Travel guides9 min read
- ICAO — the International Civil Aviation Organization. A specialised agency of the United Nations. Its members are countries (193 of them).
- IATA — the International Air Transport Association. A trade association. Its members are airlines (around 350, carrying most of the world's traffic).
Everything else follows from that. ICAO talks to governments about safety; IATA is how airlines agree with each other about commerce.
ICAO: the safety rulebook
ICAO was created by the Chicago Convention of 7 December 1944, when 52 countries met to prepare for post-war civil aviation.
Its main output is SARPs — Standards and Recommended Practices. These are the technical and safety rules: what an aircraft must meet, how a pilot must be trained, what equipment an airport needs, how an accident must be investigated.
ICAO does not regulate a single airline directly. It writes the standard, and each member state then puts that standard into its own law and supervises its own carriers. In Vietnam that authority is the Civil Aviation Authority of Vietnam. Put simply: ICAO writes the model law, the country enforces it.
ICAO also defined the "freedoms of the air" — the rules that decide what an airline from country A may do in country B: merely overfly it, land for fuel, carry passengers from its own country, or carry passengers between two points inside country B. Every international route you book sits inside a bilateral agreement built on that framework.
Most ICAO news on this site is of exactly that kind — standards that bind airlines, such as the rules on power banks on board.
IATA: the commercial rulebook
IATA was founded in Havana in April 1945, as the place where airlines agree on how to do business together.
What IATA standardises turns up throughout your journey, whether or not you notice:
- Three-letter airport codes — HAN, SGN, BKK. These are the codes on your ticket and on your bag tag.
- Two-letter airline codes — VN, VJ, SQ, CX.
- Electronic ticket numbers — every airline has its own three-digit number at the front of the ticket number. Vietnam Airlines is 738, Vietjet is 978. The first three digits tell you which airline issued the ticket.
- Booking classes and fare basis codes — the letters that decide whether your ticket can be changed and how much baggage it carries. We take those apart in the article on ticket codes.
- Settlement between airlines — the BSP system, which lets one agency sell tickets on dozens of airlines while settling through a single channel. It is the plumbing that makes a multi-airline itinerary unremarkable.
- Interline baggage — the rules for moving your bag between two different airlines on one ticket.
IATA has no state authority. An airline that is not a member flies perfectly legally — plenty of low-cost carriers stay outside it deliberately. But the airport and airline codes IATA issues are used by essentially the whole industry, members or not.
Side by side
| ICAO | IATA | |
|---|---|---|
| What it is | A UN specialised agency | A trade association |
| Members | Countries (193) | Airlines (around 350) |
| Founded | 1944, Chicago Convention | 1945, Havana |
| Concerned with | Safety, engineering, accident investigation, environment | Tickets, fares, baggage, settlement between airlines |
| How it binds | Through each country's own law | By voluntary agreement between airlines |
| Airport codes | 4 letters — VVNB | 3 letters — HAN |
| Airline codes | 3 letters — HVN, VJC | 2 letters — VN, VJ |
| Where you meet it | Air traffic control, flight plans, radar | Tickets, boarding passes, bag tags |
One common mistake: "IATA standard" is not a safety certificate
People often assume an IATA airline is a safer airline. Not quite.
What decides whether an airline may fly at all is the licence issued by its national aviation authority, against ICAO standards. IATA does run its own operational safety audit, IOSA, and that is a real inspection — but it is a condition of IATA membership, not permission to take off.
The reverse holds too: a low-cost airline outside IATA still has to meet every safety standard its regulator applies under ICAO.
Common questions
Which is "bigger", ICAO or IATA?
They are not the same kind of thing, so they do not compare directly. ICAO has international authority over safety through its member states; IATA has commercial influence through its member airlines.
Why is Noi Bai both HAN and VVNB?
HAN is the three-letter IATA code used in selling; VVNB is the four-letter ICAO code used in operations. They serve different purposes, so both exist. See the article on airport codes.
What is Vietnam Airlines' airline code?
VN in IATA, HVN in ICAO, and 738 is the number at the front of its ticket numbers. Vietjet is VJ, VJC and 978.
Are non-IATA airlines safe?
Safety is determined by the licence from a country's aviation authority, applying ICAO standards — not by IATA membership. Several of the world's largest low-cost carriers are not IATA members.
Are the airline alliances part of IATA?
No. SkyTeam, Star Alliance and Oneworld are commercial alliances between groups of airlines, independent of IATA. See the article on SkyTeam.
Read on
Airport and city codes · The codes on your ticket · A history of commercial aviation · Industry terms: ASK, RPK, PLF, Yield
Sources and dates
Organisational detail follows ICAO's and IATA's own published material. The number of ICAO member states and IATA member airlines changes over time; the figures here were recorded at publication, 15 September 2026.
