ICAO type codes explained: how to read A20N, B38M, B77W and more

You open the flight tracker, tap the dot on approach and read: A20N. Next to it a B38M, behind it a B77W. For beginners this looks like gibberish, but for experienced spotters it is the fastest way to name an aircraft type. This guide shows you how ICAO type codes are built, the patterns the big manufacturers follow, what extras like L2J and M mean, and where the logic deliberately does not follow the model name.

ICAO type codes: the short answer

An ICAO type code, officially the Aircraft Type Designator, is an identifier of two to four letters and digits for an aircraft type. The International Civil Aviation Organization (ICAO) publishes the list in Document 8643. The code appears in the flight plan, on air traffic control screens and on most flight trackers. Most codes can be read like a kit: manufacturer letter, model number, variant. A359 is the Airbus A350-900, B789 the Boeing 787-9.

What matters is the purpose: ICAO distinguishes types by whether they behave differently for air traffic control – that is, by weight, speed, climb performance and engines. Whether an aircraft flies passengers or cargo is of no interest there. That is why an ICAO code is sometimes coarser, sometimes finer than the model name you know from the manufacturer.

ICAO or IATA: two systems for aircraft types

Besides the ICAO code, almost every airliner has a three-character IATA type code. It comes from the airlines’ Standard Schedules Information Manual and is used in schedules, booking systems and on departure boards. IATA distinguishes by commercial characteristics such as role, size or equipment – which is why freighters often have codes of their own there.

Type	ICAO code	IATA code	What the comparison shows
Airbus A320neo	A20N	32N	same logic, different notation
Boeing 737 MAX 8	B38M	7M8	ICAO uses the model number 737-8, IATA uses MAX
Boeing 777-300ER	B77W	77W	the W appears in both systems
Boeing 747-8F	B748	74N	ICAO does not separate cargo and passenger, IATA does
Airbus A320 with sharklets	A320	32A	ICAO has no sharklet code, IATA does

What role IATA codes play for airports and airlines and how to tell FRA from EDDF is covered in the basics article IATA and ICAO codes explained. This one deals exclusively with ICAO type designators, because those are exactly what you read on the live map.

The kit: manufacturer, model, variant

For the large airliners the code mostly follows a simple principle. The first letter stands for the manufacturer, followed by the digits of the model, and the last position names the variant.

• Airbus: A332 is the A330-200, A333 the A330-300, A359 the A350-900, A388 the A380-800. The last digit matches the variant number after the hyphen.
• Boeing: B744 is the 747-400, B752 the 757-200, B763 the 767-300, B788 the 787-8, B789 the 787-9. After the B come the first two digits of the model number, then the variant: 747-400 becomes B744.
• Embraer: E190 and E195 stand for the first E-Jet generation, E290 and E295 for the E2 variants. The 2 in second position marks the new generation.

With smaller manufacturers the code is more of an abbreviation of the name. AT72 is the ATR 72 of the older series (the ATR 72-600 has its own code, AT76), DH8D the De Havilland Canada Dash 8-400, CRJ9 the Bombardier CRJ900, C172 the Cessna 172. The D in DH8D stands for the fourth version of the Dash 8 series – the smaller siblings run as DH8A, DH8B and DH8C.

The letters at the end: N, M, W, K and X

It gets interesting when the end is not a digit. Then a generation or a special version is usually behind it.

Code	Aircraft	What the letter means
A19N, A20N, A21N	Airbus A319neo, A320neo, A321neo	N for neo, the generation with new engines
B37M, B38M, B39M	Boeing 737 MAX 7, MAX 8, MAX 9	M for MAX, the digit before it from the model number 737-7, -8, -9
B3XM	Boeing 737 MAX 10	X replaces the two-digit 10
B77W	Boeing 777-300ER	its own designator for the heavier, longer-range -300ER
B77L	Boeing 777-200LR and 777F	L for the long-range base, which the freighter also uses
A35K	Airbus A350-1000	K instead of the four-digit 1000
B78X	Boeing 787-10	X for the two-digit 10

The pattern behind it is easy to see through: four characters are not enough for every combination of manufacturer, model and variant. As soon as a variant becomes two-digit or a new generation is added, ICAO falls back on a letter.

Reading A20N: Airbus A320neo

A20N is a good example of the shortage of space. “A320neo” would need seven characters, so the 3 drops out: A for Airbus, 20 for the A320 model, N for neo. Likewise there are A19N and A21N. There is no A18N, because Airbus did not build an A318neo. The family’s classic models keep their full numbers A318, A319, A320 and A321. How to tell ceo from neo at the fence even without a tracker is shown in the guide Telling the A320neo from the ceo. The type itself is introduced in the profile of the Airbus A320neo; according to the type list, A21N by the way also covers the LR and XLR versions of the A321neo.

Reading B38M: Boeing 737 MAX 8

With B38M it is worth a look at the official model designation. Boeing internally calls the MAX 8 the 737-8, and that is exactly where the code comes from: B for Boeing, 38 from 737-8, M for MAX. The MAX 7 thus becomes B37M, the MAX 9 B39M. For the MAX 10 a digit is not enough, hence B3XM. You will find more on the type at the Boeing 737 MAX 8 and the Boeing 737 MAX 10.

Reading B77W: Boeing 777-300ER

With the 777 the scheme breaks down most clearly. B772 is the 777-200, B773 the 777-300 – logical so far. The 777-300ER, however, got its own code because it is much heavier and flies farther. You also find the W in the IATA code 77W for the same variant. The 777-200LR also has its own designator, B77L, which the freighter 777F shares with it. You can read the profile of the long-haul workhorse under Boeing 777-300ER; the differences from the 787 are explained in Telling the Boeing 777 and 787 apart.

The hidden extras: L2J and the wake turbulence category

In Document 8643, next to each code there is a short description of three characters. Many trackers and receiver programs like tar1090 show it or let you filter by it.

• First letter – construction type: L for landplane, H for helicopter. There are also separate letters for seaplanes and amphibians, gyrocopters and tiltrotors.
• Digit – number of engines: 1, 2, 3 or 4 for most types.
• Last letter – type of propulsion: J for jet engine, T for turboprop or turboshaft, P for piston engine.

Added to that is the wake turbulence category (WTC). It is based on the maximum certificated takeoff mass and determines how much separation air traffic control leaves behind an aircraft.

Category	Meaning	Maximum certificated takeoff mass
L (Light)	light	7,000 kg or less
M (Medium)	medium	over 7,000 kg and under 136,000 kg
H (Heavy)	heavy	136,000 kg or more
J (Super)	super	explicitly classified as such – currently only the A380-800

This gives every code a small profile. The values come from Eurocontrol’s aircraft performance database:

Code	Aircraft	Description	WTC	Max. takeoff mass per Eurocontrol
C172	Cessna 172 Skyhawk	L1P	L	1,050 kg
EC35	Airbus Helicopters H135 (EC135)	H2T	L	2,950 kg
DH8D	Dash 8-400	L2T	M	around 29,000 kg
A20N	Airbus A320neo	L2J	M	79,000 kg
B38M	Boeing 737 MAX 8	L2J	M	82,600 kg
B77W	Boeing 777-300ER	L2J	H	351,500 kg
A388	Airbus A380-800	L4J	J	560,000 kg

On the radio, by the way, you hear the category too: heavy aircraft often report with the addition “Heavy” after the callsign, the A380 with “Super”. Why this matters for separation is explained in Wake turbulence and separation. In Europe, Eurocontrol additionally works with the finer RECAT-EU classification, which lists A20N and B38M as “Upper Medium”, for example – but that plays no role in reading type codes.

Codes that carry old names

Type codes are rarely renamed when the brand name changes. For spotters that is a small history lesson in the tracker.

• BCS1 and BCS3: Today’s Airbus A220 was developed as the Bombardier CSeries. The codes for the A220-100 and A220-300 still recall that today.
• EC35: The Airbus Helicopters H135 still runs under the abbreviation of its former name, Eurocopter EC135.
• DH8D: The Dash 8-400 was long marketed as the Bombardier Q400, while the code points to the original manufacturer De Havilland Canada. The type has since returned to that name – so the code was proven right. More on this in the profile of the Dash 8-400.

The most common pitfalls when reading

If you transfer type codes into your logbook, sooner or later you stumble over the same spots. You should know these five.

• B737 is not the whole 737 family. The code designates only the 737-700. The 737-800 is B738, the 737-900 B739, and the older Classic models run as B733, B734 and B735. Which generation you have in front of you is explained in Telling Boeing 737 Original, Classic, NG and MAX apart.
• A320 does not mean “just any A320”. A320 stands for the ceo generation, the neo is A20N. If you note both as A320, you lose the information about the generation.
• No separate code for sharklets. An A320 with sharklets remains A320 at ICAO. Only the IATA system has codes of its own for that, such as 32A.
• Freighters hide. A 747-8F is B748, a converted 737-800BCF stays B738. Whether cargo or passengers – only the registration or the airline reveals that. More in Recognizing freighter aircraft.
• The tracker can be wrong. Aircraft do not transmit their type via ADS-B. Trackers match it from a database via the transponder’s hex address. If an entry there is outdated, the wrong type appears on the map. Background: ICAO 24-bit address (hex code).

Decoding an unknown code: step by step

Sooner or later a code shows up on the map that you have never seen. With this routine you usually arrive at the type within seconds.

The authoritative source is ICAO’s searchable type list for Document 8643. For everyday use, though, the trackers’ info windows are enough, as they mostly show code and spelled-out type together. What that looks like on Flightradar24 is described in the Flightradar24 guide.

Using type codes in practice while spotting

At the fence, type codes are above all a tool for filtering and organizing.

• Filter with purpose: Many trackers and receiver programs filter by type code. In tar1090 the expression B73. captures the whole 737 family, the description L2J all twin-engine jet landplanes. How this works is covered in the guide Installing readsb and tar1090; for the ADS-B Exchange web interface, ADS-B Exchange explained helps.
• Document cleanly: If you keep the ICAO code in your logbook instead of a free-text type name, you can sort, count and compare later. Tips on this are in Documenting sightings: the logbook.
• Set collecting goals: Many spotters keep their type list by ICAO codes because that makes the boundaries unambiguous. You will find ideas for this in Collecting all aircraft types.
• Day planning: A B77W or A388 in the day’s flight schedule is, at many airports, the reason to be standing at the Munich Airport visitors’ hill (Besucherhügel) or the Hamburg “Affenfelsen” (Monkey Rock) viewing area earlier.

Still, you should not take the type code as a substitute for looking. If you want to recognize types even without a tracker, the best start is Identifying aircraft types for beginners and Telling Airbus from Boeing.

Conclusion

ICAO type codes look cryptic but follow a comprehensible logic. Mostly the manufacturer is at the front, the model in the middle and the variant at the back. Letters like N, M, W, K or X mark new generations and special cases. Document 8643 also supplies a short description like L2J and the wake turbulence category. Because ICAO distinguishes by flight performance and not by use, freighters and sharklet versions stay invisible in the code. For an unambiguous sighting, the registration therefore always belongs with it.