When to descend while on a visual approach...?
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When to descend while on a visual approach...?
Hello everyone. I'm new to this forum, so please excuse any mistakes or non-compliances.
I am not a professional pilot, but am very interested in aviation. I am a simmer and I sim a lot on MS FS2004. My dilemma while flying on MSFS is 'when to descend'... In any case, I always wanted to know when a pilot decides to descend while on a visual approach.
Supposing, eg, you are cleared for a visual approach to a runway at 2000 ft, when do you start your descent and at what rate? I know MSFS has its limitations, but I would appreciate if a professional pilot can answer my question.
Do you manually make the aircraft descend using the control yoke/sidestick or do you set a minimum altitude and then a rate of descent on the V/S? I know that the rate of descent must not exceed 1000 fpm, it should be around 600-800 fpm...
I am not a professional pilot, but am very interested in aviation. I am a simmer and I sim a lot on MS FS2004. My dilemma while flying on MSFS is 'when to descend'... In any case, I always wanted to know when a pilot decides to descend while on a visual approach.
Supposing, eg, you are cleared for a visual approach to a runway at 2000 ft, when do you start your descent and at what rate? I know MSFS has its limitations, but I would appreciate if a professional pilot can answer my question.
Do you manually make the aircraft descend using the control yoke/sidestick or do you set a minimum altitude and then a rate of descent on the V/S? I know that the rate of descent must not exceed 1000 fpm, it should be around 600-800 fpm...
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start from 3,500ft (generally always 1,500ft above aerodrome level, terrain permitting).
When going downwind. 20 seconds after passing the throshold of the landing runway select gear down and intermediate flap. 45 seconds after passing the throshold runway start your turn onto final approach. As you pass throgh 45 degrees (of the 180 degree) of turn required to line up with the runway, you should become visual with the runway. At this point start a gentle 300-400fpm rate of descent and select landing flap. When fully configured with landing flap go down at a rate that is half your groundspeed. So for example if you ar 160 knots go down at 800FPM. If you are 140 knots go down at 700fpm.
When going downwind. 20 seconds after passing the throshold of the landing runway select gear down and intermediate flap. 45 seconds after passing the throshold runway start your turn onto final approach. As you pass throgh 45 degrees (of the 180 degree) of turn required to line up with the runway, you should become visual with the runway. At this point start a gentle 300-400fpm rate of descent and select landing flap. When fully configured with landing flap go down at a rate that is half your groundspeed. So for example if you ar 160 knots go down at 800FPM. If you are 140 knots go down at 700fpm.
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It all depends............
Light aircooled piston aircraft, singles or twins, need careful handlinling if you want to preserve engine life. Going from cruise power (or even worse) climb power to idle without giving the engine a chance to cool properley will result in cracked cylinder heads. Liquid cooled engines don't have the same problems.
Thje descent technique is to work out a power setting that will give you a modest rate of descent, and keep the engine warm. Normally this will be under 1000 feet per minute. Therefore work out how much TIME you need to descend either to circuit or platform height and go down accordingly.
Turbine powered aircraft are a different matter. Flight idle is available and can be used as required. Your limitations tend to be passenger comfort. Either rate of descent in un pressurised aircaft (eg Shorts 360, Cessna Caravan etc) or body angle for draggy jets (eg F100) or accelerating through Vmo or Mmo for slippery jets (most of them).
Thrust idle will give between 1500 and 3000 fpm, depending on weight, altitude and temperature. If we let the aircraft accelerate then 6000 fpm is possible for short periods.
We don't normally fly circuits so we tend to allow 3 nm per thousand feet, plus 1 nm for each 10 kts to loose. eg from 35000 and 270 kts indicated, you need 35 x 3 plus 27 - 18 gives 105 + 9 is about 124 miles out if you want to be stable at 180 kts on the approach. Head or tail winds need factoring by about 1 nm per 10 kts.
All very rough, but it'll put you in the right area for almost any aircraft type.
Light aircooled piston aircraft, singles or twins, need careful handlinling if you want to preserve engine life. Going from cruise power (or even worse) climb power to idle without giving the engine a chance to cool properley will result in cracked cylinder heads. Liquid cooled engines don't have the same problems.
Thje descent technique is to work out a power setting that will give you a modest rate of descent, and keep the engine warm. Normally this will be under 1000 feet per minute. Therefore work out how much TIME you need to descend either to circuit or platform height and go down accordingly.
Turbine powered aircraft are a different matter. Flight idle is available and can be used as required. Your limitations tend to be passenger comfort. Either rate of descent in un pressurised aircaft (eg Shorts 360, Cessna Caravan etc) or body angle for draggy jets (eg F100) or accelerating through Vmo or Mmo for slippery jets (most of them).
Thrust idle will give between 1500 and 3000 fpm, depending on weight, altitude and temperature. If we let the aircraft accelerate then 6000 fpm is possible for short periods.
We don't normally fly circuits so we tend to allow 3 nm per thousand feet, plus 1 nm for each 10 kts to loose. eg from 35000 and 270 kts indicated, you need 35 x 3 plus 27 - 18 gives 105 + 9 is about 124 miles out if you want to be stable at 180 kts on the approach. Head or tail winds need factoring by about 1 nm per 10 kts.
All very rough, but it'll put you in the right area for almost any aircraft type.
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Nubboy's right, I'll just add these rules of thumb.
- Height should be 1/3 of distance to touchdown (at 12 miles, you want to be at 4000' (ish)
- Rate of descent should be 5 * ground speed. So at 100kts, you need 500 ft / min
Nubboy's point about slowing down is very important too! The numbers I've just given are for if you're already slowed and configured. If you're coming down from very high (we go up to FL510) I use the same numbers and add 10NM to slow down.
- Height should be 1/3 of distance to touchdown (at 12 miles, you want to be at 4000' (ish)
- Rate of descent should be 5 * ground speed. So at 100kts, you need 500 ft / min
Nubboy's point about slowing down is very important too! The numbers I've just given are for if you're already slowed and configured. If you're coming down from very high (we go up to FL510) I use the same numbers and add 10NM to slow down.
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Thanks to all for replying. I should have been more specific while asking my question about which aircraft I'm flying and the flight rules, also I was referring to the final approach phase and a straight-in approach.
As I said, I'm not a pro, so all that computation as suggested by Nubboy is a little bit complicated for me.
"Rate of descent should be 5 * ground speed. So at 100kts, you need 500 ft / min" - I'll keep that in mind.
I'm currently flying the A320, so all my flights are IFR. To get an idea of what I should do on a visual approach, what I would do is, observe the rate of descent while flying an ILS approach, which is usually about 600 fpm. I've seen that the aircraft starts descending approximately 6-7 miles from touchdown after intercepting the glideslope. What I do on a visual approach is, when I am 6-7 miles from touchdown, I switch off the autopilot and then put the aircraft into a descent manually with flaps at 3 and landing gear down with speed at VAPP (as computed by the FMGC), then at 1,000 ft radio altitude, I select full flaps and make adjustments to line up with the runway. I've been able to land successfully on several occasions, but I sometimes have difficulty controlling the speed. I've come to realise, that I'm probably too fast when I'm cleared for the approach, the approach then becomes unstable and I have to abort and go-around.
I'm somehow not able to accomplish a smooth touchdown while flying manually. Do pilots encounter such a problem in real life too?
Also, there is a bit of confusion in my mind about the difference between VAPP and VREF. Since VREF is the 'approach reference speed' and VAPP is the 'target approach speed', do I maintain VAPP or VREF on final approach? Do I have to achieve VREF on short finals or when stabilising the aircraft at 1,000 ft as required on an ILS approach? Do I touchdown at VAPP or VREF? The FMGC on the A320 only gives two speeds VAPP and VLS (minimum selectable speed).
As I said, I'm not a pro, so all that computation as suggested by Nubboy is a little bit complicated for me.
"Rate of descent should be 5 * ground speed. So at 100kts, you need 500 ft / min" - I'll keep that in mind.
I'm currently flying the A320, so all my flights are IFR. To get an idea of what I should do on a visual approach, what I would do is, observe the rate of descent while flying an ILS approach, which is usually about 600 fpm. I've seen that the aircraft starts descending approximately 6-7 miles from touchdown after intercepting the glideslope. What I do on a visual approach is, when I am 6-7 miles from touchdown, I switch off the autopilot and then put the aircraft into a descent manually with flaps at 3 and landing gear down with speed at VAPP (as computed by the FMGC), then at 1,000 ft radio altitude, I select full flaps and make adjustments to line up with the runway. I've been able to land successfully on several occasions, but I sometimes have difficulty controlling the speed. I've come to realise, that I'm probably too fast when I'm cleared for the approach, the approach then becomes unstable and I have to abort and go-around.
I'm somehow not able to accomplish a smooth touchdown while flying manually. Do pilots encounter such a problem in real life too?
Also, there is a bit of confusion in my mind about the difference between VAPP and VREF. Since VREF is the 'approach reference speed' and VAPP is the 'target approach speed', do I maintain VAPP or VREF on final approach? Do I have to achieve VREF on short finals or when stabilising the aircraft at 1,000 ft as required on an ILS approach? Do I touchdown at VAPP or VREF? The FMGC on the A320 only gives two speeds VAPP and VLS (minimum selectable speed).
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I'm not familiar with what's known as "airboos logique" so I don't know the strict definition of Vapp and Vls, however I do know what Vref is as it's a universal term. Here's my definitions (not gospel)
Vref: 1.3 * stall speed. This is the absolute minimum speed for the approach.
Vapp: Vref + a bit extra, e.g. for gusty winds or if there's a potential for windshear. This adds an extra margin.
Vls: Lowest selectable speed. The automatics won't allow you to select a lower speed.
The approach technique you're using is a bit advanced for someone without much training. I'd suggest getting it all configured before intercepting the glideslope (at 2-3000 feet). Configuration changes at 1000 feet will destabilize the aircraft at the last minute and not give you much time to fix it.
As for the landing... again, I'm not a bus driver but the technique is pretty much the same for all large aircraft.
50 ft: close throttles
30 ft: wait a second
20 ft: raise the nose a couple of degrees
hold it there. Don't try to land the plane. You're just arresting the rate of descent. As it slows down you'll gently sink onto the runway.
10 ft: squeeze (don't kick) off the drift with the rudder
squeek go the tyres
remember the nose is still flying. Put it down gently.
Vref: 1.3 * stall speed. This is the absolute minimum speed for the approach.
Vapp: Vref + a bit extra, e.g. for gusty winds or if there's a potential for windshear. This adds an extra margin.
Vls: Lowest selectable speed. The automatics won't allow you to select a lower speed.
The approach technique you're using is a bit advanced for someone without much training. I'd suggest getting it all configured before intercepting the glideslope (at 2-3000 feet). Configuration changes at 1000 feet will destabilize the aircraft at the last minute and not give you much time to fix it.
As for the landing... again, I'm not a bus driver but the technique is pretty much the same for all large aircraft.
50 ft: close throttles
30 ft: wait a second
20 ft: raise the nose a couple of degrees
hold it there. Don't try to land the plane. You're just arresting the rate of descent. As it slows down you'll gently sink onto the runway.
10 ft: squeeze (don't kick) off the drift with the rudder
squeek go the tyres
remember the nose is still flying. Put it down gently.
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The FMGC that I use on my A320 does allow VLS to be selected. I read a thread on this form (http://www.pprune.org/archive/index.php/t-165372.html) which says the following: "The VLS is the slowest speed the Airbus lets you fly. The automatics in the normal life prevent flying below this speed, but you still can dial in a lower speed than that on the FCU." 
The aircraft must be stabilised by 500 ft when on a visual approach, but I find it difficult to do so (sometimes). I make my adjustments to line up with the runway well before 500 ft or even 1,000 ft (depending on which altitude I've been cleared for the approach - usually between 4,000 and 2,000 ft AGL and between 6/7 miles to 15/20 miles from touchdown).
You say: "The approach technique you're using is a bit advanced for someone without much training." What exactly do you mean by that? Am I going in the right direction?
This might seem wierd but, when I try to flare the aircraft manually after closing the throttles at 20 ft, the aircraft begins to climb away from the runway rather than settling down!
I then have to go-around only if I don't stall in the meantime and crash.
I have some trouble controlling the aircraft during a crosswind, because I only have a joystick and no rudder pedals for yaw control in MSFS
and it is very inconvenient to use keys to control the rudder. What I've done now is adjusted the joystick so that it gives me both roll and yaw. The aircraft handles better now.
The aircraft must be stabilised by 500 ft when on a visual approach, but I find it difficult to do so (sometimes). I make my adjustments to line up with the runway well before 500 ft or even 1,000 ft (depending on which altitude I've been cleared for the approach - usually between 4,000 and 2,000 ft AGL and between 6/7 miles to 15/20 miles from touchdown).
You say: "The approach technique you're using is a bit advanced for someone without much training." What exactly do you mean by that? Am I going in the right direction?
This might seem wierd but, when I try to flare the aircraft manually after closing the throttles at 20 ft, the aircraft begins to climb away from the runway rather than settling down!
I then have to go-around only if I don't stall in the meantime and crash.I have some trouble controlling the aircraft during a crosswind, because I only have a joystick and no rudder pedals for yaw control in MSFS
and it is very inconvenient to use keys to control the rudder. What I've done now is adjusted the joystick so that it gives me both roll and yaw. The aircraft handles better now.
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My comment about advanced technique referred to configuring late in the approach. As you take flap, the aerodynamics change significantly. Try getting the gear and flaps out sooner so that you can be all stable and configured well in advance. Only when you've got this all nailed should you move on to configuring late.
It sounds like you're overdoing the flare. It's only a few extra degrees nose up. Take a look at some youtube videos and you'll see.
Crosswind landings require you to put crossed controls in (wind from left requires right rudder and left aileron) so having the joystick do both won't work all that well (unless you've got a joystick you can twist)
It sounds like you're overdoing the flare. It's only a few extra degrees nose up. Take a look at some youtube videos and you'll see.
Crosswind landings require you to put crossed controls in (wind from left requires right rudder and left aileron) so having the joystick do both won't work all that well (unless you've got a joystick you can twist)
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Originally Posted by welliewanger
My comment about advanced technique referred to configuring late in the approach. As you take flap, the aerodynamics change significantly. Try getting the gear and flaps out sooner so that you can be all stable and configured well in advance. Only when you've got this all nailed should you move on to configuring late.
Originally Posted by welliewanger
It sounds like you're overdoing the flare. It's only a few extra degrees nose up. Take a look at some youtube videos and you'll see.
Originally Posted by welliewanger
Crosswind landings require you to put crossed controls in (wind from left requires right rudder and left aileron) so having the joystick do both won't work all that well (unless you've got a joystick you can twist)
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Visual landings do take practice, especially in MSFS where you do not have all the visual cues you would get in real life.
I would suggest you practice at a larger airport where you have the PAPI lights available (the horizontal line of red/white lights next to the runway). Make sure you have visual on the runway and are lined up nice and early. Good advice from welliewanger to get your configuration set up while you are still in straight and level flight, that way you don't have to worry about adjusting trim etc when you deploy flaps and gear.
As you approach the runway, you will see 4 white lights on the PAPI, then 1 red and 3 whites, then 2 reds and 2 whites. This is the time to start your descent. Gently tilt the nose down and check your speed. The speed will increase as you go "down the slope", so reduce throttle. Try and keep 2 red and 2 white lights until you reach the threshold. 4 whites mean you are too high above the glideslope and 4 reds mean you are too low. Use gentle inputs of throttle and elevator to keep you on the slope.
After a few of these, you will recognise automatically when you are too high or too low from the shape the runway makes ahead of you.
You are right that 250kts is too fast. Slow down well ahead, 180kts would probably be right. If your speed is too high on when you flare, you will climb again as you already found out.
Finally, invest in a good joystick with twist control. I recommend the Logitech Extreme 3D Pro which I have had for many years. You need to have separate axes for rudder and ailerons when you try cross wind landings. Also, get the paid version of FSUIPC by Peter Dowson (from AVSim etc.). This will allow you to adjust the sensitivity of your joystick.
Happy landings!
I would suggest you practice at a larger airport where you have the PAPI lights available (the horizontal line of red/white lights next to the runway). Make sure you have visual on the runway and are lined up nice and early. Good advice from welliewanger to get your configuration set up while you are still in straight and level flight, that way you don't have to worry about adjusting trim etc when you deploy flaps and gear.
As you approach the runway, you will see 4 white lights on the PAPI, then 1 red and 3 whites, then 2 reds and 2 whites. This is the time to start your descent. Gently tilt the nose down and check your speed. The speed will increase as you go "down the slope", so reduce throttle. Try and keep 2 red and 2 white lights until you reach the threshold. 4 whites mean you are too high above the glideslope and 4 reds mean you are too low. Use gentle inputs of throttle and elevator to keep you on the slope.
After a few of these, you will recognise automatically when you are too high or too low from the shape the runway makes ahead of you.
You are right that 250kts is too fast. Slow down well ahead, 180kts would probably be right. If your speed is too high on when you flare, you will climb again as you already found out.
Finally, invest in a good joystick with twist control. I recommend the Logitech Extreme 3D Pro which I have had for many years. You need to have separate axes for rudder and ailerons when you try cross wind landings. Also, get the paid version of FSUIPC by Peter Dowson (from AVSim etc.). This will allow you to adjust the sensitivity of your joystick.
Happy landings!
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When you are visual with the landing runway and surrounding terrain and no doubt exists that continuous visual reference to these features can be maintained until touchdown. 
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A rough rule of thumb is that, for a 'normal' 3 degree glideslope, your rate of descent (in fpm) should be five times your groundspeed (in knots). Therefore if you're doing 150kts then your rate of descent should be 5*150 = 750 feet per minute.
For a 3 degree glidepath, you should descend 300 feet per mile. Therefore at 10 miles from touchdown you should be at 3000'. 5 miles out you should be 1500'.
PAPIs should be set to assist this - look for two red and two white. Four whites means you're too high. Four reds means too low. In the immortal words of David Gunson, four greens means you're seriously low as you're looking through the grass at them!!!!!!!!!!!!
For a 3 degree glidepath, you should descend 300 feet per mile. Therefore at 10 miles from touchdown you should be at 3000'. 5 miles out you should be 1500'.
PAPIs should be set to assist this - look for two red and two white. Four whites means you're too high. Four reds means too low. In the immortal words of David Gunson, four greens means you're seriously low as you're looking through the grass at them!!!!!!!!!!!!
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Steely,
Not quite correct.
PAPIs were not common when that speech was recorded.
David actually referred to their predecessors, called VASI, - Visual Approach Slope Indicators. I believe he described them as "an Ovaltine tin, with a plate welded in at 3 degrees".
Sorry if this sounds a bit pedantic, but to quote 'The Goodies'. -
"GET IT RIGHT".
Not quite correct.
PAPIs were not common when that speech was recorded.
David actually referred to their predecessors, called VASI, - Visual Approach Slope Indicators. I believe he described them as "an Ovaltine tin, with a plate welded in at 3 degrees".
Sorry if this sounds a bit pedantic, but to quote 'The Goodies'. -
"GET IT RIGHT".
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Forget trying to work out 5 x Groundspeed for your rate of descent, just work out ½ groundspeed. It is exactly the same figure, for instance:
Groundspeed = 140kts
5 x 140kts = 700fpm descent rate
½ of 140kts = 700fpm descent rate (ok I know it's 70, but it's an easier calculation)
CC
Groundspeed = 140kts
5 x 140kts = 700fpm descent rate
½ of 140kts = 700fpm descent rate (ok I know it's 70, but it's an easier calculation)
CC
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Originally Posted by computer jockey
Visual landings do take practice, especially in MSFS where you do not have all the visual cues you would get in real life.
Originally Posted by ZOOKER
When you are visual with the landing runway and surrounding terrain and no doubt exists that continuous visual reference to these features can be maintained until touchdown.
Originally Posted by NudgingSteel
A rough rule of thumb is that, for a 'normal' 3 degree glideslope, your rate of descent (in fpm) should be five times your groundspeed (in knots). Therefore if you're doing 150kts then your rate of descent should be 5*150 = 750 feet per minute.
For a 3 degree glidepath, you should descend 300 feet per mile. Therefore at 10 miles from touchdown you should be at 3000'. 5 miles out you should be 1500'.
PAPIs should be set to assist this - look for two red and two white. Four whites means you're too high. Four reds means too low. In the immortal words of David Gunson, four greens means you're seriously low as you're looking through the grass at them!!!!!!!!!!!!
For a 3 degree glidepath, you should descend 300 feet per mile. Therefore at 10 miles from touchdown you should be at 3000'. 5 miles out you should be 1500'.
PAPIs should be set to assist this - look for two red and two white. Four whites means you're too high. Four reds means too low. In the immortal words of David Gunson, four greens means you're seriously low as you're looking through the grass at them!!!!!!!!!!!!
Originally Posted by Coffin Corner
Forget trying to work out 5 x Groundspeed for your rate of descent, just work out ½ groundspeed. It is exactly the same figure, for instance:
Groundspeed = 140kts
5 x 140kts = 700fpm descent rate
½ of 140kts = 700fpm descent rate (ok I know it's 70, but it's an easier calculation)
CC
Groundspeed = 140kts
5 x 140kts = 700fpm descent rate
½ of 140kts = 700fpm descent rate (ok I know it's 70, but it's an easier calculation)
CC
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Originally Posted by One9iner
tune in the ILS frequency and hit APR!
After so many years of keeping in touch with flight deck technology, how come I never thought about that 
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I had a go on MSFS a couple of weeks ago and the A320 did seem far trickier to land than the 737-800. It might be due to me having a better idea about the -400 but the control seemed vague at best.
Regarding speeds...slow down! by 25nm get 210 clean, 20nm get 190 flap 1, 15nm 170 flap5. It doesnt take long to travel...you are doing more than 3 miles a minute. Descend using PAPI or roughly 3 miles for every 1000agl.
Make sure speed is under control, it will float if too fast.
Regarding speeds...slow down! by 25nm get 210 clean, 20nm get 190 flap 1, 15nm 170 flap5. It doesnt take long to travel...you are doing more than 3 miles a minute. Descend using PAPI or roughly 3 miles for every 1000agl.
Make sure speed is under control, it will float if too fast.