UPDATE (7 Sept): Installation of the second new Instrument Landing System (ILS) began on Sunday 6 September. This is being installed at the Western end of the Southern Runway.
20 Aug,2015: The first of four new Instrument Landing Systems (ILS) has gone live at Heathrow, making it easier for us to land aircraft in adverse weather. Heathrow has four ILS in place, one for each runway in each direction of operation.
The ILS for runway 27 Right (27R) was replaced last week in an operation lasting just over five days and coordinated by Airside, NATS engineering teams, Air Traffic Control, and contractors Morgan Sindall.
The new ILS is based on new navigation technology and known as an “enhanced ILS” or eILS for short. The eILS provides Heathrow the capability to increase the number of aircraft that can land in low visibility giving improved resilience and punctuality.
Airports with CAT III runways can land aircraft in any weather and with zero visibility. At the moment our new eILS on runway 27R is at CAT I status, which means we can land aircraft when visibility and cloud cover is above 200ft but not below. Moving to CAT III takes a period of approximately 3 weeks of operation.
Mark Burgess, Head of Air Traffic Management & Flight Performance, said: “The three remaining ILS will be replaced over the coming 12 months. Replacing them is not an easy task however; as you cannot maintain the required scheduled landing rate at Heathrow whilst the ILS is being replaced.”
“Therefore the decision on when to do the work depends on many factors including the weather, the availability of the highly specialised contractors to carry out the work, and on minimising the impact on local communities.”
Five things about the ILS:
The new ILS is the only one of its kind in the UK;
There is only one other such system in Europe too, at Zurich Airport;
The system is designed and manufactured by Indra;
The new ILS is visibly wider than that it replaces;
Some 32 aerials have been installed as part of replacing the ILS on 27R.
In order to test the new ILS system, a flight check needs to be carried out. This is a CAA requirement following the introduction of a new system.
The checks are carried out by a small/light aircraft that does a number of loops testing the new system. This has to be carried out during the night when there are no other aircraft landing or taking off at Heathrow.
Geek spot – why does Heathrow actually have four runways?
To the naked eye Heathrow has two runways – the northern runway and the southern runway. Technically speaking though, we have four, known as 27 left and 27 right, and 09 left and 09 right.
The runways are named according to global aviation convention and depending on the direction of travel for departing and arriving aircraft. Aircraft need to land and take off into a prevailing wind (this is where the direction of travel point comes in). Our two runways run directly east to west.
The eastern edges of the runways point towards the 90 degree mark of a compass, the western edges directly to the 270 degree mark (with north at zero degrees, and south at 180 degrees).
If you are the pilot of an aircraft and you’re coming into land at Heathrow from the west (imagine you’re on final approach coming over Windsor) then you’re aircraft is pointing towards the east, 90 degrees on the compass in your cockpit. The two runways facing you at Heathrow are now 09 right or 09 left. That’s because, in the naming convention, the final zero is knocked off the compass heading you are facing, so 90 degrees becomes 09.
As a simple rule:
Northern runway – heading to the west is 27R, heading to the east is 09L.
Southern runway – heading to the west is 27L, heading to the east is 09R.
The left or right aspect is simply the runway to the pilot’s left or right. So, an aircraft coming into land on our northern runway, from the west and facing into the east, would be told to land on 09L – the runway faces 90 degrees on the compass, and is on the pilot’s left hand side.
An aircraft taking off to the east, but on the southern runway, would be operating of 09R – facing 90 degrees on the compass, on the pilot’s right hand side.
When aircraft are landing or taking off to the west (which happens approximately 70 per cent of the time here at Heathrow due to the prevailing westerly winds) then the heading becomes 27 left or right.
The pilots are facing 270 degrees on the compass and left or right depending on the direction of travel.
For more information please see our Q & A here.