Eyrix — Blog

EASA FTL in practice: the rest and duty limits your roster has to respect

Flight Time Limitations (FTL) are the part of a crew roster you cannot negotiate. Under the EASA rules — Regulation (EU) No 83/2014, Part-ORO Subpart FTL — a duty that exceeds a limit isn't a scheduling preference you've overridden; it's a flight that can't legally operate. This is a plain-language map of the limits a roster has to clear. It is not legal advice: your approved OM-A and the current regulation always govern, and several limits vary with acclimatisation, augmented crew and approved variations.

Flight Duty Period (FDP)

The FDP runs from report time to the end of the last sector. The basic maximum for an acclimatised crew starting in the daytime window is around 13 hours, and it shrinks from there: every sector beyond the first cuts into it, and so does starting in — or working through — the small hours. A roster that stacks a fifth or sixth sector onto a duty that already started early can cross the line without any single leg looking unreasonable.

The Window of Circadian Low (WOCL)

The WOCL — roughly 02:00 to 05:59 — is when human alertness is lowest, and FTL treats duties that encroach on it more strictly, reducing the allowable FDP. A duty that begins late and runs into the WOCL is not the same as the identical block of hours flown in daylight, even though a spreadsheet would show the same duration.

Minimum rest

Rest is defined relative to the duty it follows. At home base, the minimum rest is at least as long as the preceding duty period or 12 hours, whichever is greater; away from base, at least as long as the preceding duty or 10 hours, whichever is greater. The consequence for planning: you cannot check rest by looking at a single day. It depends on the duty before it.

Cumulative limits

On top of the daily picture sit rolling ceilings — duty hours capped over 7, 14 and 28 consecutive days (broadly 60 / 110 / 190 hours), and flight hours capped at 100 in 28 days, 900 in a calendar year and 1,000 in any 12 consecutive months. These are the limits a manual roster misses most often, because they can only be seen by summing across weeks — exactly the view a grid of cells doesn't give you.

Why a spreadsheet can't hold this

Every limit above depends on context a single cell can't carry: what the previous duty was, when it started relative to the WOCL, how many sectors it held, and what the running 7/14/28-day totals already are. A planner can track this by hand — but it's the first thing to slip when a standby crew steps in under pressure. This is the same reasoning that makes a manual crew roster expensive: the rules are knowable, but not checkable by eye at the moment the assignment is made.

A scheduling engine models FTL as hard constraints and re-checks them on every assignment — rest against the preceding duty, FDP against sectors and WOCL, and the rolling cumulative totals — so an illegal roster is rejected before it's published, not discovered at the gate. A simplified rest-and- duty constraint is a sound place to start; the full EASA FTL engine, with every variation and approval, is a domain of its own to grow into.