latest Notes from the Cockpit sent straight to your inbox, twice a month ⤵️