Approach categories — CAT I, II and III — are runway certification standards that set the lowest visibility in which an aircraft may legally attempt a landing. CAT I requires a runway visual range of at least 550 metres and a decision height no lower than 60 metres. CAT II tightens that to 300 metres. CAT III covers anything below.
No civil aviation authority publishes those per-runway certifications in a passenger-readable form, so the airport-by-airport reference travelers want does not exist as a single document. It can only be pulled together from national AIPs, one state at a time.
Every fog season, Asia-Pacific hubs do what they always do: slow arrivals, cancel departures, and occasionally send a widebody to a city it was never scheduled to visit. Travelers read “weather below minima” in an airline app and move on.
That phrase hides a specific, checkable fact about the runway your flight was cleared to use — whether it is certified to let an aircraft land at all in the visibility of the day.
The certification is called an approach category. It runs from CAT I to CAT III, and the gap between them is measured in hundreds of metres of visibility. A runway certified to CAT III can support landings in conditions that would force a CAT I runway to divert. The categories are not marketing labels — they are hard operational ceilings, and they tell an airline what its aircraft and crew may legally attempt at that specific strip of pavement.
Here is the snag. The data exists — states are required to publish it — but almost nobody publishes it where a passenger can read it. There is no consolidated APAC reference linking individual runways to their certified categories.
What follows is the framework behind that missing reference, and an honest account of what could and could not be verified while building it.
CAT I, II and III approaches explained
A runway doesn’t get a category because an airport decided it should have one. The category falls out of physical characteristics, lighting and navigation aids. Those inputs are then translated into two numbers: the minimum runway visual range and the decision height at which a pilot must either see the runway or break off the approach.
For a CAT I precision approach, the usual minimums are a runway visual range of at least 550 metres and a decision height no lower than 60 metres. That is the everyday instrument landing most travelers will ever encounter without knowing it.
CAT II steps down sharply. It calls for a runway visual range of at least 300 metres, paired with a decision height below 60 metres but not below 30. CAT III covers everything under that floor — a runway visual range below 300 metres, with a decision height below 30 metres or none at all.
Below the precision approaches sit non-precision runways, usable where visibility is generally not less than 1,000 metres and where pilots lean on a mix of visual and non-visual aids rather than a full instrument guidance system.
Read those thresholds together and the practical picture appears: which category your airport holds is the difference between a delay and a diversion.
What runway visual range and decision height mean for your flight
Runway visual range is a measurement, not an estimate. It records how far a pilot can actually see down the runway surface in the prevailing conditions, typically reported by instruments beside the strip. Decision height is the altitude on the approach where the pilot must have the runway environment in sight — or go around.
Those two figures interact with the runway’s category floor. If the reported visibility drops below what the runway is certified for, the approach cannot be attempted, no matter how capable the aircraft or how experienced the crew. The flight holds, diverts, or never departs.
This is where the phrase “weather below minima” lands in practice: the fog is thicker than the runway’s certification allows an approach to go. Nothing is broken, no one is at fault — the runway simply cannot support the landing it is being asked to accept.
For a traveler, the useful shift is to stop reading the weather and start reading the runway. A red-eye arrival into a fog-prone hub, or a tight connection through a single-runway airport, carries different risk depending on what that runway is certified to handle. The category is the variable the airline cannot change and you cannot see.
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Why APAC airport certification data is hard to find
The publication duty is not a secret: under ICAO standards, a state’s national AIP must include aerodrome certification status, and AD 1.5 is the specific section designated for that disclosure. In theory, anyone can open the AIP and read which runways hold which categories.
In practice, that section frequently goes unpublished. According to ICAO, 356 of 386 Asia-Pacific aerodromes used for international operations had been certified as of 2 March 2026 — a completion figure of 92.23%. Even so, the same reporting listed states that had never posted certification data in AD 1.5 at all, Brunei Darussalam among them, alongside Afghanistan, Kiribati, Tuvalu, Nauru, the Marshall Islands, Palau and Micronesia.
That is the gap in one sentence: certification on the state’s side, silence on the passenger’s. The certification exists; the disclosure does not.
That patchwork is why travelers have nowhere single to look. The definitions are public and identical everywhere. It is the per-runway attachment — this category, at this runway identifier, at this airport — that scatters across national documents following no shared format.
The table below shows exactly how far a passenger can get from primary sources, and where the trail goes cold. There is a fuller account of why the region’s regulators leave the disclosure unfinished if you want the compliance story in detail.
| Airport | Runway ident | Certified precision-approach category | Published RVR/decision-height minima | Source AIP section |
|---|---|---|---|---|
| Singapore Changi | 02L/20R | CAT I ILS generally available | Not stated in the retrieved excerpt | Singapore AIP ENR 1.5; procedures referenced in WSSS AD 2.24 |
| Singapore Changi | 02C/20C | CAT I ILS generally available | Not stated in the retrieved excerpt | Singapore AIP ENR 1.5; procedures referenced in WSSS AD 2.24 |
| Singapore Changi | 02R | CAT I ILS generally available | Not stated in the retrieved excerpt | Singapore AIP ENR 1.5; procedures referenced in WSSS AD 2.24 |
| Source: Civil Aviation Authority of Singapore (CAAS) | ||||
The Singapore entries come from the Civil Aviation Authority of Singapore’s AIP, which states that CAT I ILS is generally available on the Changi runways it lists. It also routes CAT II specifics to WSSS AD 2-22. The retrieved excerpt, however, does not state the runway-level CAT II assignment or its minima.
How a runway’s category reaches paper — or doesn’t
The duty to disclose doesn’t rest with the airport alone. Annex 14, Volume I, paragraph 2.13.1(a) puts it on the aerodrome authority, which has to send its certification details to the state’s aeronautical information service for publication.
Two further provisions carry that requirement into the AIP itself. PANS-Aerodromes (Doc 9981, Part I, paragraph 2.3.7) and PANS-AIM (Doc 10066, Appendix 2) together route the status into Part 3 — Aerodromes, with AD 1.5 as the standard section. The required entries are narrow: aerodrome name and location indicator, certification date, validity where it applies, and remarks.
So the framework is precise about where the information should live and what it should contain. What it cannot do is guarantee a state fills it in. The chain runs authority to service to published document, and a single unfilled link leaves the passenger with no readable record — even for a runway that passed its certification inspection years ago.
What this means for you
When fog pushes a runway below its certified minimums, the downstream effects follow a familiar pattern: delays, cancellations and diversions. Macau International Airport’s own passenger guidance draws that link explicitly, and notes that persistent fog is the condition most likely to send a flight to a nearby alternate airport rather than merely hold it.
What that does not create is an automatic right to rebooking or compensation. Whether you are owed anything turns on your itinerary, the operating carrier, the law that governs the ticket, and what caused the disruption. Weather is, in most regimes, a cause the carrier does not control — which is why a fog disruption often ends in a hotel queue rather than a claim form.
The stronger move is upstream. The approach category of the runway you’re scheduled onto is the one variable a passenger can check before booking.
It won’t appear in an airline app. It sits in the state’s AIP — Part 3, Aerodromes, AD 1.5 — which is free to read and almost never read by passengers.
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Key terms
- Approach category
- An approach category is the certification that sets the lowest visibility in which an aircraft may legally attempt a landing on a particular runway. It follows from the runway’s physical characteristics, lighting and navigation aids, and runs from CAT I at the most permissive end to CAT III at the least. Because the certification attaches to a strip of pavement rather than to an airport as a whole, one airport can hold different categories on different runways.
- Runway visual range
- Runway visual range is the distance a pilot can see down the runway surface in the prevailing conditions. It is normally measured by instruments beside the strip rather than judged by eye, and it sits alongside decision height as one of the two minima that govern an instrument approach. In practice it is the figure that turns a weather forecast into an operational decision about a specific runway.
- Decision height
- Decision height is the point on an instrument approach at which the pilot must have the runway environment in sight, or break off and go around. It is measured as a height above the runway rather than an altitude above sea level, and it tightens as the approach category increases. The two figures move together, which is why a lower visibility floor on a runway also means a later point of decision for the crew.
- Aeronautical Information Publication (AIP)
- The Aeronautical Information Publication is the document a state issues to set out its aviation rules, procedures and aerodrome data. Under ICAO standards its Part 3 — Aerodromes — carries the certification status of each aerodrome, with AD 1.5 as the section designated for that disclosure. Where that section is left blank, a traveler has no way to confirm a runway’s certified approach category before booking.
Questions? Answers.
What is a category 3 airport?
There is no official register that labels airports “category 3” — the label applies to a runway certified for CAT III approaches, meaning a runway visual range below 300 metres and a decision height below 30 metres or none at all. No authoritative, passenger-facing third-party list covering APAC runway approach categories was verified, so the certified detail lives in each state’s national AIP rather than in any consolidated public document.
Which airports have cat 3 ILS?
That question has no verified consolidated answer. No authoritative, passenger-facing third-party list covering APAC runway approach categories was verified in the research behind this piece, so checking a specific airport means opening its national AIP — Part 3, Aerodromes, section AD 1.5 — and reading the certification status published there, assuming the state has published it.
If low visibility disrupts my flight into an APAC hub, can I expect rebooking or compensation?
Low visibility can produce delays, cancellations and diversions, and persistent fog may push a flight toward a nearby alternate airport. None of those outcomes on its own creates a universal right to rebooking or compensation. What applies depends on your itinerary, the operating carrier, the governing law and what caused the disruption.
How many APAC aerodromes handling international operations are certified?
356 of 386 Asia-Pacific aerodromes used for international operations had been certified as of 2 March 2026 — a completion figure of 92.23%, according to ICAO. Even so, the same reporting listed states that had still not published certification status in their AIP AD 1.5 sections.
