Legal Is Not the Same as Fit for Duty

The Night I Called In Fatigued

It was snowing hard in Denver. I was flying a 737 to Las Vegas, and nothing about the night was going to be quick. We sat for deicing. Then we sat again, waiting for the runway to be plowed. Anyone who has flown in winter knows that kind of night. You’re watching the holdover time, watching the snow, watching the clock, and none of it is in your control. By the time we got airborne we were about three hours late.

Las Vegas was supposed to be a turn. The plan was a redeye to Newark, landing at about 0530 Eastern. With the delay, that arrival was now going to be closer to 0800.

And it was still legal. Because we had reported early in the evening, the Part 117 tables allowed a longer duty period than a trip reporting later in the evening, and even with the delay the trip fit inside it.

Add it up, though. Hours of winter operations that kept me wound tight the whole time, three hours of delay on top of that, and then an all night flight right through my window of circadian low, which Part 117 defines as 0200 to 0559, the hours when the body is built to be asleep. Stress like that doesn’t stay at the gate. It wears you down the same way lost sleep does, and you carry it onto the next flight. Legal, yes. Fit for duty, no.

So when we got to Las Vegas, I called scheduling and told them I was fatigued.

I was released from the trip and given a place to rest. Afterward I wrote a report explaining why I made the call, and the company’s review deemed it an operational fatigue event.

What the rule actually says

Most people know Part 117 as a set of tables: report time, number of legs, maximum flight duty period, minimum rest. Those numbers matter, but they aren’t the heart of the rule. Section 117.5 is, and the FAA spells out what it means in Advisory Circular 117-3, Fitness for Duty.

The AC defines fit for duty as being “physiologically and mentally prepared and capable of performing assigned duties at the highest degree of safety.” Notice the word mentally. That’s a higher bar than legal, and it’s where stress counts.

The responsibility runs both ways. The airline has to give me a meaningful rest opportunity. I have to show up rested, and when I sign the flight release, I’m attesting that I’m fit for duty. And once a pilot reports too fatigued, that pilot is done until rested. Section 117.5(b) says the airline may not assign that pilot to a flight duty period, and the pilot may not accept one. When it happens partway through a trip, as it did for me, the AC says the airline must remove that pilot and replace him or her with one who is fit for duty.

The tables tell you what’s legal. They can’t tell you how the day actually went. Only the pilot in the seat knows that, and the rule gives that pilot the authority to say so.

What to look at when fatigue is in question

When fatigue comes up after an incident, the first thing everyone checks is whether the crew was within limits. Usually they were. That’s where the real questions start. What did the day actually look like? How long had the crew been awake? How much weather, deicing, and delay did they work through before the flight in question, and how much stress came with it? Where did that flight fall against their body clock?

Then look at the company’s fatigue policy, because every airline handles this differently. What happens when a pilot calls in fatigued? Is the pilot released and given protected rest? Is there a report and a fair review of whether the fatigue was operational or personal? Does the pilot lose pay if the review goes the other way? The answers tell you whether calling in fatigued is a real option on that property, or one that only exists on paper.

Why It Matters

Fatigue rarely shows up by name in an accident report. It shows up as a missed callout, a slow response, a decision that doesn’t make sense in hindsight. A crew can be completely legal and still be in no shape to fly, and the rule counts on the pilot to speak up. Whether that pilot speaks up depends on whether the company makes it safe to do so.

Legal tells you what the company can ask of you. Whether you’re fit for duty or not, Part 117 leaves that up to you.

Further reading: FAA Advisory Circular 117-3, Fitness for Duty