Not every duty is a flight. Standby and reserve are the states of waiting to be needed, and because waiting can be more or less restful, the rules treat them carefully and convert them into duty in specific ways.
This is general educational information, not operational, legal, or regulatory advice. Rules differ by authority and change over time. Always verify against current official sources and follow your operator's approved procedures.
What standby and reserve are
Standby, in the EASA framework, is a defined period during which a crew member is required by the operator to be available to receive an assignment for a flight, positioning, or other duty, without an intervening rest period, set out in ORO.FTL.225. EASA also defines a separate reserve in ORO.FTL.230, so under EASA standby and reserve are distinct statuses, not the same thing. In the FAA framework, reserve (14 CFR 117.21) is the status of being available to receive an assignment for a flight duty period. The terms do not map one-to-one across the two systems, so read each against the rules it belongs to; the shared idea is time spent ready rather than flying.
The reason the rules care is fatigue. An hour spent at the airport in uniform, expecting a call at any moment, is not the same as an hour at home where you might nap. So both systems distinguish the kinds of waiting and assign them to duty differently.
Standby under EASA
EASA ORO.FTL.225 sets out how standby works, and the headline distinction is between airport standby and other standby:
- Airport standby, where you must be present at the airport, counts in full as a duty period for the cumulative duty and rest rules in ORO.FTL.210 and ORO.FTL.235. It is effectively treated like working.
- Standby other than airport standby, typically at home or in suitable accommodation, is treated more leniently. 25 per cent of it counts as duty for those cumulative totals (CS FTL.1.225(b)(3)), on the basis that you have a real chance to rest. That is not "a proportion set by your operator": it is a number in the certification specifications.
Now the part that is most often got wrong, and it is worth stating flatly. Under EASA, standby does not start your flight duty period. CS FTL.1.225 says the FDP counts from the start of the FDP, that is, from the reporting time. What the standby does instead is cut the maximum FDP you are then allowed, and the two kinds of standby cut it differently:
- Airport standby. The maximum FDP is reduced by any standby time in excess of 4 hours, and the combined duration of the airport standby and the assigned FDP may not exceed 16 hours.
- Standby other than airport standby. The standby ceases when you report at the designated reporting point, not when the phone rings. If it ceased within the first 6 hours, the maximum FDP is untouched. If it ran beyond 6 hours, the maximum FDP is reduced by the standby time exceeding 6 hours. (That 6-hour figure becomes 8 if the FDP is extended by in-flight rest or split duty.) Such a standby may not run longer than 16 hours in the first place, and if it starts between 2300 and 0700, the hours between 2300 and 0700 do not count towards the reduction until the operator calls you.
So the honest summary is that being called late in a long standby is not the same as a fresh report. Not because the standby is bolted onto the front of your duty, but because it has quietly lowered the ceiling above it.
Reserve under the FAA
FAA 14 CFR 117.21 handles reserve through three types, and the one most often left out of a summary is the first:
- Airport/standby reserve. If you are required to be in a reserve status at the airport, all of that time is part of your flight duty period (117.21(b)). This is the rule that catches people out, and it belongs to the FAA, not to EASA: the FDP clock is running while you sit in crew ops, which is why the same hours of waiting cost far more here than under an EASA standby.
- Short-call reserve. You are in a reserve availability period (RAP) of no more than 14 hours, during which you can be contacted and assigned with relatively little notice. For an unaugmented operation, the RAP and the FDP together may not exceed the lesser of the Table B maximum plus 4 hours, or 16 hours measured from the start of the RAP (117.21(c)).
- Long-call reserve. The default: any reserve not designated airport/standby or short-call is long-call (117.21(a)). It gives more notice, and if the operator calls you for a duty that will begin before and operate into your window of circadian low, you must be given 12 hours' notice of the report time (117.21(d)).
The thread that runs through the FAA approach is notice: the less warning you get before flying, the more carefully the reserve has to be bounded, because the chance to be properly rested depends on knowing when you will be needed. And note that the symmetry with EASA is inexact by design. EASA airport standby counts as duty and lowers the maximum FDP; FAA airport/standby reserve counts as the FDP itself. Do not carry either rule into the other system.
A worked example
A crew member is on home standby from 0400. The call comes at 1100 and they report at 1200, so by the time the flight duty period starts the standby has run eight hours, because under CS FTL.1.225(b) a standby other than airport standby ceases when you report, not when you are notified.
Two things follow. First, 25 per cent of that standby, two hours, goes onto the cumulative duty totals. Second, because the standby ran past six hours, the maximum FDP is reduced by the two hours in excess of six. A 1200 report for a single sector would normally carry a basic maximum FDP of 13 hours under ORO.FTL.205; after the reduction this crew member has 11. The FDP itself still starts at 1200, not at 0400. What the standby took was the ceiling, not the clock.
Under the FAA, the same eight hours would be read against 14 CFR 117.21, and the answer depends entirely on which reserve type it was: an airport/standby reserve would have had the flight duty period running since 0400, while a short-call RAP would be bounded by the 14-hour and 16-hour caps instead. Different mechanisms, same intent: account honestly for how rested the waiting really left you.
From standby to a duty: a timeline
The abstract rules are easiest to see as a timeline. Take that same crew member on home standby under the EASA scheme, and follow the clock.
- 0400. Standby begins at home. From here, 25 per cent of the standby time will count as duty for the cumulative limits, on the basis that the crew member can rest while waiting.
- 1100. The operator calls with an assignment. This is the notification. It does not end the standby, and it does not start the flight duty period.
- 1200. The crew member reports at the designated reporting point. The standby ends here, at eight hours, and the flight duty period starts here. From this moment the FDP runs in the normal way, to the end of the last sector.
The question the rules answer is not "how much of the standby is added to the FDP", because none of it is. It is how much of the standby is subtracted from the maximum FDP. For a home standby the answer is the time beyond six hours, so eight hours of standby costs two hours off the ceiling. For an airport standby the answer is the time beyond four hours, and there is a hard 16-hour cap on the standby and the FDP together. Either way, a call late in a long standby leaves a shorter allowable duty than a fresh report at the same hour would.
Under the FAA the same wait can look very different. A short-call reserve crew member sits in a reserve availability period of no more than 14 hours, and the availability period plus the flight duty period are capped at the lesser of the Table B maximum plus 4 hours, or 16 hours from the start of the RAP (14 CFR 117.21(c)). An airport/standby reserve crew member, by contrast, has been inside their flight duty period since they arrived at the airport (117.21(b)). The mechanisms differ, but the timeline tells the same story in both systems: the clock that matters started before the crew member ever reached the aircraft, and the time spent waiting is accounted for, not free.
Airport standby in practice
The contrast between the two kinds of standby is sharpest in a worked case. Two pilots both begin standby at 0400, both report at 1200, and both are rostered a single four-hour sector. Eight hours of waiting apiece. A 1200 report for one sector carries a basic maximum FDP of 13 hours under ORO.FTL.205, so that is the ceiling each of them starts from.
Pilot A is on airport standby, required to be at the airport the whole time. Under EASA ORO.FTL.225 that time counts in full as a duty period, so eight hours are on her cumulative duty totals before she reports. Her flight duty period, though, still begins at 1200. What the standby costs her is the ceiling, and under CS FTL.1.225(a) it costs her twice over:
- the maximum FDP is reduced by the standby time in excess of 4 hours, so 13 hours becomes 9; and
- the airport standby and the assigned FDP together may not exceed 16 hours, and 8 are already spent, so the FDP may not exceed 8.
The lower of the two binds. Pilot A has 8 hours of flight duty period, not the 13 a fresh 1200 report would have carried, and her day measured from the start of standby can run to 16 hours.
Pilot B is on home standby for the same eight hours. Only 25 per cent of it, two hours, lands on her cumulative duty. Her FDP also starts at 1200, and her maximum is reduced only by the standby time beyond 6 hours, so 13 hours becomes 11.
Same eight hours of waiting, same four-hour sector, and Pilot B walks to the aircraft with three more hours of legal duty than Pilot A. Now notice where the rules do not bite. Had both standbys ended at the six-hour mark instead, Pilot B's maximum FDP would have been untouched at 13 hours, because the home-standby reduction only starts working beyond six. Pilot A's would still have been cut: the 4-hour trigger takes 2 hours off, giving 11, and the 16-hour combined cap then binds harder at 10. This is the detail worth carrying away: the home-standby reduction has a six-hour dead zone, the airport-standby one has a four-hour dead zone, and the combined cap is always watching regardless.
The practical reading for anyone studying a roster is that an airport standby is close to working and should be treated as such when judging how much duty is left, while a home standby is more protected. The broader habit to build is to ask, first, which kind of waiting a standby is, because that single fact decides how much flying the rules will still allow. And under the FAA, ask a different question first: which of the three reserve types you are on, because an airport/standby reserve has had your flight duty period running since you arrived (14 CFR 117.21(b)) - a harsher rule than anything in the EASA standby scheme, and precisely the rule people wrongly attribute to EASA.
Common pitfalls
- Thinking EASA standby starts your FDP. It does not. Under EASA the flight duty period starts at the reporting time, and the standby lowers the maximum instead. The rule that puts you inside your FDP from the moment you reach the airport is the FAA's airport/standby reserve, 14 CFR 117.21(b).
- Treating all standby as equal. Airport standby counts in full as duty; only 25 per cent of a home standby does.
- Assuming a short standby is free. Airport standby starts cutting the maximum FDP beyond 4 hours, home standby beyond 6, and airport standby plus the FDP is capped at 16 hours whatever the table says.
- Thinking the FAA has two reserve types. 14 CFR 117.21 has three: airport/standby, short-call and long-call.
- Assuming reserve is time off. Short-call reserve is a bounded, protected duty state, not free time.
- Ignoring the operator scheme. The approved scheme fills in the detail and can be more restrictive than the baseline.
In Pilot EFB
Pilot EFB's flight time limitation calculator accounts for standby and reserve periods when it works out your duty, so a standby that converts into a flight is reflected in your totals rather than being lost. It is a planning and awareness aid built to help you see the picture, not a compliance system: how your standby or reserve converts to duty and what flight duty period you are then allowed is governed by your operator's approved scheme and the current regulation. Pilot EFB is not a certified Electronic Flight Bag. Saved roster data stays available offline; pulling a fresh roster needs a connection.