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The Top 7 Things You Need to Know About NOTAMs

May 1, 2020

Having landed here you may be a seasoned AvGeek who already knows everything there is to know about NOTAMs and you’re interested in someone else’s take on the topic.

Having landed here you may be a seasoned AvGeek who already knows everything there is to know about NOTAMs and you’re interested in someone else’s take on the topic. Maybe you’re a new drone owner and you’ve realized that you need to access “NOTAM” data in order to fly your shiny new toy safely. Or perhaps you’re an aviation enthusiast wanting to grow your aviation data knowledge. We’re all here to read about the same thing: NOTAMs. What are they? What is considered a NOTAM? How do you access them? Who uses them? What is a NOTAM?

More information on Cirium’s NOTAM solutions

A NOTAM is the abbreviated name for ‘A Notice to Airmen.’ According to the FAA, a NOTAM is a notice containing information (not known sufficiently in advance to publicize by other means) concerning the establishment, condition, or change in any component (facility, service, procedure of, or hazard in the National Airspace System) the timely knowledge of which is essential to personnel concerned with flight operations. Basically, a NOTAM is a notification from an official body alerting airspace users to hazards along their route, both in the air and on the ground. This could be a closed taxiway, a notification about construction cranes or maintenance on a navigation aid. There are a number of different types of NOTAMs, which are detailed below.

What are the different types of NOTAMs?

There are a number of different types of NOTAMs within aviation. Some are mandatory or regulatory in nature, others advise pilots of a closed airspace, or even alert airports and airlines about a nearby flock of birds. Here’s a list of different types of NOTAMs:

  • Trigger NOTAM: issued to “alert” people of changes to the Aeronautical Information Publication (AIP), which is a local “rulebook” for each country. AIPs are kept up-to-date by regular revision on a fixed cycle. For operationally significant changes in information, the cycle known as the AIRAC (Aeronautical Information Regulation And Control) cycle is used: revisions are produced in chart publication cycles: every 28 days (single AIRAC cycle) or every 56 days (double AIRAC cycle). The intention of Trigger NOTAMs is to highlight the coming into effect of permanent or temporary changes to the AIP, and it normally includes brief descriptions of the changes, the effective date and times, and the identification of the amendment or supplements of the AIP.
  • FDC NOTAM (Flight Data Center NOTAM): FDC NOTAMs are regulatory in nature, they must be followed, much like the rules of the road when driving. For example, you cannot go faster than the speed limit on the highway and if you do you can get a ticket. In aviation there are required altitudes, speeds, waypoints etc. you MUST follow. Examples would be minimum crossing altitudes on an arrival or missed approach altitudes on instrument approach procedures – both these altitudes are regulatory and must be followed. However, sometimes these altitudes need to be changed in between the chart publication cycle (28 or 56 day AIRAC). When that happens an FDC NOTAM is issued. The FDC NOTAM would contain the regulatory change in the procedure such as the updated minimum altitude.
  • TFR (Temporary Flight Restrictions): TFRs are a type of FDC NOTAM which must be abided by and are regulatory in nature. They are a restriction on an area of airspace due to the movement of government VIPs, special events, natural disasters, or other unusual events within airspaces, meaning that an aircraft cannot fly through the TFR area and must change its flight path to avoid it.
  • BIRDTAM (Bird NOTAM): BIRDTAMs advise airspace users of a passage of a nearby flock of birds through an airspace. A flock of birds can have significant consequences on an aircraft if one gets caught in an engine. For example, when pilot Chesley Sullenberger had to glide US Airways Flight 1549 to land in the Hudson River in New York City in 2009, saving everyone on board, it was because the plane was struck by a flock of geese in both engines.
  • SNOWTAM (Snow NOTAM): A SNOWTAM is a NOTAM which affects an aerodrome and will be issued to notify users of the presence of, or the removal of, hazardous conditions due to snow, ice, slush or the resulting standing water on the runways, taxiways and aprons of the aerodrome. A SNOWTAM is valid for 24 hours and a new one will be issued whenever there is a significant change in conditions.
  • ASHTAM (Ash NOTAM): An ASHTAM advises users of an operationally significant change in volcanic ash or other dust contamination which can affect an airspace and aircrafts flying through them. An example of this is the eruption of the Icelandic volcano Grimsvotn in 2010, which completely closed European airspaces for a week in April, causing worldwide disruption with over 100,000 flights cancelled.
  • Class I NOTAM: Class I NOTAMs are normal NOTAMs that are issued via telecommunications.
  • Class II NOTAM: These are normal NOTAMs that are not issued via telecommunication. Instead, they are published in the chart publication cycle which is updated every 28 days.

Who needs access to NOTAMs?

Pilots are required to review all NOTAMs affecting their flight route before take-off.

NOTAMs are a part of a pilot’s Flight Bag, which is a set of documents pilots are required to have before their aircraft sets off on its planned route (it also includes various operating manuals, navigational charts etc).

How do NOTAMs apply to Navigational Charts?

When it comes to navigation there are many different types of charts/procedures that are used by and published for pilots. Examples include Terminal Area Charts, Sectional Charts, Departure Procedures, Standard Terminal Arrivals, En Route Low Altitude, En Route High Altitude and Instrument approach plates to name just a few. They are usually published on a 28 day cycle and changes are incorporated into newly published charts. However, there are times when issues occur that must be relayed to the users of these products immediately. They are often safety related and can include changes to routes, altitudes, speeds, obstructions, etc (anything published on the chart). When this happens a NOTAM is issued. Most of the time it is an FDC NOTAM because it is regulatory in nature, making a change to a published piece of information.

Take for example the Instrument Approach Procedure at KORD (correct at the time of writing):

KORD-RNAV-GPS-RWY-27R Chicago Ohare Navigational Chart issued via NOTAM

The image to the right shows RNAV (GPS) RWY 27R approach for Chicago O’Hare Airport. The yellow oval highlights the required visibility a pilot needs to land on the Runway (2400 feet visibility. They drop the last two zeroes)

As mentioned, the approach plate is current at time of writing, meaning that it can be legally used for navigation. However, there is a change to the required visibility which is also currently published by the FAA via an FDC NOTAM:

Notice the approach procedure below, this NOTAM changes the required visibility from 2400 feet to the new visibility of 1800 feet. The end date is PERM (permanent). This means that the change to the procedures is permanent and once a new chart is published on July 28, 2017 (highlighted via the green box on the KORD approach plate), it will be published on the approach plate, at which point there will no longer be a need for the FDC NOTAM to be published through the NOTAM manager.

Chicago NOTAM for visibility

Who issues NOTAMs?

NOTAMs such as runway obstructions, closed airspaces etc are submitted by the relevant authority (i.e. aerodrome, ANSP, military or Aviation Authority). The general public cannot submit the official NOTAM, instead they can advise the local Flight Service Station (FSS) of a special event. An example would be skydiving. A local skydiving company would call the FSS and notify them of the time and location of the skydiving activity. From there the FSS would issue the “official” NOTAM. They can also submit a NOTAM if they believe it can affect pilots’ flight paths (e.g. model rocket launches, kite flying etc) to a country’s Aviation Authority who will then review it and officially issue a NOTAM, which will affect flights in that Aviation Authority’s airspace.

When is a NOTAM issued?

NOTAMs are created and promulgated at any time when the responsible authority deems them necessary and appropriate and have an expiry time of 3 months… In the US, the FAA Federal NOTAM System (FNS) publishes worldwide NOTAM data. Authorized administrators (usually Air Traffic Control) can publish their NOTAMs via the FAA NOTAM Manager, a web-based user interface application that enables publishers to manage their NOTAMs, which can be accessed by NOTAM Manager users (following an approval process).

What does a NOTAM look like and how do you decode one?

Example of a NOTAM for temporary restricted airspace

The Series is one letter A-Z, the number is a four digit number that starts from 0001 and increases consecutively for each series. Each one of these resets at the beginning of the year, meaning that on the 1st of January each series will have a 0001 NOTAM.

The the right is an example NOTAM that was in effect from July 1st-17th, showing a flight restriction around London during the Wimbledon tennis Championship. (Below is what it decodes to.)

Where can I find NOTAM data?

Finding a single source for all NOTAM data globally can be complicated. There are barriers to entry for certain providers, and NOTAMs are often published in inconsistent data formats. Cirium Sky provides a single source of spatially correct global NOTAM data.

Find out more about how you can access NOTAM data.




Series and Number


J0174 issued in 2017

Nature of the NOTAM





London FIR





Temporary restricted area






IFR and VFR traffic affected



NOTAM selected for PIB entry



NOTAM concerning flight operations



Aerodrome and Warning restriction affects both aerodrome and
en-route operations.

From Flight Level



Up to Flight Level



Centre Coordinates


51°29′ N 000° 13′ W

Radius of area affected


1 Nautical Mile

Location Indicator


London Heathrow

Valid from      


08:00 UTC 1 July 2017

Valid to


22:00 UTC 17 July 2017

Time schedule


Daily between 08:00 and 22:00 UTC

NOTAM description


Textual description of NOTAM.

Lower limit



Upper limit


Up to 1500 feet Above Mean Sea Level

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