29 SEPTEMBER 2014

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Article from BTNews 29 SEPTEMBER 2014

COMMENT: A380s at Heathrow

The American magazine Aviation Week, normally highlighting more military aviation than commercial is now questioning the Airbus A380 and potential problems at Heathrow.  BTN acknowledges the edited use of a feature dated 1 September

Some 15 A380s operate into Heathrow every day.  Emirates flies A380s on all five of its daily London – Dubai rotations, while Singapore Airlines uses the type on three of its four flights.  And the number looks set to rise, with British Airways taking delivery of more A380s in the coming months, to be joined by Qatar Airways and Etihad in October and December, respectively.

Operations at Heathrow were considered a key market for the Airbus A380.  Its increasing use may be affecting airport efficiency.

But ever-increasing A380 operations at Heathrow could also potentially have a negative impact on what is the world’s busiest two-runway international airport, suggest officials from NATS.

Senior NATS air traffic controllers say the biggest impact comes from the spacing requirement for the aircraft, which is in the “super” wake vortex category.  As an A380 departs, it requires up to three minutes of spacing between it and the next aircraft if – as it often is at Heathrow – it is a smaller narrowbody type, such as an Airbus A320 or Boeing 737.

Because the airport routinely operates at around 99% of its runway capacity, the three-minute hold time before the aircraft behind the A380 can depart can have a significant impact on the number of aircraft that can use the runway per hour.

Greater distances between traffic are also required on approach. According to International Civil Aviation Organization (ICAO) guidelines, minimum separation for a “heavy” category aircraft such as a Boeing 747 behind an A380 is 6nm, two more than behind another 747.  Medium-size aircraft up to the Boeing 757 have to keep a 7nm separation and smaller aircraft eight.

Heathrow aims for around 42-44 movements or departures per hour per runway, but if that figure dips below 36, operations managers may not be able to fit the day’s schedule into one day, affecting the airport’s hub operations.

Significant impacts are also felt with the A380’s relatively high runway occupancy time (ROT) – for landing run and taxi-off – as well as line-up (for take-off) times (LUT).

According to Jon Proudlove, NATS General Manager at Heathrow, Boeing 747s can take around 45 seconds to taxi onto the runway and line up ready for departure, but A380s are taking around 65 seconds.  A Heathrow report on A380 operations states that on one occasion, it took an A380 as long as 111 seconds to line up on runway 27L.

“Heathrow operates on a knife edge,” says Proudlove. “The impact of these aircraft nibbles away at runway capacity. “By 2030 we expect to handle up to 60 A380s a day, but there is no plan for that, we can’t plan for that,” he says.

With 104 weekly A380 flights, Heathrow handles the second-most A380 flights worldwide. Because Emirates’ fleet of 50 A380s is based in Dubai, that airport is the busiest for the type, with 297 weekly departures. Dubai is exceptional, as a lot of the latest airport infrastructure investments have been planned around A380 operations – Emirates even operates into an A380-dedicated terminal. The airport also underwent runway and taxiway upgrades this year that allowed smoother operations, but they were not directly linked to A380 services.

What Heathrow is facing today could well look like a glimpse into some of the future issues faced at other airports seeing increasing numbers of A380s.  Singapore has 104 and Paris Charles de Gaulle 94 weekly flights; Frankfurt has 76; Seoul Incheon 75 and Los Angeles International 70. Sydney has 47 weekly A380 flights. The level of current issues is different at these locations, however.  Charles de Gaulle generally has ample runway capacity and continues to add terminal space.  Frankfurt opened a fourth runway and therefore has more capacity than it currently needs; its limits are dictated by passenger terminal constraints.  And A380 operations have already been taken into account in Seoul Incheon’s planning process.

There are several approaches to mitigating the A380’s impact. In theory, with more A380s operating into Heathrow, the aircraft could be grouped on departure, allowing an A380 to leave after another A380 within a minute or so, but opportunities to do this are few and far between.

NATS and the airport authorities have been working with the airlines on reducing the ROT and LUT times and NATS says performance is significantly enhanced by the use of Airbus’s Brake To Vacate (BTV) system.

According to Airbus, nine of the current 11 A380 operators have picked BTV comparable with smaller narrowbody types.  Airbus Test Pilot Jean-Michel Roy says that airlines that have chosen BTV routinely use it, but runway occupancy times for Heathrow landings suggest that pilots may not consistently apply it.  And only three of the five A380 operators flying to Heathrow have BTV installed.

The system functions when the aircraft is in autoland mode. BTV tells the pilots on the primary flight display where the earliest possible position on the runway will be during dry or wet conditions, and with a preselected deceleration rate in place.  The crew can then select an exit after that position and BTV will automatically decelerate the aircraft in the most efficient way to a taxi speed, at which point pilots will take full manual control again.  According to Roy, airlines can therefore reduce runway occupancy time from around 90 to 60 seconds.

Once pilots prepare BTV during the approach, the computer will tell them the expected ROT. The crew can therefore tell air traffic control in advance how much time it expects will be needed until the aircraft has left the runway again. Airbus argues this will make it easier for ATC to plan spacing in the arrival pattern.

Airbus also has been working with ICAO to re-address the minimum separation criteria put in place for the A380. The latest round of flight tests – involving several smaller aircraft types flying behind A380s at various angles, speeds and other changing conditions – took place in 2010, and working groups are still assessing the data. Airbus has been trying to persuade authorities to move the A380 back into the “heavy” category from its own “super-heavy” definition. The outcome of those talks and the timing of any conclusions is still unclear.

A380 Product Marketing Director Thomas Burger claims that if air traffic control manages to group A380 arrivals, even under the current ICAO regulations A380s increase runway capacity because the restrictions do not apply when one A380 follows another and because of their high passenger capacity.

Space and taxiway limitations can make ground operations more difficult for the aircraft. At Heathrow a major issue is that significant sections of the taxiway system linking Terminal 3 to Terminal 1 on the north side of the airport is not ICAO Code F-compliant, making it unavailable for use by the A380 because of its 79.75 metre (261ft) wingspan.

As a result, A380s landing on the northern runways – 09L or 27R – can only vacate the runway at two intersections, forcing ground controllers to take the aircraft on lengthy routes around the airfield to reach their stands.  Use of the northern taxiways will only be possible once Terminal 1 and its associated piers have been demolished as part of the Terminal 2 development.

For operators using Terminal 4 on the south side of the airport, such as Malaysian Airlines, A380 operations are complicated by the southern runway.  Qatar Airways and Etihad are going to have problems.

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