Decoding NOTAM Q-codes and abbreviations

The plain-language line of a NOTAM tells you what is going on, but the coded qualifier line, the Q-line, is what lets a briefing system sort, filter, and find the one that affects you. Learning to read it turns a wall of capitals into a structured notice. This guide goes a level deeper than our overview of understanding NOTAMs.

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.

Where the Q-line sits

A NOTAM in the ICAO format is built from a number and type, a qualifier (Q) line, and a set of lettered fields. Take this runway closure:

A1234/26 NOTAMNQ) EGTT/QMRLC/IV/NBO/A/000/999/5129N00028W005A) EGLL B) 2604100600 C) 2604101800E) RWY 09L/27R CLOSED DUE WIP

The E) line is the human-readable text. The Q) line is the machine-readable summary, and it is the part most pilots skim past. It is worth slowing down on, because every field has a job. The format and the code tables come from ICAO Annex 15 (Aeronautical Information Services) and the ICAO AIS manuals (Doc 8126), with the full Q-code list published by the FAA in Order JO 7930.2, Appendix B.

The five-letter Q-code

The heart of the Q-line is the five-letter Q-code, here QMRLC. It always starts with Q, and the remaining four letters split into two pairs:

• The subject is the second and third letters, here MR, meaning runway. The subject says what the NOTAM is about: a runway, a taxiway, a navigation aid, an airspace, an obstacle, a procedure, and so on.
• The condition or status is the fourth and fifth letters, here LC, meaning closed. The condition says what has happened to that subject.

So QMRLC reads as "runway closed". A few more examples show the pattern:

• QFALC is aerodrome (FA) closed (LC).
• A navigation aid unserviceable uses the condition letters AS, for unserviceable.
• A subject or condition with no exact code uses XX, which signals that the meaning is spelled out in the plain-language E) line instead.

You do not need to memorise the tables. You need to know the structure, so that when you meet an unfamiliar code you can split it into subject and condition and look each part up in the official list.

The qualifiers: traffic, purpose, scope

After the Q-code come three qualifiers that a briefing system uses to decide who needs the NOTAM:

• Traffic (IV in the example) says which traffic is affected: I for IFR, V for VFR, or IV for both.
• Purpose (NBO) says why the NOTAM matters and where it goes. The letters are drawn from N (for the immediate attention of aircrew), B (of operational significance, so it belongs in the pre-flight information bulletin), O (flight operations), and M (miscellaneous). A combination like NBO means the NOTAM is significant enough for aircrew and for the briefing package.
• Scope (A) says how widely it applies: A for aerodrome, E for en-route, W for a navigation warning, or combinations such as AE.

These three qualifiers are exactly what lets an app or a briefing service show you only the IFR aerodrome NOTAMs for your destination, instead of every notice in the region.

The height and location fields

The last fields on the Q-line pin the NOTAM in space:

• Lower and upper limits (000/999) are flight levels. 000/999 means from the surface to unlimited, the usual range for an aerodrome NOTAM. An airspace NOTAM will carry a real band, such as 100/245.
• Coordinate and radius (5129N00028W005) give the centre point, here 51 degrees 29 minutes north, 000 degrees 28 minutes west, with a radius of 5 nautical miles.

For airspace and navigation NOTAMs the same height information is repeated in plain form in the F) and G) fields, and the D) field carries a schedule when the activity is intermittent, for example active only during certain hours.

The contractions

The E) line itself is written in upper case using standard contractions, which is why it can look impenetrable at first. RWY 09L/27R CLOSED DUE WIP is "runway zero nine left, two seven right closed due to work in progress". The contractions are standardised so they mean the same thing everywhere, drawn from the ICAO abbreviations (Doc 8400) and, in the United States, the FAA contractions order (JO 7340.2). Common ones include U/S (unserviceable), WIP (work in progress), AD (aerodrome), TWY (taxiway), ACFT (aircraft), PSN (position), and O/R (on request).

A second example: an en-route navigation aid

The runway closure above is an aerodrome NOTAM. To see how the same structure handles something different, take a navigation-aid outage with an en-route scope:

Q) EGTT/QNVAS/IV/BO/E/000/250/5215N00112W025A) EGTT B) 2604100800 C) 2604101600E) VOR 'XYZ' 113.50 MHZ U/S

Reading the Q-line field by field shows how each part has shifted to match the new subject:

• EGTT is again the London flight information region.
• QNVAS is the Q-code. The subject letters NV mean a VOR, and the condition letters AS mean unserviceable. So QNVAS reads as "VOR unserviceable", where the earlier QMRLC read as "runway closed". (Mind the neighbouring codes: in the ICAO list NM is a VOR/DME and ND a DME, so the subject letters are worth reading precisely.) The structure is identical; only the subject and condition have changed.
• IV is the traffic: both IFR and VFR are affected, because a VOR outage matters to anyone navigating by it.
• BO is the purpose: of operational significance, so it belongs in the briefing package.
• E is the scope: en-route, not aerodrome, because a VOR serves the airway structure rather than a single field.
• 000/250 are the lower and upper limits, here from the surface up to flight level 250, the band in which aircraft would use this aid.
• 5215N00112W025 is the centre and a 25 nautical mile radius, a much larger area than the 5-mile aerodrome example, because an en-route aid is relevant over a wide region.

The E) line then says it plainly: the VOR identified XYZ on 113.50 MHz is unserviceable. Put the two examples side by side and the value of the Q-line is obvious. Without reading a word of plain text, a briefing system knows that the first NOTAM is an aerodrome runway closure affecting all traffic at the surface, and the second is an en-route navigation-aid outage affecting all traffic up to flight level 250 across a 25-mile area. That is exactly the information needed to decide which NOTAMs reach which flights.

Common subject and condition pairs

You will meet the same Q-code building blocks again and again, so it helps to recognise the frequent ones, while remembering that the authoritative list is in FAA Order JO 7930.2, Appendix B and the ICAO tables, and that anything you are unsure of should be looked up rather than guessed.

Among the subject pairs (the second and third letters), you will often see codes for the movement area and its lighting, runways, taxiways, aprons, and the approach and runway lights, as well as the navigation aids, the ILS, VOR, DME and NDB, and airspace subjects for restricted, danger, and temporary reserved areas.

Among the condition pairs (the fourth and fifth letters), a handful do most of the work:

• LC means closed.
• AS means unserviceable.
• CA and CD mean activated and deactivated.
• TT marks a trigger NOTAM, which flags a coming permanent change that will be published in the AIP.
• XX means there is no specific code, so the meaning is spelled out in plain language in the E) line.

Put a subject and a condition together and you can read most codes at sight: a runway subject with LC is a runway closure, a navigation-aid subject with AS is an aid out of service, and an airspace subject with CA is an area being activated. The structure is what lets you decode an unfamiliar code, and the official tables are what confirm it.

Common pitfalls

• Skipping the Q-line. The plain text tells you the what; the Q-line tells a system who, where, and how high, which is how the right NOTAM reaches you.
• Guessing a code. A Q-code you do not know should be looked up, not assumed. Subject and condition pairs are precise.
• Misreading the limits as altitudes. The 000/999 figures are flight levels, not feet.
• Treating dates as local. The B) and C) validity times are UTC, like everything else in a NOTAM.
• Ignoring EST. An end time followed by EST is only estimated; the NOTAM will be replaced or cancelled later, so it may outlast its stated end.

In Pilot EFB

Pilot EFB includes a searchable, offline reference of common ICAO Q-codes and abbreviations, so when a NOTAM throws up a code or contraction you do not recognise you can look it up on the spot. It is a lookup tool: it shows you what a code means, and it never interprets the NOTAM for you or tells you what to do about it. The full raw NOTAM is always kept, with keywords highlighted to help you scan. NOTAMs you have already pulled stay readable with no signal, while getting the latest issued NOTAMs needs a connection. Pilot EFB is offline-first and is not a certified Electronic Flight Bag, so confirm against the official AIS source before you fly.