How to read a NOTAM
The anatomy of a domestic NOTAM, what FDC means, the contractions worth memorising, and the timing traps that make a pilot read a future closure as a current one.
A NOTAM reads in a fixed order: series and number, the location it applies to, the condition in standard contractions, then the effective window in UTC. The condition is usually obvious once you know a dozen abbreviations. The window is what people get wrong, because a NOTAM can be published days before it takes effect.
A Notice to Air Missions is a filed notice about a temporary condition: a closed runway, a navaid out of service, a crane near the approach path, restricted airspace. Checking them is not optional. Under 14 CFR 91.103 a pilot must become familiar with all available information concerning the flight, and NOTAMs are named in the advisory material behind it.
The anatomy of a domestic NOTAM
- Series and number. 08/002: the second NOTAM filed at this facility in August. It is a filing reference, not a priority.
- Affected facility. LVK: what the notice applies to. Usually the airport, sometimes a navaid or an airspace boundary.
- Condition. RWY 25R ALS U/S: runway 25R approach lighting system unserviceable. This is the news.
- Effective window. 2608071530-2608072000: from 2026 August 07 at 15:30 UTC until 20:00 UTC. Always Zulu.
Domestic and FDC are two different things
A domestic NOTAM comes from the airport or facility and describes a physical condition. An FDC NOTAM comes from the FAA Flight Data Center and is regulatory.
The distinction matters because it tells you who decided and what kind of thing you are reading. A domestic notice tells you a taxiway is closed or a light is out. An FDC notice amends an instrument approach procedure, changes published minimums, or establishes a temporary flight restriction. A TFR is always FDC, which is worth remembering the next time somebody says they checked NOTAMs and only looked at the airport list.
The contractions worth knowing
NOTAM text is written in a controlled vocabulary so it can be filed and parsed consistently. You do not need all of it. These carry most of the meaning:
| Contraction | Means |
|---|---|
| CLSD | Closed |
| U/S | Unserviceable, out of service |
| RWY / TWY | Runway / taxiway |
| ALS, MALSR, REIL | Approach lighting, runway end identifier lights |
| PAPI / VASI | Visual glide slope indicators |
| AD | Aerodrome, the airport as a whole |
| OBST | Obstruction, usually with a height and position |
| WIE | With immediate effect |
| UFN | Until further notice |
| PERM | Permanent, the chart has not caught up yet |
| EST | Estimated end time, the issuer may revise it |
| DLY | Daily, followed by a time range |
| EXC | Except |
So TWY J CLSD TO ACFT WINGSPAN MORE THAN 50FT EXC XNG reads as: taxiway J
is closed to aircraft with a wingspan over 50 feet, except for crossing it.
The five traps
- A published NOTAM is not necessarily an active one. This is the big one. Scheduled closures are routinely filed days ahead. A notice with a start time tomorrow night is telling you about tomorrow night, not about now. Read the window before you read the condition.
- EST means the end time is a guess. An estimated end is the issuer's best case. Work is regularly extended, and the notice is amended rather than expiring on schedule. Never plan an arrival for five minutes after an EST end.
- A schedule line overrides the window. A notice can be effective for
a month and only active for part of each day.
DLY 1100-0001inside a long window means the condition applies daily between those hours, not continuously. - Volume hides the important ones. A large airport can carry well over a hundred active notices, most of them cranes and routine obstacles. The closed runway is in there somewhere. This is why every serious NOTAM view sorts by what changes a decision rather than by filing order.
- Times are UTC, and the date is in the number. 2608071530 is year 26, month 08, day 07, at 15:30 Zulu. Reading it as a local time is how a pilot arrives during the closure they checked for.
Where SkyReady fits
Every SkyReady airport page shows the active NOTAMs for the field, grouped by what they affect and ranked by whether they change a go or no go decision, so a runway closure is not buried under forty crane notices. The dedicated NOTAM page for each airport also lists the complete set with absolute Zulu windows and the raw text, because the raw text is the only version with everything in it.
None of that replaces an official briefing. A NOTAM view is a planning aid; the regulatory source is the FAA NOTAM Search service or a briefing from an approved provider.
NOTAM FAQ
What does NOTAM stand for?
Notice to Air Missions. It was Notice to Airmen until 2021, which is why both expansions are still in circulation.
Am I required to check NOTAMs?
Yes. 14 CFR 91.103 requires a pilot in command to become familiar with all available information concerning that flight before departing, and NOTAMs are part of that information for any flight not in the local area.
How long does a NOTAM stay active?
Anywhere from minutes to months. Many carry an explicit end time, some read UFN (until further notice), and PERM marks a permanent change that has not yet reached the charts. Cancellations are filed separately, so a notice can also disappear before its stated end.
What is a TFR?
A temporary flight restriction, published as an FDC NOTAM. TFRs cover things like presidential movement, stadium events, firefighting and disaster areas. They are regulatory airspace, not advisory, and they do not appear in an airport's own notice list unless the airport is inside one.
Sources: 14 CFR 91.103; AIM 5-1-3; FAA JO 7930.2 (Notices to Air Missions); ICAO Annex 15. Educational material; brief the current notices, not an example.