What are the rules about altitudes?
The altitudes of aircraft over your suburb can vary according to:
- the airport the flight is coming from or going to
- whether the aircraft is coming in to land, taking off or in level flight
- the specific requirements of the flight path
- the need for air traffic control to maintain vertical separation between aircraft
There are no regulations setting out minimum altitudes for aircraft in the course of taking off or landing at an airport.
Landing aircraft will begin their final approach many kilometres from the airport at an altitude of around 3000 feet. They will descend on a glide slope of three degrees.
Variation in departure altitudes
You may observe differences in the altitudes of departing aircraft. Aircraft have different climbing abilities depending on factors such as the type of aircraft and its weight, how heavily laden it is, and even the meteorological conditions at the time.
Large jets such as A380s will climb more slowly than smaller, lighter aircraft because they are so much heavier. A380s are frequently used for long-haul non-stop flights and in these circumstances will be fully laden with fuel. This adds to the weight and further compromises climb performance. When two aircraft of the same type are observed to have different climb rates this is usually because one is heading for a closer destination than the other, and is therefore carrying less fuel weight.
Atmospheric conditions can affect climb rates. For example, when it is hot and humid the air is less dense. This affects the “lift” of an aircraft and it will take longer to climb in these conditions.
Minimum altitude for level flight
Aircraft in level flight must not fly over cities, towns or populous areas at a height lower than 1,000 feet, or over water or any other area lower than 500 feet, taken as height above the highest point in the terrain. However exceptions do apply, for example:
- in situations where the weather requires lower flying
- for helicopters flying within specified access lanes
- where the aircraft is engaged in “air work” for which the operator has a permit (such as media or traffic reporting helicopters)
- for police and search and rescue operations