ANEF vs N70: two ways of mapping aircraft noise

Resonate Consultants · 10 October 2026 · 4 min read

An ANEF map tells you how much aircraft noise an area is exposed to on average. An N70 map tells you how many times a day a plane will be loud enough to interrupt a conversation. Councils plan with the first. If you're deciding where to live, the second is often more useful.

What N70 means

N70 is the number of aircraft noise events louder than 70 dB(A) on an average day, measured outdoors. An N70 map shows contours for, say, 10, 20, 50 or 100 such events a day.

The 70 dB(A) figure wasn't picked at random. Federal guidance explains that a 70 dB(A) event outside is generally heard as about 60 dB(A) inside a house with the windows open, which is enough to interrupt a normal conversation or drown out the TV. So an N70 of 20 means roughly 20 times a day when you'd pause mid-sentence.

There are two common variations:

• N60 counts events above 60 dB(A). It's used for night-time, because a 60 dB(A) event outside is likely to produce about 50 dB(A) inside, the level AS 2021 sets for bedrooms. It's also used around training airports, where light aircraft fly circuits at around this level many times a day.
• N65 sits between the two, reflecting that people differ in how sensitive they are to noise.

How they compare

Why a site outside ANEF 20 can still be noisy

The ANEF averages a whole year of flights into one number, and it gives quiet days the same weight as busy ones. Runways change direction with the wind, so a suburb can be under a stream of departures one day and hear almost nothing the next. A modest number of loud flights also adds up to less exposure than you might expect.

The result is that people outside the ANEF 20 contour can hear a lot of aircraft. The federal government's guidance on supplementary noise metrics notes that most aircraft noise complaints come from residents outside the 20 contour. In Sydney, about 90% of complaints at the time came from outside the 20 contour of the ANEI, the equivalent map based on actual flights. As that guidance puts it, aircraft noise doesn't stop at a line on a map.

N70 maps fill that gap. A suburb that sits just outside ANEF 20 can still have dozens of events above 70 dB(A) on a typical day.

A third number: how loud is the loudest plane?

There's a third measure that matters when you build. AS 2021, the Australian Standard for building near airports, uses the maximum noise level of a single flyover in dB(A) to work out how much noise a building needs to keep out. That number comes from the site's distance to each runway and the aircraft forecast to use it.

So for a house near an airport, three numbers do three jobs:

• the ANEF band decides whether the site is acceptable and whether council's aircraft noise rules apply
• the maximum flyover level decides how well the building has to keep noise out
• the N70 tells you how often you'll notice the planes

There's more on the first two in What is ANEF? and What is AS 2021?

How planners use N-above contours

The National Airports Safeguarding Framework, agreed by federal, state and territory governments, includes Guideline A on managing aircraft noise. It suggests that new residential areas shouldn't be zoned on greenfield land where long-range forecasts show any of:

• 20 or more daily events above 70 dB(A)
• 50 or more daily events above 65 dB(A)
• 100 or more daily events above 60 dB(A)

Where more than six events of 60 dB(A) or more are forecast between 11 pm and 6 am, it suggests noise insulation and limits on noise-sensitive development may be appropriate. It also recommends telling prospective buyers about aircraft noise where these thresholds are met. The guidance is clear that these aren't hard lines, only areas where noise should be considered.

In NSW

NSW doesn't use N-above contours to set planning rules. The state's Aviation Safeguarding Guidelines (May 2026) say the NSW Government has endorsed ANEF and ANEC contours for land use planning, not N contours. Council aircraft noise clauses, and the rules around Western Sydney International, are all triggered by ANEF or ANEC contours. An N70 map won't usually change whether you need an aircraft noise report, but it's well worth looking at before you buy.

Where to find N70 information

• Western Sydney International: the government's Aircraft Overflight Noise Tool shows forecast flight numbers and noise for any address. The environmental impact statement has N70 and N60 contours; it forecasts that by 2055 between 7,000 and 12,200 residents could experience five or more events above 70 dB(A) a day.
• Sydney and other major airports: airport master plans and the Airservices aircraft noise pages, including the Aircraft in Your Neighbourhood portal.
• Measured events: Airservices' WebTrak shows flight tracks near Sydney and Western Sydney, and the number of events above 70 dB(A) recorded at its noise monitors.