Why is the A380’s with-reversers stopping distance the same as its no-reversers stopping distance?Why doesn't the A380 use its outboard thrust reversers?Why doesn't the A380 use its outboard thrust reversers?Do the engines still spool up when reverse thrust is selected, but the reversers are not deployed?Why do modern jetliners provide Thrust Reversers at all in their design decisions?What is the preferred way to slow down an airliner on a long runway?Why does an aircraft not spin out of control right after touch-down?Does the 747-8 / A380 nose-wheel encounter more weight during braking?Would installing 6 engines on an Airbus A380 and or Boeing 747-800 achieve a shorter take off distance?Why are landing-distance and rejected-takeoff certification tests performed without thrust reversers?Why do the 737-100/200’s thrust reversers blow fully open if hydraulic pressure is removed while the reversers are partly open?Why are thrust reversers not used to slow down to taxi speeds?
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Why is the A380’s with-reversers stopping distance the same as its no-reversers stopping distance?
Why doesn't the A380 use its outboard thrust reversers?Why doesn't the A380 use its outboard thrust reversers?Do the engines still spool up when reverse thrust is selected, but the reversers are not deployed?Why do modern jetliners provide Thrust Reversers at all in their design decisions?What is the preferred way to slow down an airliner on a long runway?Why does an aircraft not spin out of control right after touch-down?Does the 747-8 / A380 nose-wheel encounter more weight during braking?Would installing 6 engines on an Airbus A380 and or Boeing 747-800 achieve a shorter take off distance?Why are landing-distance and rejected-takeoff certification tests performed without thrust reversers?Why do the 737-100/200’s thrust reversers blow fully open if hydraulic pressure is removed while the reversers are partly open?Why are thrust reversers not used to slow down to taxi speeds?
$begingroup$
Thrust reversers, found on almost all jetliners1 and on the larger propliners, redirect engine thrust forwards, helping to slow the aircraft in the event of a landing or rejected takeoff.2 This takes some of the load off the aircraft’s wheelbrakes, reducing brakepad wear and tyre overheating, and considerably increases the total braking force available, allowing the aircraft to stop in a shorter distance than it otherwise would...3
...unless, that is, your aircraft is an A380, in which case, your reversers (all two of them), although they do reduce brake wear, apparently do not decrease the aircraft’s stopping distance (my emphasis):
The two reversers do help slow the A380—but not by much. In fact, unlike the thrust reversers on most airliners, including the Boeing 747 jumbo, they do not stop the aircraft in a shorter distance than brakes and spoilers alone. They do, however, take some of the strain off the brakes and are useful if water or snow makes the runway slippery.
How is this possible? Any increase in available braking force should shorten the aircraft’s stopping distance (even if only by a small amount), so, assuming that the A380’s reversers produce a nonzero amount of braking force, the stopping distance for a given A380 at a given weight on a given runway under given conditions using maximum wheelbraking, maximum aerobraking, and maximum reverse should still be less than the stopping distance for said A380 at said weight on said runway under said conditions using maximum wheelbraking and maximum aerobraking, but no reverse thrust.
Yet, apparently, it isn’t.
Would someone like to explain this?
1: The exceptions being the Fokker F28 and BAe 146.
2: A few jetliners, such as the DC-8, Il-62, and Concorde, can also use reverse thrust in flight, to steepen the aircraft’s descent angle without increasing its speed; in essence, the reversers are used as blown airbrakes.
3: This is especially important when wheelbrake effectiveness is degraded, due to, for instance, landing on a contaminated runway4 (which severely limits the amount of force that can be applied to the wheelbrakes without them locking up), with inoperative spoilers (which severely decreases the amount of weight carried by the wheels, and, thus, the amount by which their brakes can slow the aircraft), with one or more blown tyres (which renders the brakes on those wheel(s) useless for slowing the aircraft), overweight (which forces the aircraft to land at a much higher speed, where the coefficient of friction between the tyres and the runway is much lower than at lower speeds), with inoperative flaps and/or slats (ditto), with accreted ice and/or wing-leading-edge damage (ditto numero dos), with inoperative antiskid (which requires that the pilot(s) brake manually, and severely limit the amount of braking force [especially at high speeds] to prevent the wheels from locking up), with one or more inoperative wheelbrakes (for obvious reasons), numerous other things that I haven’t thought of, or any combination of the above.
4: For instance, one that is flooded (hopefully with water, not Jet A-1) or covered in (usually water) ice.
landing airbus-a380 thrust-reverser
asked May 15 at 2:15
SeanSean
7,10943392
$endgroup$
add a comment |
$begingroup$
Thrust reversers, found on almost all jetliners1 and on the larger propliners, redirect engine thrust forwards, helping to slow the aircraft in the event of a landing or rejected takeoff.2 This takes some of the load off the aircraft’s wheelbrakes, reducing brakepad wear and tyre overheating, and considerably increases the total braking force available, allowing the aircraft to stop in a shorter distance than it otherwise would...3
...unless, that is, your aircraft is an A380, in which case, your reversers (all two of them), although they do reduce brake wear, apparently do not decrease the aircraft’s stopping distance (my emphasis):
The two reversers do help slow the A380—but not by much. In fact, unlike the thrust reversers on most airliners, including the Boeing 747 jumbo, they do not stop the aircraft in a shorter distance than brakes and spoilers alone. They do, however, take some of the strain off the brakes and are useful if water or snow makes the runway slippery.
How is this possible? Any increase in available braking force should shorten the aircraft’s stopping distance (even if only by a small amount), so, assuming that the A380’s reversers produce a nonzero amount of braking force, the stopping distance for a given A380 at a given weight on a given runway under given conditions using maximum wheelbraking, maximum aerobraking, and maximum reverse should still be less than the stopping distance for said A380 at said weight on said runway under said conditions using maximum wheelbraking and maximum aerobraking, but no reverse thrust.
Yet, apparently, it isn’t.
Would someone like to explain this?
1: The exceptions being the Fokker F28 and BAe 146.
2: A few jetliners, such as the DC-8, Il-62, and Concorde, can also use reverse thrust in flight, to steepen the aircraft’s descent angle without increasing its speed; in essence, the reversers are used as blown airbrakes.
3: This is especially important when wheelbrake effectiveness is degraded, due to, for instance, landing on a contaminated runway4 (which severely limits the amount of force that can be applied to the wheelbrakes without them locking up), with inoperative spoilers (which severely decreases the amount of weight carried by the wheels, and, thus, the amount by which their brakes can slow the aircraft), with one or more blown tyres (which renders the brakes on those wheel(s) useless for slowing the aircraft), overweight (which forces the aircraft to land at a much higher speed, where the coefficient of friction between the tyres and the runway is much lower than at lower speeds), with inoperative flaps and/or slats (ditto), with accreted ice and/or wing-leading-edge damage (ditto numero dos), with inoperative antiskid (which requires that the pilot(s) brake manually, and severely limit the amount of braking force [especially at high speeds] to prevent the wheels from locking up), with one or more inoperative wheelbrakes (for obvious reasons), numerous other things that I haven’t thought of, or any combination of the above.
4: For instance, one that is flooded (hopefully with water, not Jet A-1) or covered in (usually water) ice.
landing airbus-a380 thrust-reverser
asked May 15 at 2:15
SeanSean
7,10943392
$endgroup$
2
$begingroup$
I suspect it would be different in case of an emergency braking
$endgroup$
– Antzi
May 15 at 2:51
4
$begingroup$
You're giving too much credence to one isolated statement by one reporter in one article. Typically, stopping performance is a matter of a selected deceleration rate - achieved this some brakes + reverse, of more braking & less reverse. Hence, a "no difference" case. I strongly suspect that author's statement wouldn't prove out with a dive into the A380's performance tables.
$endgroup$
– Ralph J
May 15 at 3:20
add a comment |
$begingroup$
Thrust reversers, found on almost all jetliners1 and on the larger propliners, redirect engine thrust forwards, helping to slow the aircraft in the event of a landing or rejected takeoff.2 This takes some of the load off the aircraft’s wheelbrakes, reducing brakepad wear and tyre overheating, and considerably increases the total braking force available, allowing the aircraft to stop in a shorter distance than it otherwise would...3
...unless, that is, your aircraft is an A380, in which case, your reversers (all two of them), although they do reduce brake wear, apparently do not decrease the aircraft’s stopping distance (my emphasis):
The two reversers do help slow the A380—but not by much. In fact, unlike the thrust reversers on most airliners, including the Boeing 747 jumbo, they do not stop the aircraft in a shorter distance than brakes and spoilers alone. They do, however, take some of the strain off the brakes and are useful if water or snow makes the runway slippery.
How is this possible? Any increase in available braking force should shorten the aircraft’s stopping distance (even if only by a small amount), so, assuming that the A380’s reversers produce a nonzero amount of braking force, the stopping distance for a given A380 at a given weight on a given runway under given conditions using maximum wheelbraking, maximum aerobraking, and maximum reverse should still be less than the stopping distance for said A380 at said weight on said runway under said conditions using maximum wheelbraking and maximum aerobraking, but no reverse thrust.
Yet, apparently, it isn’t.
Would someone like to explain this?
1: The exceptions being the Fokker F28 and BAe 146.
2: A few jetliners, such as the DC-8, Il-62, and Concorde, can also use reverse thrust in flight, to steepen the aircraft’s descent angle without increasing its speed; in essence, the reversers are used as blown airbrakes.
3: This is especially important when wheelbrake effectiveness is degraded, due to, for instance, landing on a contaminated runway4 (which severely limits the amount of force that can be applied to the wheelbrakes without them locking up), with inoperative spoilers (which severely decreases the amount of weight carried by the wheels, and, thus, the amount by which their brakes can slow the aircraft), with one or more blown tyres (which renders the brakes on those wheel(s) useless for slowing the aircraft), overweight (which forces the aircraft to land at a much higher speed, where the coefficient of friction between the tyres and the runway is much lower than at lower speeds), with inoperative flaps and/or slats (ditto), with accreted ice and/or wing-leading-edge damage (ditto numero dos), with inoperative antiskid (which requires that the pilot(s) brake manually, and severely limit the amount of braking force [especially at high speeds] to prevent the wheels from locking up), with one or more inoperative wheelbrakes (for obvious reasons), numerous other things that I haven’t thought of, or any combination of the above.
4: For instance, one that is flooded (hopefully with water, not Jet A-1) or covered in (usually water) ice.
landing airbus-a380 thrust-reverser
asked May 15 at 2:15
SeanSean
7,10943392
$endgroup$
Thrust reversers, found on almost all jetliners1 and on the larger propliners, redirect engine thrust forwards, helping to slow the aircraft in the event of a landing or rejected takeoff.2 This takes some of the load off the aircraft’s wheelbrakes, reducing brakepad wear and tyre overheating, and considerably increases the total braking force available, allowing the aircraft to stop in a shorter distance than it otherwise would...3
...unless, that is, your aircraft is an A380, in which case, your reversers (all two of them), although they do reduce brake wear, apparently do not decrease the aircraft’s stopping distance (my emphasis):
The two reversers do help slow the A380—but not by much. In fact, unlike the thrust reversers on most airliners, including the Boeing 747 jumbo, they do not stop the aircraft in a shorter distance than brakes and spoilers alone. They do, however, take some of the strain off the brakes and are useful if water or snow makes the runway slippery.
How is this possible? Any increase in available braking force should shorten the aircraft’s stopping distance (even if only by a small amount), so, assuming that the A380’s reversers produce a nonzero amount of braking force, the stopping distance for a given A380 at a given weight on a given runway under given conditions using maximum wheelbraking, maximum aerobraking, and maximum reverse should still be less than the stopping distance for said A380 at said weight on said runway under said conditions using maximum wheelbraking and maximum aerobraking, but no reverse thrust.
Yet, apparently, it isn’t.
Would someone like to explain this?
1: The exceptions being the Fokker F28 and BAe 146.
2: A few jetliners, such as the DC-8, Il-62, and Concorde, can also use reverse thrust in flight, to steepen the aircraft’s descent angle without increasing its speed; in essence, the reversers are used as blown airbrakes.
3: This is especially important when wheelbrake effectiveness is degraded, due to, for instance, landing on a contaminated runway4 (which severely limits the amount of force that can be applied to the wheelbrakes without them locking up), with inoperative spoilers (which severely decreases the amount of weight carried by the wheels, and, thus, the amount by which their brakes can slow the aircraft), with one or more blown tyres (which renders the brakes on those wheel(s) useless for slowing the aircraft), overweight (which forces the aircraft to land at a much higher speed, where the coefficient of friction between the tyres and the runway is much lower than at lower speeds), with inoperative flaps and/or slats (ditto), with accreted ice and/or wing-leading-edge damage (ditto numero dos), with inoperative antiskid (which requires that the pilot(s) brake manually, and severely limit the amount of braking force [especially at high speeds] to prevent the wheels from locking up), with one or more inoperative wheelbrakes (for obvious reasons), numerous other things that I haven’t thought of, or any combination of the above.
4: For instance, one that is flooded (hopefully with water, not Jet A-1) or covered in (usually water) ice.
landing airbus-a380 thrust-reverser
landing airbus-a380 thrust-reverser
asked May 15 at 2:15
SeanSean
7,10943392
asked May 15 at 2:15
SeanSean
7,10943392
asked May 15 at 2:15
SeanSean
7,10943392
asked May 15 at 2:15
SeanSean
7,10943392
asked May 15 at 2:15
SeanSean
7,10943392
7,10943392
2
$begingroup$
I suspect it would be different in case of an emergency braking
$endgroup$
– Antzi
May 15 at 2:51
4
$begingroup$
You're giving too much credence to one isolated statement by one reporter in one article. Typically, stopping performance is a matter of a selected deceleration rate - achieved this some brakes + reverse, of more braking & less reverse. Hence, a "no difference" case. I strongly suspect that author's statement wouldn't prove out with a dive into the A380's performance tables.
$endgroup$
– Ralph J
May 15 at 3:20
add a comment |
2
$begingroup$
I suspect it would be different in case of an emergency braking
$endgroup$
– Antzi
May 15 at 2:51
4
$begingroup$
You're giving too much credence to one isolated statement by one reporter in one article. Typically, stopping performance is a matter of a selected deceleration rate - achieved this some brakes + reverse, of more braking & less reverse. Hence, a "no difference" case. I strongly suspect that author's statement wouldn't prove out with a dive into the A380's performance tables.
$endgroup$
– Ralph J
May 15 at 3:20
2
2
$begingroup$
I suspect it would be different in case of an emergency braking
$endgroup$
– Antzi
May 15 at 2:51
$begingroup$
I suspect it would be different in case of an emergency braking
$endgroup$
– Antzi
May 15 at 2:51
4
4
$begingroup$
You're giving too much credence to one isolated statement by one reporter in one article. Typically, stopping performance is a matter of a selected deceleration rate - achieved this some brakes + reverse, of more braking & less reverse. Hence, a "no difference" case. I strongly suspect that author's statement wouldn't prove out with a dive into the A380's performance tables.
$endgroup$
– Ralph J
May 15 at 3:20
$begingroup$
You're giving too much credence to one isolated statement by one reporter in one article. Typically, stopping performance is a matter of a selected deceleration rate - achieved this some brakes + reverse, of more braking & less reverse. Hence, a "no difference" case. I strongly suspect that author's statement wouldn't prove out with a dive into the A380's performance tables.
$endgroup$
– Ralph J
May 15 at 3:20
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
In all Airbuses auto-braking system aims for specific deceleration. Once the design target has been reached, the system does not apply more brake pressure although there usually is more available. So, if you apply thrust reverser with autobrake selected it will apply less pressure on wheel brakes and as the target deceleration remains the same, the stopping distance remains unaffected.
On slippery runways the autobrakes apply brakes until anti-skid starts to limit the brake pressure so in those conditions reverser would shorten the stopping distance. This would also apply to rejected take-off where maximum braking is commanded.
answered May 15 at 3:34
busdriverbusdriver
1,07811
$endgroup$
2
$begingroup$
And this cannot be overridden by the pilot in case of an emergency, to brake faster, no matter the wear on the brakes?
$endgroup$
– vsz
May 15 at 10:29
4
$begingroup$
@vsz why would locking up the wheels, or overheating the brakes and degrading their efficiency (possibly to zero), make the plane stop quicker?
$endgroup$
– alephzero
May 15 at 12:06
5
$begingroup$
@alephzero I think he means running the breaks at the limits (no locking/overheating), with maximum thrust through the reversers.
$endgroup$
– Baldrickk
May 15 at 12:14
3
$begingroup$
@vsz With autobrakes, no. But of course pilot can step on the brakes anytime and he’ll get full manual braking with anti-skid. Manual operation of brake pedals will disconnect autobrakes.
$endgroup$
– busdriver
May 15 at 12:33
2
$begingroup$
@Joshua Not if the reject is because an outboard engine (on the A380, anyway) failed! Or due to a predictive windshear warning, or a vehicle on the runway, or a cargo fire warning, or etc... Of course, the worst-case planning assumes no reverse during the RTO, but it's entirely possible that it may be available.
$endgroup$
– Ralph J
May 15 at 18:23
|
show 3 more comments
$begingroup$
The A380 has an optional system called Brake-To-Vacate (BTV) which allows the flight crew to calculate required runway length and determine which runway exit they can make before starting descent. Once engaged, the pilot just has to put the aircraft on the runway and BTV takes over, applying spoilers and thrust reversers ahead of brakes to achieve the desired landing performance.
There's a more detailed look at the system here
Stopping performance for certification has to be determined without the use of thrust reversers, so the use of thrust reverser in service doesn't change that particular aspect of the aircraft's certified performance..
answered May 15 at 2:50
Redd HerringRedd Herring
2318
$endgroup$
4
$begingroup$
To clarify, BTV does not automatically deploy spoilers or thrust reversers. For those, a pilot action is always required. Indeed, BTV is a function of autobrake which in turn does not activate until spoilers are deployed. More over, it is true that thrust reversers are not taken into account when certifying performance on dry runways, but they do have effect.
$endgroup$
– busdriver
May 15 at 5:08
add a comment |
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2 Answers
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active
oldest
votes
2 Answers
2
active
oldest
votes
active
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votes
active
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votes
$begingroup$
In all Airbuses auto-braking system aims for specific deceleration. Once the design target has been reached, the system does not apply more brake pressure although there usually is more available. So, if you apply thrust reverser with autobrake selected it will apply less pressure on wheel brakes and as the target deceleration remains the same, the stopping distance remains unaffected.
On slippery runways the autobrakes apply brakes until anti-skid starts to limit the brake pressure so in those conditions reverser would shorten the stopping distance. This would also apply to rejected take-off where maximum braking is commanded.
answered May 15 at 3:34
busdriverbusdriver
1,07811
$endgroup$
2
$begingroup$
And this cannot be overridden by the pilot in case of an emergency, to brake faster, no matter the wear on the brakes?
$endgroup$
– vsz
May 15 at 10:29
4
$begingroup$
@vsz why would locking up the wheels, or overheating the brakes and degrading their efficiency (possibly to zero), make the plane stop quicker?
$endgroup$
– alephzero
May 15 at 12:06
5
$begingroup$
@alephzero I think he means running the breaks at the limits (no locking/overheating), with maximum thrust through the reversers.
$endgroup$
– Baldrickk
May 15 at 12:14
3
$begingroup$
@vsz With autobrakes, no. But of course pilot can step on the brakes anytime and he’ll get full manual braking with anti-skid. Manual operation of brake pedals will disconnect autobrakes.
$endgroup$
– busdriver
May 15 at 12:33
2
$begingroup$
@Joshua Not if the reject is because an outboard engine (on the A380, anyway) failed! Or due to a predictive windshear warning, or a vehicle on the runway, or a cargo fire warning, or etc... Of course, the worst-case planning assumes no reverse during the RTO, but it's entirely possible that it may be available.
$endgroup$
– Ralph J
May 15 at 18:23
|
show 3 more comments
$begingroup$
In all Airbuses auto-braking system aims for specific deceleration. Once the design target has been reached, the system does not apply more brake pressure although there usually is more available. So, if you apply thrust reverser with autobrake selected it will apply less pressure on wheel brakes and as the target deceleration remains the same, the stopping distance remains unaffected.
On slippery runways the autobrakes apply brakes until anti-skid starts to limit the brake pressure so in those conditions reverser would shorten the stopping distance. This would also apply to rejected take-off where maximum braking is commanded.
answered May 15 at 3:34
busdriverbusdriver
1,07811
$endgroup$
2
$begingroup$
And this cannot be overridden by the pilot in case of an emergency, to brake faster, no matter the wear on the brakes?
$endgroup$
– vsz
May 15 at 10:29
4
$begingroup$
@vsz why would locking up the wheels, or overheating the brakes and degrading their efficiency (possibly to zero), make the plane stop quicker?
$endgroup$
– alephzero
May 15 at 12:06
5
$begingroup$
@alephzero I think he means running the breaks at the limits (no locking/overheating), with maximum thrust through the reversers.
$endgroup$
– Baldrickk
May 15 at 12:14
3
$begingroup$
@vsz With autobrakes, no. But of course pilot can step on the brakes anytime and he’ll get full manual braking with anti-skid. Manual operation of brake pedals will disconnect autobrakes.
$endgroup$
– busdriver
May 15 at 12:33
2
$begingroup$
@Joshua Not if the reject is because an outboard engine (on the A380, anyway) failed! Or due to a predictive windshear warning, or a vehicle on the runway, or a cargo fire warning, or etc... Of course, the worst-case planning assumes no reverse during the RTO, but it's entirely possible that it may be available.
$endgroup$
– Ralph J
May 15 at 18:23
|
show 3 more comments
$begingroup$
In all Airbuses auto-braking system aims for specific deceleration. Once the design target has been reached, the system does not apply more brake pressure although there usually is more available. So, if you apply thrust reverser with autobrake selected it will apply less pressure on wheel brakes and as the target deceleration remains the same, the stopping distance remains unaffected.
On slippery runways the autobrakes apply brakes until anti-skid starts to limit the brake pressure so in those conditions reverser would shorten the stopping distance. This would also apply to rejected take-off where maximum braking is commanded.
answered May 15 at 3:34
busdriverbusdriver
1,07811
$endgroup$
In all Airbuses auto-braking system aims for specific deceleration. Once the design target has been reached, the system does not apply more brake pressure although there usually is more available. So, if you apply thrust reverser with autobrake selected it will apply less pressure on wheel brakes and as the target deceleration remains the same, the stopping distance remains unaffected.
On slippery runways the autobrakes apply brakes until anti-skid starts to limit the brake pressure so in those conditions reverser would shorten the stopping distance. This would also apply to rejected take-off where maximum braking is commanded.
answered May 15 at 3:34
busdriverbusdriver
1,07811
answered May 15 at 3:34
busdriverbusdriver
1,07811
answered May 15 at 3:34
busdriverbusdriver
1,07811
answered May 15 at 3:34
busdriverbusdriver
1,07811
1,07811
2
$begingroup$
And this cannot be overridden by the pilot in case of an emergency, to brake faster, no matter the wear on the brakes?
$endgroup$
– vsz
May 15 at 10:29
4
$begingroup$
@vsz why would locking up the wheels, or overheating the brakes and degrading their efficiency (possibly to zero), make the plane stop quicker?
$endgroup$
– alephzero
May 15 at 12:06
5
$begingroup$
@alephzero I think he means running the breaks at the limits (no locking/overheating), with maximum thrust through the reversers.
$endgroup$
– Baldrickk
May 15 at 12:14
3
$begingroup$
@vsz With autobrakes, no. But of course pilot can step on the brakes anytime and he’ll get full manual braking with anti-skid. Manual operation of brake pedals will disconnect autobrakes.
$endgroup$
– busdriver
May 15 at 12:33
2
$begingroup$
@Joshua Not if the reject is because an outboard engine (on the A380, anyway) failed! Or due to a predictive windshear warning, or a vehicle on the runway, or a cargo fire warning, or etc... Of course, the worst-case planning assumes no reverse during the RTO, but it's entirely possible that it may be available.
$endgroup$
– Ralph J
May 15 at 18:23
|
show 3 more comments
2
$begingroup$
And this cannot be overridden by the pilot in case of an emergency, to brake faster, no matter the wear on the brakes?
$endgroup$
– vsz
May 15 at 10:29
4
$begingroup$
@vsz why would locking up the wheels, or overheating the brakes and degrading their efficiency (possibly to zero), make the plane stop quicker?
$endgroup$
– alephzero
May 15 at 12:06
5
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@alephzero I think he means running the breaks at the limits (no locking/overheating), with maximum thrust through the reversers.
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– Baldrickk
May 15 at 12:14
3
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@vsz With autobrakes, no. But of course pilot can step on the brakes anytime and he’ll get full manual braking with anti-skid. Manual operation of brake pedals will disconnect autobrakes.
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– busdriver
May 15 at 12:33
2
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@Joshua Not if the reject is because an outboard engine (on the A380, anyway) failed! Or due to a predictive windshear warning, or a vehicle on the runway, or a cargo fire warning, or etc... Of course, the worst-case planning assumes no reverse during the RTO, but it's entirely possible that it may be available.
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– Ralph J
May 15 at 18:23
2
2
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And this cannot be overridden by the pilot in case of an emergency, to brake faster, no matter the wear on the brakes?
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– vsz
May 15 at 10:29
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And this cannot be overridden by the pilot in case of an emergency, to brake faster, no matter the wear on the brakes?
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– vsz
May 15 at 10:29
4
4
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@vsz why would locking up the wheels, or overheating the brakes and degrading their efficiency (possibly to zero), make the plane stop quicker?
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– alephzero
May 15 at 12:06
$begingroup$
@vsz why would locking up the wheels, or overheating the brakes and degrading their efficiency (possibly to zero), make the plane stop quicker?
$endgroup$
– alephzero
May 15 at 12:06
5
5
$begingroup$
@alephzero I think he means running the breaks at the limits (no locking/overheating), with maximum thrust through the reversers.
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– Baldrickk
May 15 at 12:14
$begingroup$
@alephzero I think he means running the breaks at the limits (no locking/overheating), with maximum thrust through the reversers.
$endgroup$
– Baldrickk
May 15 at 12:14
3
3
$begingroup$
@vsz With autobrakes, no. But of course pilot can step on the brakes anytime and he’ll get full manual braking with anti-skid. Manual operation of brake pedals will disconnect autobrakes.
$endgroup$
– busdriver
May 15 at 12:33
$begingroup$
@vsz With autobrakes, no. But of course pilot can step on the brakes anytime and he’ll get full manual braking with anti-skid. Manual operation of brake pedals will disconnect autobrakes.
$endgroup$
– busdriver
May 15 at 12:33
2
2
$begingroup$
@Joshua Not if the reject is because an outboard engine (on the A380, anyway) failed! Or due to a predictive windshear warning, or a vehicle on the runway, or a cargo fire warning, or etc... Of course, the worst-case planning assumes no reverse during the RTO, but it's entirely possible that it may be available.
$endgroup$
– Ralph J
May 15 at 18:23
$begingroup$
@Joshua Not if the reject is because an outboard engine (on the A380, anyway) failed! Or due to a predictive windshear warning, or a vehicle on the runway, or a cargo fire warning, or etc... Of course, the worst-case planning assumes no reverse during the RTO, but it's entirely possible that it may be available.
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– Ralph J
May 15 at 18:23
|
show 3 more comments
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The A380 has an optional system called Brake-To-Vacate (BTV) which allows the flight crew to calculate required runway length and determine which runway exit they can make before starting descent. Once engaged, the pilot just has to put the aircraft on the runway and BTV takes over, applying spoilers and thrust reversers ahead of brakes to achieve the desired landing performance.
There's a more detailed look at the system here
Stopping performance for certification has to be determined without the use of thrust reversers, so the use of thrust reverser in service doesn't change that particular aspect of the aircraft's certified performance..
answered May 15 at 2:50
Redd HerringRedd Herring
2318
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4
$begingroup$
To clarify, BTV does not automatically deploy spoilers or thrust reversers. For those, a pilot action is always required. Indeed, BTV is a function of autobrake which in turn does not activate until spoilers are deployed. More over, it is true that thrust reversers are not taken into account when certifying performance on dry runways, but they do have effect.
$endgroup$
– busdriver
May 15 at 5:08
add a comment |
$begingroup$
The A380 has an optional system called Brake-To-Vacate (BTV) which allows the flight crew to calculate required runway length and determine which runway exit they can make before starting descent. Once engaged, the pilot just has to put the aircraft on the runway and BTV takes over, applying spoilers and thrust reversers ahead of brakes to achieve the desired landing performance.
There's a more detailed look at the system here
Stopping performance for certification has to be determined without the use of thrust reversers, so the use of thrust reverser in service doesn't change that particular aspect of the aircraft's certified performance..
answered May 15 at 2:50
Redd HerringRedd Herring
2318
$endgroup$
4
$begingroup$
To clarify, BTV does not automatically deploy spoilers or thrust reversers. For those, a pilot action is always required. Indeed, BTV is a function of autobrake which in turn does not activate until spoilers are deployed. More over, it is true that thrust reversers are not taken into account when certifying performance on dry runways, but they do have effect.
$endgroup$
– busdriver
May 15 at 5:08
add a comment |
$begingroup$
The A380 has an optional system called Brake-To-Vacate (BTV) which allows the flight crew to calculate required runway length and determine which runway exit they can make before starting descent. Once engaged, the pilot just has to put the aircraft on the runway and BTV takes over, applying spoilers and thrust reversers ahead of brakes to achieve the desired landing performance.
There's a more detailed look at the system here
Stopping performance for certification has to be determined without the use of thrust reversers, so the use of thrust reverser in service doesn't change that particular aspect of the aircraft's certified performance..
answered May 15 at 2:50
Redd HerringRedd Herring
2318
$endgroup$
The A380 has an optional system called Brake-To-Vacate (BTV) which allows the flight crew to calculate required runway length and determine which runway exit they can make before starting descent. Once engaged, the pilot just has to put the aircraft on the runway and BTV takes over, applying spoilers and thrust reversers ahead of brakes to achieve the desired landing performance.
There's a more detailed look at the system here
Stopping performance for certification has to be determined without the use of thrust reversers, so the use of thrust reverser in service doesn't change that particular aspect of the aircraft's certified performance..
answered May 15 at 2:50
Redd HerringRedd Herring
2318
answered May 15 at 2:50
Redd HerringRedd Herring
2318
answered May 15 at 2:50
Redd HerringRedd Herring
2318
answered May 15 at 2:50
Redd HerringRedd Herring
2318
2318
4
$begingroup$
To clarify, BTV does not automatically deploy spoilers or thrust reversers. For those, a pilot action is always required. Indeed, BTV is a function of autobrake which in turn does not activate until spoilers are deployed. More over, it is true that thrust reversers are not taken into account when certifying performance on dry runways, but they do have effect.
$endgroup$
– busdriver
May 15 at 5:08
add a comment |
4
$begingroup$
To clarify, BTV does not automatically deploy spoilers or thrust reversers. For those, a pilot action is always required. Indeed, BTV is a function of autobrake which in turn does not activate until spoilers are deployed. More over, it is true that thrust reversers are not taken into account when certifying performance on dry runways, but they do have effect.
$endgroup$
– busdriver
May 15 at 5:08
4
4
$begingroup$
To clarify, BTV does not automatically deploy spoilers or thrust reversers. For those, a pilot action is always required. Indeed, BTV is a function of autobrake which in turn does not activate until spoilers are deployed. More over, it is true that thrust reversers are not taken into account when certifying performance on dry runways, but they do have effect.
$endgroup$
– busdriver
May 15 at 5:08
$begingroup$
To clarify, BTV does not automatically deploy spoilers or thrust reversers. For those, a pilot action is always required. Indeed, BTV is a function of autobrake which in turn does not activate until spoilers are deployed. More over, it is true that thrust reversers are not taken into account when certifying performance on dry runways, but they do have effect.
$endgroup$
– busdriver
May 15 at 5:08
add a comment |
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I suspect it would be different in case of an emergency braking
$endgroup$
– Antzi
May 15 at 2:51
4
$begingroup$
You're giving too much credence to one isolated statement by one reporter in one article. Typically, stopping performance is a matter of a selected deceleration rate - achieved this some brakes + reverse, of more braking & less reverse. Hence, a "no difference" case. I strongly suspect that author's statement wouldn't prove out with a dive into the A380's performance tables.
$endgroup$
– Ralph J
May 15 at 3:20