Why is indicated airspeed rather than ground speed used during the takeoff roll?
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My instructor asked me this question during my lesson and I couldn't come up with any answers. He asked why do I need to look at the indicated airspeed rather than ground speed when in takeoff roll or as soon as we touchdown? There is this procedure in my airline that we have to call out airspeeds when we are rolling for takeoff (ex: "80 kts" before THR HOLD).
It would be great if you could give me the reference to back it up.
takeoff airspeed
edited yesterday
ymb1
67.4k7213357
asked yesterday
SteveSteve
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show 19 more comments
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My instructor asked me this question during my lesson and I couldn't come up with any answers. He asked why do I need to look at the indicated airspeed rather than ground speed when in takeoff roll or as soon as we touchdown? There is this procedure in my airline that we have to call out airspeeds when we are rolling for takeoff (ex: "80 kts" before THR HOLD).
It would be great if you could give me the reference to back it up.
takeoff airspeed
edited yesterday
ymb1
67.4k7213357
asked yesterday
SteveSteve
3812
New contributor
Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
57
$begingroup$
It seems you are a commercial pilot working at an airline and being trained on a new aircraft type. If that is true, I find it hard to believe that you don't understand the difference between indicated airspeed and ground speed.
$endgroup$
– Mike Sowsun
yesterday
9
$begingroup$
@Kittoes0124 The point is valid. I think anyone involved with aircraft would find it unsettling to see someone training at this level of professional aviation who could not answer this extremely basic question. The only logical conclusion is that either OP is the one trolling HNQ with a sensational question OR they represent a serious danger to the flying public and, hopefully, received a clear and unapologetic failing grade from their instructor.
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– J...
13 hours ago
10
$begingroup$
As someone who only has a little reading and no practical training on the subject I knew the answer from the title. A novice may not, but then you get to the word "airline" and a description of regular practice. That suggests a few possibilities: Trolling, story-telling in the name of an instructive but basic question (sometimes seen on other sites in the network), mistranslation (but the Q reads like it was written by a native speaker), or a pilot who somehow qualified without knowing much about aerodynamics. The reader can draw their own conclusion as to which one applies (@Kittoes0124)
$endgroup$
– Chris H
12 hours ago
12
$begingroup$
@Kittoes0124 Day 1 of somebody's flying training isn't compatible with "the procedure in my airline." There's nothing at all wrong with asking basic questions but asking basic questions while claiming to be a professional in a safety-critical job is something completely different. If the asker is in the position they claim to be in, they should have known the answer to this question long ago. Random member of the public asks why surgeons wash their hands? Fine. Somebody says "I took a shower this morning but, in my hospital, procedure is we should wash our hands before surgery -- why?" Problem
$endgroup$
– David Richerby
11 hours ago
8
$begingroup$
@Kittoes0124 There's enough information (THR HOLD @ 80kts) to guess that OP is training in some type of Boeing passenger jet, likely a 737. Mike's comment does not express negativity, only justifiable disbelief that someone could be at the yoke of such an aircraft, in training or otherwise, without knowing which speed indicator to look at (or why!) during critical phases of flight. Even a student at this level should be able to answer this question without effort or hesitation. The only thing expressed here is scepticism that this is an honest question.
$endgroup$
– J...
10 hours ago
|
show 19 more comments
$begingroup$
My instructor asked me this question during my lesson and I couldn't come up with any answers. He asked why do I need to look at the indicated airspeed rather than ground speed when in takeoff roll or as soon as we touchdown? There is this procedure in my airline that we have to call out airspeeds when we are rolling for takeoff (ex: "80 kts" before THR HOLD).
It would be great if you could give me the reference to back it up.
takeoff airspeed
edited yesterday
ymb1
67.4k7213357
asked yesterday
SteveSteve
3812
New contributor
Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
My instructor asked me this question during my lesson and I couldn't come up with any answers. He asked why do I need to look at the indicated airspeed rather than ground speed when in takeoff roll or as soon as we touchdown? There is this procedure in my airline that we have to call out airspeeds when we are rolling for takeoff (ex: "80 kts" before THR HOLD).
It would be great if you could give me the reference to back it up.
takeoff airspeed
takeoff airspeed
edited yesterday
ymb1
67.4k7213357
asked yesterday
SteveSteve
3812
New contributor
Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited yesterday
ymb1
67.4k7213357
asked yesterday
SteveSteve
3812
New contributor
Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
edited yesterday
ymb1
67.4k7213357
edited yesterday
ymb1
67.4k7213357
edited yesterday
ymb1
67.4k7213357
67.4k7213357
asked yesterday
SteveSteve
3812
New contributor
Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
asked yesterday
SteveSteve
3812
asked yesterday
SteveSteve
3812
3812
New contributor
Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Steve is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
57
$begingroup$
It seems you are a commercial pilot working at an airline and being trained on a new aircraft type. If that is true, I find it hard to believe that you don't understand the difference between indicated airspeed and ground speed.
$endgroup$
– Mike Sowsun
yesterday
9
$begingroup$
@Kittoes0124 The point is valid. I think anyone involved with aircraft would find it unsettling to see someone training at this level of professional aviation who could not answer this extremely basic question. The only logical conclusion is that either OP is the one trolling HNQ with a sensational question OR they represent a serious danger to the flying public and, hopefully, received a clear and unapologetic failing grade from their instructor.
$endgroup$
– J...
13 hours ago
10
$begingroup$
As someone who only has a little reading and no practical training on the subject I knew the answer from the title. A novice may not, but then you get to the word "airline" and a description of regular practice. That suggests a few possibilities: Trolling, story-telling in the name of an instructive but basic question (sometimes seen on other sites in the network), mistranslation (but the Q reads like it was written by a native speaker), or a pilot who somehow qualified without knowing much about aerodynamics. The reader can draw their own conclusion as to which one applies (@Kittoes0124)
$endgroup$
– Chris H
12 hours ago
12
$begingroup$
@Kittoes0124 Day 1 of somebody's flying training isn't compatible with "the procedure in my airline." There's nothing at all wrong with asking basic questions but asking basic questions while claiming to be a professional in a safety-critical job is something completely different. If the asker is in the position they claim to be in, they should have known the answer to this question long ago. Random member of the public asks why surgeons wash their hands? Fine. Somebody says "I took a shower this morning but, in my hospital, procedure is we should wash our hands before surgery -- why?" Problem
$endgroup$
– David Richerby
11 hours ago
8
$begingroup$
@Kittoes0124 There's enough information (THR HOLD @ 80kts) to guess that OP is training in some type of Boeing passenger jet, likely a 737. Mike's comment does not express negativity, only justifiable disbelief that someone could be at the yoke of such an aircraft, in training or otherwise, without knowing which speed indicator to look at (or why!) during critical phases of flight. Even a student at this level should be able to answer this question without effort or hesitation. The only thing expressed here is scepticism that this is an honest question.
$endgroup$
– J...
10 hours ago
|
show 19 more comments
57
$begingroup$
It seems you are a commercial pilot working at an airline and being trained on a new aircraft type. If that is true, I find it hard to believe that you don't understand the difference between indicated airspeed and ground speed.
$endgroup$
– Mike Sowsun
yesterday
9
$begingroup$
@Kittoes0124 The point is valid. I think anyone involved with aircraft would find it unsettling to see someone training at this level of professional aviation who could not answer this extremely basic question. The only logical conclusion is that either OP is the one trolling HNQ with a sensational question OR they represent a serious danger to the flying public and, hopefully, received a clear and unapologetic failing grade from their instructor.
$endgroup$
– J...
13 hours ago
10
$begingroup$
As someone who only has a little reading and no practical training on the subject I knew the answer from the title. A novice may not, but then you get to the word "airline" and a description of regular practice. That suggests a few possibilities: Trolling, story-telling in the name of an instructive but basic question (sometimes seen on other sites in the network), mistranslation (but the Q reads like it was written by a native speaker), or a pilot who somehow qualified without knowing much about aerodynamics. The reader can draw their own conclusion as to which one applies (@Kittoes0124)
$endgroup$
– Chris H
12 hours ago
12
$begingroup$
@Kittoes0124 Day 1 of somebody's flying training isn't compatible with "the procedure in my airline." There's nothing at all wrong with asking basic questions but asking basic questions while claiming to be a professional in a safety-critical job is something completely different. If the asker is in the position they claim to be in, they should have known the answer to this question long ago. Random member of the public asks why surgeons wash their hands? Fine. Somebody says "I took a shower this morning but, in my hospital, procedure is we should wash our hands before surgery -- why?" Problem
$endgroup$
– David Richerby
11 hours ago
8
$begingroup$
@Kittoes0124 There's enough information (THR HOLD @ 80kts) to guess that OP is training in some type of Boeing passenger jet, likely a 737. Mike's comment does not express negativity, only justifiable disbelief that someone could be at the yoke of such an aircraft, in training or otherwise, without knowing which speed indicator to look at (or why!) during critical phases of flight. Even a student at this level should be able to answer this question without effort or hesitation. The only thing expressed here is scepticism that this is an honest question.
$endgroup$
– J...
10 hours ago
57
57
$begingroup$
It seems you are a commercial pilot working at an airline and being trained on a new aircraft type. If that is true, I find it hard to believe that you don't understand the difference between indicated airspeed and ground speed.
$endgroup$
– Mike Sowsun
yesterday
$begingroup$
It seems you are a commercial pilot working at an airline and being trained on a new aircraft type. If that is true, I find it hard to believe that you don't understand the difference between indicated airspeed and ground speed.
$endgroup$
– Mike Sowsun
yesterday
9
9
$begingroup$
@Kittoes0124 The point is valid. I think anyone involved with aircraft would find it unsettling to see someone training at this level of professional aviation who could not answer this extremely basic question. The only logical conclusion is that either OP is the one trolling HNQ with a sensational question OR they represent a serious danger to the flying public and, hopefully, received a clear and unapologetic failing grade from their instructor.
$endgroup$
– J...
13 hours ago
$begingroup$
@Kittoes0124 The point is valid. I think anyone involved with aircraft would find it unsettling to see someone training at this level of professional aviation who could not answer this extremely basic question. The only logical conclusion is that either OP is the one trolling HNQ with a sensational question OR they represent a serious danger to the flying public and, hopefully, received a clear and unapologetic failing grade from their instructor.
$endgroup$
– J...
13 hours ago
10
10
$begingroup$
As someone who only has a little reading and no practical training on the subject I knew the answer from the title. A novice may not, but then you get to the word "airline" and a description of regular practice. That suggests a few possibilities: Trolling, story-telling in the name of an instructive but basic question (sometimes seen on other sites in the network), mistranslation (but the Q reads like it was written by a native speaker), or a pilot who somehow qualified without knowing much about aerodynamics. The reader can draw their own conclusion as to which one applies (@Kittoes0124)
$endgroup$
– Chris H
12 hours ago
$begingroup$
As someone who only has a little reading and no practical training on the subject I knew the answer from the title. A novice may not, but then you get to the word "airline" and a description of regular practice. That suggests a few possibilities: Trolling, story-telling in the name of an instructive but basic question (sometimes seen on other sites in the network), mistranslation (but the Q reads like it was written by a native speaker), or a pilot who somehow qualified without knowing much about aerodynamics. The reader can draw their own conclusion as to which one applies (@Kittoes0124)
$endgroup$
– Chris H
12 hours ago
12
12
$begingroup$
@Kittoes0124 Day 1 of somebody's flying training isn't compatible with "the procedure in my airline." There's nothing at all wrong with asking basic questions but asking basic questions while claiming to be a professional in a safety-critical job is something completely different. If the asker is in the position they claim to be in, they should have known the answer to this question long ago. Random member of the public asks why surgeons wash their hands? Fine. Somebody says "I took a shower this morning but, in my hospital, procedure is we should wash our hands before surgery -- why?" Problem
$endgroup$
– David Richerby
11 hours ago
$begingroup$
@Kittoes0124 Day 1 of somebody's flying training isn't compatible with "the procedure in my airline." There's nothing at all wrong with asking basic questions but asking basic questions while claiming to be a professional in a safety-critical job is something completely different. If the asker is in the position they claim to be in, they should have known the answer to this question long ago. Random member of the public asks why surgeons wash their hands? Fine. Somebody says "I took a shower this morning but, in my hospital, procedure is we should wash our hands before surgery -- why?" Problem
$endgroup$
– David Richerby
11 hours ago
8
8
$begingroup$
@Kittoes0124 There's enough information (THR HOLD @ 80kts) to guess that OP is training in some type of Boeing passenger jet, likely a 737. Mike's comment does not express negativity, only justifiable disbelief that someone could be at the yoke of such an aircraft, in training or otherwise, without knowing which speed indicator to look at (or why!) during critical phases of flight. Even a student at this level should be able to answer this question without effort or hesitation. The only thing expressed here is scepticism that this is an honest question.
$endgroup$
– J...
10 hours ago
$begingroup$
@Kittoes0124 There's enough information (THR HOLD @ 80kts) to guess that OP is training in some type of Boeing passenger jet, likely a 737. Mike's comment does not express negativity, only justifiable disbelief that someone could be at the yoke of such an aircraft, in training or otherwise, without knowing which speed indicator to look at (or why!) during critical phases of flight. Even a student at this level should be able to answer this question without effort or hesitation. The only thing expressed here is scepticism that this is an honest question.
$endgroup$
– J...
10 hours ago
|
show 19 more comments
4 Answers
4
active
oldest
votes
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Because wings work on air moving past them, not ground moving below them.
Heck, in a 35 knot headwind, the Antonov-2 could be rolling backwards at 2 knots and still take off!
answered yesterday
HarperHarper
3,631721
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1
$begingroup$
This is already explained in the existing answers. Why add one more?
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– Mast
yesterday
20
$begingroup$
@mast My explanation is far simpler. Which seems to be warranted here.
$endgroup$
– Harper
yesterday
1
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Agreed, this is why carriers head into the wind. More than one aircraft landed with negative ground speed during WW1.
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– mckenzm
yesterday
3
$begingroup$
Other answers are based on the same ideas, but this one puts it most directly.
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– David K
23 hours ago
1
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Sometimes the best answers are also the simplest.
$endgroup$
– brhans
2 hours ago
add a comment |
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Because what determines the amount of lift generated is the indicated airspeed, not the ground speed. As usual, it is always easier to think about an extreme case. If you have an aircraft with VR (speed at rotation for takeoff) of 90 knots, and there is an 80 knots head wind, in theory it will rotate with ground speed of 10 knots even though the indicated airspeed will be 90 knots.
edited yesterday
StephenS
4,1711725
answered yesterday
DeepSpaceDeepSpace
1,605713
$endgroup$
9
$begingroup$
@Notts90 True, but it seems like OP is a pilot or studying to become one. Let's hope they know what Vr is
$endgroup$
– DeepSpace
yesterday
2
$begingroup$
My guess is airline-sponsored primary training. I'd hope he knows what Vr is by now, but I'm not sure we can assume it was explained correctly if he's asking this question.
$endgroup$
– StephenS
yesterday
10
$begingroup$
I don't remember offhand what every V speed means, and this site isn't exclusively for pilots anyway, so why not tell everyone what Vr is? Save some google searches.
$endgroup$
– Xen2050
yesterday
5
$begingroup$
For those interested: Vr is defined as the speed at which the rotation of the aircraft should be initiated to takeoff attitude.
$endgroup$
– Mast
yesterday
6
$begingroup$
@DeepSpace While OP may be training to be a pilot, let's try to remember that SE is for everyone, and is likely to involve others viewing this question later who may not be training as a pilot. For that reason it's usually worth avoiding jargon or adding a quick explanation
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– Jon Story
yesterday
|
show 5 more comments
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Airspeed is always important as it determines lift which keeps you in the air. At the moment of takeoff or landing, airspeed is critical because it is the point at which you transition to or from flight; you need to be going fast enough but not too fast so that the transition is positive without being abrupt or overly stressful on aircraft components.
Ground speed matters in navigation because it determines flight time which affects fuel required to get from A to B.
answered yesterday
Anthony XAnthony X
1,8791116
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+1 for mentioning why both are important
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– MPW
14 hours ago
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It should be noted that groundspeed is also important during takeoff... if you're rejecting the takeoff.
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– Sean
1 hour ago
add a comment |
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The IAS includes factors such as Wind Component (Tail, Head or Cross), Pressure and Temperature. All these have an influence on your takeoff. The takeoff Speed Vr is calculated as Indicated Airspeed. Imagine you have a Headwind Component of +50. You Groundspeed would be way lower than your Airspeed. What counts is the amount of air that flows over the wing in order to takeoff, not the speed relative to the ground.
answered yesterday
WindshearWindshear
1313
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Windshear is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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add a comment |
protected by Federico♦ 11 hours ago
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Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).
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4 Answers
4
active
oldest
votes
4 Answers
4
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
Because wings work on air moving past them, not ground moving below them.
Heck, in a 35 knot headwind, the Antonov-2 could be rolling backwards at 2 knots and still take off!
answered yesterday
HarperHarper
3,631721
$endgroup$
1
$begingroup$
This is already explained in the existing answers. Why add one more?
$endgroup$
– Mast
yesterday
20
$begingroup$
@mast My explanation is far simpler. Which seems to be warranted here.
$endgroup$
– Harper
yesterday
1
$begingroup$
Agreed, this is why carriers head into the wind. More than one aircraft landed with negative ground speed during WW1.
$endgroup$
– mckenzm
yesterday
3
$begingroup$
Other answers are based on the same ideas, but this one puts it most directly.
$endgroup$
– David K
23 hours ago
1
$begingroup$
Sometimes the best answers are also the simplest.
$endgroup$
– brhans
2 hours ago
add a comment |
$begingroup$
Because wings work on air moving past them, not ground moving below them.
Heck, in a 35 knot headwind, the Antonov-2 could be rolling backwards at 2 knots and still take off!
answered yesterday
HarperHarper
3,631721
$endgroup$
1
$begingroup$
This is already explained in the existing answers. Why add one more?
$endgroup$
– Mast
yesterday
20
$begingroup$
@mast My explanation is far simpler. Which seems to be warranted here.
$endgroup$
– Harper
yesterday
1
$begingroup$
Agreed, this is why carriers head into the wind. More than one aircraft landed with negative ground speed during WW1.
$endgroup$
– mckenzm
yesterday
3
$begingroup$
Other answers are based on the same ideas, but this one puts it most directly.
$endgroup$
– David K
23 hours ago
1
$begingroup$
Sometimes the best answers are also the simplest.
$endgroup$
– brhans
2 hours ago
add a comment |
$begingroup$
Because wings work on air moving past them, not ground moving below them.
Heck, in a 35 knot headwind, the Antonov-2 could be rolling backwards at 2 knots and still take off!
answered yesterday
HarperHarper
3,631721
$endgroup$
Because wings work on air moving past them, not ground moving below them.
Heck, in a 35 knot headwind, the Antonov-2 could be rolling backwards at 2 knots and still take off!
answered yesterday
HarperHarper
3,631721
edited yesterday
answered yesterday
HarperHarper
3,631721
answered yesterday
HarperHarper
3,631721
answered yesterday
HarperHarper
3,631721
3,631721
1
$begingroup$
This is already explained in the existing answers. Why add one more?
$endgroup$
– Mast
yesterday
20
$begingroup$
@mast My explanation is far simpler. Which seems to be warranted here.
$endgroup$
– Harper
yesterday
1
$begingroup$
Agreed, this is why carriers head into the wind. More than one aircraft landed with negative ground speed during WW1.
$endgroup$
– mckenzm
yesterday
3
$begingroup$
Other answers are based on the same ideas, but this one puts it most directly.
$endgroup$
– David K
23 hours ago
1
$begingroup$
Sometimes the best answers are also the simplest.
$endgroup$
– brhans
2 hours ago
add a comment |
1
$begingroup$
This is already explained in the existing answers. Why add one more?
$endgroup$
– Mast
yesterday
20
$begingroup$
@mast My explanation is far simpler. Which seems to be warranted here.
$endgroup$
– Harper
yesterday
1
$begingroup$
Agreed, this is why carriers head into the wind. More than one aircraft landed with negative ground speed during WW1.
$endgroup$
– mckenzm
yesterday
3
$begingroup$
Other answers are based on the same ideas, but this one puts it most directly.
$endgroup$
– David K
23 hours ago
1
$begingroup$
Sometimes the best answers are also the simplest.
$endgroup$
– brhans
2 hours ago
1
1
$begingroup$
This is already explained in the existing answers. Why add one more?
$endgroup$
– Mast
yesterday
$begingroup$
This is already explained in the existing answers. Why add one more?
$endgroup$
– Mast
yesterday
20
20
$begingroup$
@mast My explanation is far simpler. Which seems to be warranted here.
$endgroup$
– Harper
yesterday
$begingroup$
@mast My explanation is far simpler. Which seems to be warranted here.
$endgroup$
– Harper
yesterday
1
1
$begingroup$
Agreed, this is why carriers head into the wind. More than one aircraft landed with negative ground speed during WW1.
$endgroup$
– mckenzm
yesterday
$begingroup$
Agreed, this is why carriers head into the wind. More than one aircraft landed with negative ground speed during WW1.
$endgroup$
– mckenzm
yesterday
3
3
$begingroup$
Other answers are based on the same ideas, but this one puts it most directly.
$endgroup$
– David K
23 hours ago
$begingroup$
Other answers are based on the same ideas, but this one puts it most directly.
$endgroup$
– David K
23 hours ago
1
1
$begingroup$
Sometimes the best answers are also the simplest.
$endgroup$
– brhans
2 hours ago
$begingroup$
Sometimes the best answers are also the simplest.
$endgroup$
– brhans
2 hours ago
add a comment |
$begingroup$
Because what determines the amount of lift generated is the indicated airspeed, not the ground speed. As usual, it is always easier to think about an extreme case. If you have an aircraft with VR (speed at rotation for takeoff) of 90 knots, and there is an 80 knots head wind, in theory it will rotate with ground speed of 10 knots even though the indicated airspeed will be 90 knots.
edited yesterday
StephenS
4,1711725
answered yesterday
DeepSpaceDeepSpace
1,605713
$endgroup$
9
$begingroup$
@Notts90 True, but it seems like OP is a pilot or studying to become one. Let's hope they know what Vr is
$endgroup$
– DeepSpace
yesterday
2
$begingroup$
My guess is airline-sponsored primary training. I'd hope he knows what Vr is by now, but I'm not sure we can assume it was explained correctly if he's asking this question.
$endgroup$
– StephenS
yesterday
10
$begingroup$
I don't remember offhand what every V speed means, and this site isn't exclusively for pilots anyway, so why not tell everyone what Vr is? Save some google searches.
$endgroup$
– Xen2050
yesterday
5
$begingroup$
For those interested: Vr is defined as the speed at which the rotation of the aircraft should be initiated to takeoff attitude.
$endgroup$
– Mast
yesterday
6
$begingroup$
@DeepSpace While OP may be training to be a pilot, let's try to remember that SE is for everyone, and is likely to involve others viewing this question later who may not be training as a pilot. For that reason it's usually worth avoiding jargon or adding a quick explanation
$endgroup$
– Jon Story
yesterday
|
show 5 more comments
$begingroup$
Because what determines the amount of lift generated is the indicated airspeed, not the ground speed. As usual, it is always easier to think about an extreme case. If you have an aircraft with VR (speed at rotation for takeoff) of 90 knots, and there is an 80 knots head wind, in theory it will rotate with ground speed of 10 knots even though the indicated airspeed will be 90 knots.
edited yesterday
StephenS
4,1711725
answered yesterday
DeepSpaceDeepSpace
1,605713
$endgroup$
9
$begingroup$
@Notts90 True, but it seems like OP is a pilot or studying to become one. Let's hope they know what Vr is
$endgroup$
– DeepSpace
yesterday
2
$begingroup$
My guess is airline-sponsored primary training. I'd hope he knows what Vr is by now, but I'm not sure we can assume it was explained correctly if he's asking this question.
$endgroup$
– StephenS
yesterday
10
$begingroup$
I don't remember offhand what every V speed means, and this site isn't exclusively for pilots anyway, so why not tell everyone what Vr is? Save some google searches.
$endgroup$
– Xen2050
yesterday
5
$begingroup$
For those interested: Vr is defined as the speed at which the rotation of the aircraft should be initiated to takeoff attitude.
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– Mast
yesterday
6
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@DeepSpace While OP may be training to be a pilot, let's try to remember that SE is for everyone, and is likely to involve others viewing this question later who may not be training as a pilot. For that reason it's usually worth avoiding jargon or adding a quick explanation
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– Jon Story
yesterday
|
show 5 more comments
$begingroup$
Because what determines the amount of lift generated is the indicated airspeed, not the ground speed. As usual, it is always easier to think about an extreme case. If you have an aircraft with VR (speed at rotation for takeoff) of 90 knots, and there is an 80 knots head wind, in theory it will rotate with ground speed of 10 knots even though the indicated airspeed will be 90 knots.
edited yesterday
StephenS
4,1711725
answered yesterday
DeepSpaceDeepSpace
1,605713
$endgroup$
Because what determines the amount of lift generated is the indicated airspeed, not the ground speed. As usual, it is always easier to think about an extreme case. If you have an aircraft with VR (speed at rotation for takeoff) of 90 knots, and there is an 80 knots head wind, in theory it will rotate with ground speed of 10 knots even though the indicated airspeed will be 90 knots.
edited yesterday
StephenS
4,1711725
answered yesterday
DeepSpaceDeepSpace
1,605713
edited yesterday
StephenS
4,1711725
edited yesterday
StephenS
4,1711725
edited yesterday
StephenS
4,1711725
4,1711725
answered yesterday
DeepSpaceDeepSpace
1,605713
answered yesterday
DeepSpaceDeepSpace
1,605713
answered yesterday
DeepSpaceDeepSpace
1,605713
1,605713
9
$begingroup$
@Notts90 True, but it seems like OP is a pilot or studying to become one. Let's hope they know what Vr is
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– DeepSpace
yesterday
2
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My guess is airline-sponsored primary training. I'd hope he knows what Vr is by now, but I'm not sure we can assume it was explained correctly if he's asking this question.
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– StephenS
yesterday
10
$begingroup$
I don't remember offhand what every V speed means, and this site isn't exclusively for pilots anyway, so why not tell everyone what Vr is? Save some google searches.
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– Xen2050
yesterday
5
$begingroup$
For those interested: Vr is defined as the speed at which the rotation of the aircraft should be initiated to takeoff attitude.
$endgroup$
– Mast
yesterday
6
$begingroup$
@DeepSpace While OP may be training to be a pilot, let's try to remember that SE is for everyone, and is likely to involve others viewing this question later who may not be training as a pilot. For that reason it's usually worth avoiding jargon or adding a quick explanation
$endgroup$
– Jon Story
yesterday
|
show 5 more comments
9
$begingroup$
@Notts90 True, but it seems like OP is a pilot or studying to become one. Let's hope they know what Vr is
$endgroup$
– DeepSpace
yesterday
2
$begingroup$
My guess is airline-sponsored primary training. I'd hope he knows what Vr is by now, but I'm not sure we can assume it was explained correctly if he's asking this question.
$endgroup$
– StephenS
yesterday
10
$begingroup$
I don't remember offhand what every V speed means, and this site isn't exclusively for pilots anyway, so why not tell everyone what Vr is? Save some google searches.
$endgroup$
– Xen2050
yesterday
5
$begingroup$
For those interested: Vr is defined as the speed at which the rotation of the aircraft should be initiated to takeoff attitude.
$endgroup$
– Mast
yesterday
6
$begingroup$
@DeepSpace While OP may be training to be a pilot, let's try to remember that SE is for everyone, and is likely to involve others viewing this question later who may not be training as a pilot. For that reason it's usually worth avoiding jargon or adding a quick explanation
$endgroup$
– Jon Story
yesterday
9
9
$begingroup$
@Notts90 True, but it seems like OP is a pilot or studying to become one. Let's hope they know what Vr is
$endgroup$
– DeepSpace
yesterday
$begingroup$
@Notts90 True, but it seems like OP is a pilot or studying to become one. Let's hope they know what Vr is
$endgroup$
– DeepSpace
yesterday
2
2
$begingroup$
My guess is airline-sponsored primary training. I'd hope he knows what Vr is by now, but I'm not sure we can assume it was explained correctly if he's asking this question.
$endgroup$
– StephenS
yesterday
$begingroup$
My guess is airline-sponsored primary training. I'd hope he knows what Vr is by now, but I'm not sure we can assume it was explained correctly if he's asking this question.
$endgroup$
– StephenS
yesterday
10
10
$begingroup$
I don't remember offhand what every V speed means, and this site isn't exclusively for pilots anyway, so why not tell everyone what Vr is? Save some google searches.
$endgroup$
– Xen2050
yesterday
$begingroup$
I don't remember offhand what every V speed means, and this site isn't exclusively for pilots anyway, so why not tell everyone what Vr is? Save some google searches.
$endgroup$
– Xen2050
yesterday
5
5
$begingroup$
For those interested: Vr is defined as the speed at which the rotation of the aircraft should be initiated to takeoff attitude.
$endgroup$
– Mast
yesterday
$begingroup$
For those interested: Vr is defined as the speed at which the rotation of the aircraft should be initiated to takeoff attitude.
$endgroup$
– Mast
yesterday
6
6
$begingroup$
@DeepSpace While OP may be training to be a pilot, let's try to remember that SE is for everyone, and is likely to involve others viewing this question later who may not be training as a pilot. For that reason it's usually worth avoiding jargon or adding a quick explanation
$endgroup$
– Jon Story
yesterday
$begingroup$
@DeepSpace While OP may be training to be a pilot, let's try to remember that SE is for everyone, and is likely to involve others viewing this question later who may not be training as a pilot. For that reason it's usually worth avoiding jargon or adding a quick explanation
$endgroup$
– Jon Story
yesterday
|
show 5 more comments
$begingroup$
Airspeed is always important as it determines lift which keeps you in the air. At the moment of takeoff or landing, airspeed is critical because it is the point at which you transition to or from flight; you need to be going fast enough but not too fast so that the transition is positive without being abrupt or overly stressful on aircraft components.
Ground speed matters in navigation because it determines flight time which affects fuel required to get from A to B.
answered yesterday
Anthony XAnthony X
1,8791116
$endgroup$
$begingroup$
+1 for mentioning why both are important
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– MPW
14 hours ago
$begingroup$
It should be noted that groundspeed is also important during takeoff... if you're rejecting the takeoff.
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– Sean
1 hour ago
add a comment |
$begingroup$
Airspeed is always important as it determines lift which keeps you in the air. At the moment of takeoff or landing, airspeed is critical because it is the point at which you transition to or from flight; you need to be going fast enough but not too fast so that the transition is positive without being abrupt or overly stressful on aircraft components.
Ground speed matters in navigation because it determines flight time which affects fuel required to get from A to B.
answered yesterday
Anthony XAnthony X
1,8791116
$endgroup$
$begingroup$
+1 for mentioning why both are important
$endgroup$
– MPW
14 hours ago
$begingroup$
It should be noted that groundspeed is also important during takeoff... if you're rejecting the takeoff.
$endgroup$
– Sean
1 hour ago
add a comment |
$begingroup$
Airspeed is always important as it determines lift which keeps you in the air. At the moment of takeoff or landing, airspeed is critical because it is the point at which you transition to or from flight; you need to be going fast enough but not too fast so that the transition is positive without being abrupt or overly stressful on aircraft components.
Ground speed matters in navigation because it determines flight time which affects fuel required to get from A to B.
answered yesterday
Anthony XAnthony X
1,8791116
$endgroup$
Airspeed is always important as it determines lift which keeps you in the air. At the moment of takeoff or landing, airspeed is critical because it is the point at which you transition to or from flight; you need to be going fast enough but not too fast so that the transition is positive without being abrupt or overly stressful on aircraft components.
Ground speed matters in navigation because it determines flight time which affects fuel required to get from A to B.
answered yesterday
Anthony XAnthony X
1,8791116
answered yesterday
Anthony XAnthony X
1,8791116
answered yesterday
Anthony XAnthony X
1,8791116
answered yesterday
Anthony XAnthony X
1,8791116
1,8791116
$begingroup$
+1 for mentioning why both are important
$endgroup$
– MPW
14 hours ago
$begingroup$
It should be noted that groundspeed is also important during takeoff... if you're rejecting the takeoff.
$endgroup$
– Sean
1 hour ago
add a comment |
$begingroup$
+1 for mentioning why both are important
$endgroup$
– MPW
14 hours ago
$begingroup$
It should be noted that groundspeed is also important during takeoff... if you're rejecting the takeoff.
$endgroup$
– Sean
1 hour ago
$begingroup$
+1 for mentioning why both are important
$endgroup$
– MPW
14 hours ago
$begingroup$
+1 for mentioning why both are important
$endgroup$
– MPW
14 hours ago
$begingroup$
It should be noted that groundspeed is also important during takeoff... if you're rejecting the takeoff.
$endgroup$
– Sean
1 hour ago
$begingroup$
It should be noted that groundspeed is also important during takeoff... if you're rejecting the takeoff.
$endgroup$
– Sean
1 hour ago
add a comment |
$begingroup$
The IAS includes factors such as Wind Component (Tail, Head or Cross), Pressure and Temperature. All these have an influence on your takeoff. The takeoff Speed Vr is calculated as Indicated Airspeed. Imagine you have a Headwind Component of +50. You Groundspeed would be way lower than your Airspeed. What counts is the amount of air that flows over the wing in order to takeoff, not the speed relative to the ground.
answered yesterday
WindshearWindshear
1313
New contributor
Windshear is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
The IAS includes factors such as Wind Component (Tail, Head or Cross), Pressure and Temperature. All these have an influence on your takeoff. The takeoff Speed Vr is calculated as Indicated Airspeed. Imagine you have a Headwind Component of +50. You Groundspeed would be way lower than your Airspeed. What counts is the amount of air that flows over the wing in order to takeoff, not the speed relative to the ground.
answered yesterday
WindshearWindshear
1313
New contributor
Windshear is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
add a comment |
$begingroup$
The IAS includes factors such as Wind Component (Tail, Head or Cross), Pressure and Temperature. All these have an influence on your takeoff. The takeoff Speed Vr is calculated as Indicated Airspeed. Imagine you have a Headwind Component of +50. You Groundspeed would be way lower than your Airspeed. What counts is the amount of air that flows over the wing in order to takeoff, not the speed relative to the ground.
answered yesterday
WindshearWindshear
1313
New contributor
Windshear is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
$endgroup$
The IAS includes factors such as Wind Component (Tail, Head or Cross), Pressure and Temperature. All these have an influence on your takeoff. The takeoff Speed Vr is calculated as Indicated Airspeed. Imagine you have a Headwind Component of +50. You Groundspeed would be way lower than your Airspeed. What counts is the amount of air that flows over the wing in order to takeoff, not the speed relative to the ground.
answered yesterday
WindshearWindshear
1313
New contributor
Windshear is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered yesterday
WindshearWindshear
1313
New contributor
Windshear is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
answered yesterday
WindshearWindshear
1313
answered yesterday
WindshearWindshear
1313
1313
New contributor
Windshear is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
New contributor
Windshear is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
Windshear is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.
add a comment |
add a comment |
protected by Federico♦ 11 hours ago
Thank you for your interest in this question.
Because it has attracted low-quality or spam answers that had to be removed, posting an answer now requires 10 reputation on this site (the association bonus does not count).
Would you like to answer one of these unanswered questions instead?
57
$begingroup$
It seems you are a commercial pilot working at an airline and being trained on a new aircraft type. If that is true, I find it hard to believe that you don't understand the difference between indicated airspeed and ground speed.
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– Mike Sowsun
yesterday
9
$begingroup$
@Kittoes0124 The point is valid. I think anyone involved with aircraft would find it unsettling to see someone training at this level of professional aviation who could not answer this extremely basic question. The only logical conclusion is that either OP is the one trolling HNQ with a sensational question OR they represent a serious danger to the flying public and, hopefully, received a clear and unapologetic failing grade from their instructor.
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– J...
13 hours ago
10
$begingroup$
As someone who only has a little reading and no practical training on the subject I knew the answer from the title. A novice may not, but then you get to the word "airline" and a description of regular practice. That suggests a few possibilities: Trolling, story-telling in the name of an instructive but basic question (sometimes seen on other sites in the network), mistranslation (but the Q reads like it was written by a native speaker), or a pilot who somehow qualified without knowing much about aerodynamics. The reader can draw their own conclusion as to which one applies (@Kittoes0124)
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– Chris H
12 hours ago
12
$begingroup$
@Kittoes0124 Day 1 of somebody's flying training isn't compatible with "the procedure in my airline." There's nothing at all wrong with asking basic questions but asking basic questions while claiming to be a professional in a safety-critical job is something completely different. If the asker is in the position they claim to be in, they should have known the answer to this question long ago. Random member of the public asks why surgeons wash their hands? Fine. Somebody says "I took a shower this morning but, in my hospital, procedure is we should wash our hands before surgery -- why?" Problem
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– David Richerby
11 hours ago
8
$begingroup$
@Kittoes0124 There's enough information (THR HOLD @ 80kts) to guess that OP is training in some type of Boeing passenger jet, likely a 737. Mike's comment does not express negativity, only justifiable disbelief that someone could be at the yoke of such an aircraft, in training or otherwise, without knowing which speed indicator to look at (or why!) during critical phases of flight. Even a student at this level should be able to answer this question without effort or hesitation. The only thing expressed here is scepticism that this is an honest question.
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– J...
10 hours ago