Brake to Vacate
Encyclopedia
Brake to Vacate is a device planned by Airbus
for incorporation on its line of airliner
s, intended to reduce runway
overruns. A more tangible benefit is the increased ability to exit the runway at a specified turnoff point. The European Aviation Safety Agency
is expected to certify the system, initially for use on the Airbus A380
, in July or August 2009. The second Airbus product to incorporate BTV will be the Airbus A320 family
, which is much more widely used around the world than the A380. However, an A320 BTV system would be more modest, since its flight computer does not incorporate the extensive electronic architecture of the A380.
are required to achieve that distance.
, the BTV automatically disconnects at 40 to 50 knots groundspeed (depending on conditions).
The greatest potential advantage of the system is its ability to predict whether an aircraft will be able to stop safely on a specified runway. The pilot selects the runway and enters the reported surface conditions (wind direction, windspeed, wet or dry, cleared or slushy), and the computer uses stored runway information, computed aircraft weights and required approach speeds, and computed flare/touchdown characteristics to predict whether the stopping point will lie outside the runway's endpoint.
,
with the first test landing in that aircraft accomplished in March 2005. The first test landing of an A380 using the BTV system was performed in May 2008.
Airbus initially announced its plan to make the BTV system available by 2007, but the production bottlenecks that Airbus encountered in meeting the initial A380 delivery schedules apparently pushed back development of several such planned improvements. As of 2009 the company is seeking certification
initially on the A380, after which it will announce planned incorporation schedules for other aircraft in the Airbus airliner product line. In 2006 Airbus indicated that following its introduction on the A380, the BTV "[would] be followed by retrofits available on all of other Airbus aircraft families." However, as of 2009 the company is indicating only that it will work on incorporating the feature on new A320s, and no definite availability schedule has been announced.
In 2005 Airbus also announced its intention to incorporate BTV into the upcoming Airbus A350
. However, since then that project has suffered several redesign phases, and it is not clear whether the BTV will still be offered when the A350 does come to market.
Airbus
Airbus SAS is an aircraft manufacturing subsidiary of EADS, a European aerospace company. Based in Blagnac, France, surburb of Toulouse, and with significant activity across Europe, the company produces around half of the world's jet airliners....
for incorporation on its line of airliner
Airliner
An airliner is a large fixed-wing aircraft for transporting passengers and cargo. Such aircraft are operated by airlines. Although the definition of an airliner can vary from country to country, an airliner is typically defined as an aircraft intended for carrying multiple passengers in commercial...
s, intended to reduce runway
Runway
According to ICAO a runway is a "defined rectangular area on a land aerodrome prepared for the landing and take-off of aircraft." Runways may be a man-made surface or a natural surface .- Orientation and dimensions :Runways are named by a number between 01 and 36, which is generally one tenth...
overruns. A more tangible benefit is the increased ability to exit the runway at a specified turnoff point. The European Aviation Safety Agency
European Aviation Safety Agency
The European Aviation Safety Agency is an agency of the European Union with offices in Cologne, Germany, which has been given regulatory and executive tasks in the field of civilian aviation safety. It was created on 15 July 2002, and it reached full functionality in 2008, taking over functions...
is expected to certify the system, initially for use on the Airbus A380
Airbus A380
The Airbus A380 is a double-deck, wide-body, four-engine jet airliner manufactured by the European corporation Airbus, a subsidiary of EADS. It is the largest passenger airliner in the world. Due to its size, many airports had to modify and improve facilities to accommodate it...
, in July or August 2009. The second Airbus product to incorporate BTV will be the Airbus A320 family
Airbus A320 family
The Airbus A320 family is a family of short- to medium-range, narrow-body, commercial passenger jet airliners manufactured by Airbus Industrie.Airbus was originally a consortium of European aerospace companies, and is now fully owned by EADS. Airbus's name has been Airbus SAS since 2001...
, which is much more widely used around the world than the A380. However, an A320 BTV system would be more modest, since its flight computer does not incorporate the extensive electronic architecture of the A380.
Operation
The BTV is a subset of the airliner's auto-flight computer, and allows that computer to be programmed for a pre-selected stopping distance. It indicates (and to some extent directs) which combination of brakes and thrust reversersThrust reversal
Thrust reversal, also called reverse thrust, is the temporary diversion of an aircraft engine's exhaust or changing of propeller pitch so that the thrust produced is directed forward, rather than aft. This acts against the forward travel of the aircraft, providing deceleration...
are required to achieve that distance.
On approach
The BTV uses the airliner's existing warning systems to alert the crew if unsafe conditions exist. If the system computes that the runway is too short when wet, an amber message appears in the primary flight display. If it computes that the runway is too short even under dry surface conditions, RWY TOO SHORT (in red letters) is flashed on the primary flight display, accompanied by an aural signal.During rollout
When the aircraft landing gear is firmly on the runway surface, the BTV combines audio and visual prompts to the flight crew in order to achieve the calculated required deceleration to achieve the designated turnoff point. If BTV senses that the aircraft will overrun the runway end, it automatically applies maximum wheel braking, and it sends an aural message (to the flight crew) to apply maximum reverse thrust, along with a red message in the primary flight display. It continues to call out keep max reverse until the computer figures the desired turnoff point can be achieved at a safe turnoff speed. If the taxiway departs the runway at 90 degrees, the BTV automatically disconnects when the aircraft groundspeed reduces to 10 knots. If the taxiway is a rapid-exit taxiwayTaxiway
A taxiway is a path on an airport connecting runways with ramps, hangars, terminals and other facilities. They mostly have hard surface such as asphalt or concrete, although smaller airports sometimes use gravel or grass....
, the BTV automatically disconnects at 40 to 50 knots groundspeed (depending on conditions).
Advantages
Proponents of the system point out that using BTV will reduce wear on brakes and tires (estimated at 20% reduction over present wear rates), less time that the aircraft spends within the active area of the runway, and enhanced ability to predict required cool-down time on the brakes (and thus to better control minimum gate turnaround time).The greatest potential advantage of the system is its ability to predict whether an aircraft will be able to stop safely on a specified runway. The pilot selects the runway and enters the reported surface conditions (wind direction, windspeed, wet or dry, cleared or slushy), and the computer uses stored runway information, computed aircraft weights and required approach speeds, and computed flare/touchdown characteristics to predict whether the stopping point will lie outside the runway's endpoint.
Inputs
The flight crew inputs the selected runway, and the reported runway surface conditions. The flight computer updates its calculations using predicted speed and wind conditions until the airplane is 500 feet (150 m) above the surface, after which it uses actual speed and wind inputs.Timeline
The BTV concept was born in a 1998 Ph.D. thesis by French engineer Fabrice Villaume, who became head of Airbus' BTV program and who holds patents on the process. Between 2002 and 2006 the computer routines were worked out, and the process was first tested on an Airbus A340Airbus A340
The Airbus A340 is a long-range four-engine wide-body commercial passenger jet airliner. Developed by Airbus Industrie,A consortium of European aerospace companies, Airbus is now fully owned by EADS and since 2001 has been known as Airbus SAS. a consortium of European aerospace companies, which is...
,
with the first test landing in that aircraft accomplished in March 2005. The first test landing of an A380 using the BTV system was performed in May 2008.
Airbus initially announced its plan to make the BTV system available by 2007, but the production bottlenecks that Airbus encountered in meeting the initial A380 delivery schedules apparently pushed back development of several such planned improvements. As of 2009 the company is seeking certification
Type certificate
A Type Certificate, is awarded by aviation regulating bodies to aerospace manufacturers after it has been established that the particular design of a civil aircraft, engine, or propeller has fulfilled the regulating bodies' current prevailing airworthiness requirements for the safe conduct of...
initially on the A380, after which it will announce planned incorporation schedules for other aircraft in the Airbus airliner product line. In 2006 Airbus indicated that following its introduction on the A380, the BTV "[would] be followed by retrofits available on all of other Airbus aircraft families." However, as of 2009 the company is indicating only that it will work on incorporating the feature on new A320s, and no definite availability schedule has been announced.
In 2005 Airbus also announced its intention to incorporate BTV into the upcoming Airbus A350
Airbus A350
The Airbus A350 is a family of long-range, wide-body jet airliners under development by European aircraft manufacturer Airbus.A consortium originally comprising European aerospace companies from the UK, France, Spain and West Germany, Airbus is now fully owned by EADS and since 2001 has been known...
. However, since then that project has suffered several redesign phases, and it is not clear whether the BTV will still be offered when the A350 does come to market.