Is the house under a flight path? What to check before you offer

You have viewed a house on a Saturday afternoon and heard nothing but a lawnmower. Then the neighbour mentions, casually, that the planes start at half past four. Being near an airport is not the same as being under its flight path, and being under one on Tuesday is not the same as Wednesday. The difference is worth understanding before you put a number in an email, because you cannot double glaze a garden.

Which runway, not which airport

Every airport has a set of arrival and departure routes, and the noise is concentrated along them, not spread evenly around the airfield. Arrivals are the steady ones: aircraft line up on the centreline from miles out and come down a fixed glide slope, so a house under an approach hears every landing. Departures climb and turn along published Noise Preferential Routes, so the noise fans out more but is louder at the start.

At Heathrow the direction depends on the wind. Aircraft take off and land into it, so on westerly days (about seven in ten) they land over London from the east, and on easterly days over Windsor. On top of that, Heathrow alternates its two runways during westerly operations, swapping the landing runway at 3pm each day and switching the pattern weekly, so a house in Richmond or Hounslow gets half a day of relief and then half a day of arrivals. The same address can be quiet at one viewing and loud at the next for ordinary reasons.

What do the noise maps actually show?

The Civil Aviation Authority publishes noise contours every year for Heathrow, Gatwick and Stansted, and most other large airports publish their own. The contours are drawn in LAeq, an average sound level over the 16 hour day, in steps of 51, 54, 57, 60, 63 and so on. The 57 dB LAeq contour was for decades the government's marker for the onset of significant community annoyance, and it still shapes a lot of policy. Since 2017 the threshold for adverse effects has been set lower, at 51 dB, so a house outside the 57 line is not necessarily quiet, just quieter.

Defra's strategic noise maps, produced under the Environmental Noise Regulations, cover aircraft, road and rail together and are searchable by postcode. For live evidence, most big airports run WebTrak or similar, which shows each aircraft's track and height over a map in near real time. Put the address in and watch.

Can I get help with the noise?

If the house sits inside the busier contours, the airport may pay for insulation. Heathrow, Gatwick, Manchester and others run noise insulation schemes with eligibility set by contour, typically covering acoustic glazing and ventilation for bedrooms and living rooms. Ask whether the owner has already claimed, because the scheme may not pay twice. Check the glazing: proper acoustic glass with a wide gap between panes makes a real difference, standard double glazing rather less.

Bear in mind that routes change. Under the airspace modernisation programme most UK airports are redesigning arrival and departure routes through public consultations, and a street that is quiet now can be under a new route in a few years, or the reverse. The consultation documents name the areas affected.

What should I ask?

Ask the agent which runway and routes the house is under, and whether the seller has had a noise insulation grant. Ask the neighbours what time the first arrival is and whether summer is worse. Ask your solicitor whether the local search mentions an airport consultation or safeguarding zone. Then do the thing that beats every map: go back at 6am on a weekday, stand in the garden and count.