Stepped climbs in London airspace.
Supercharged PPRuNer
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Stepped climbs in London airspace.
I'm a UK based Dash 8-400 driver, and our flight ops department, in the interests of fuel-saving, has come up with a number of SOP changes - some of which are more, ahem, contentious than others.
One edict is that we conduct all our climbs at a standard IAS of 210kts to FL150, because: "once every aircraft on the network presents itself to ATC at this speed, stepped climbs should be reduced". Really?
Departing in London airspace, where we are inevitably step-climbed, we usually conduct the initial climb at 210kts, and allow the aircraft to accelerate to around 230kts when level. Once given further climb, particularly a short step such as FL80 to FL100, it is common practice (allegedly) to climb at the higher IAS, be it 220, 230 or whatever. Thus we trade airspeed for climb performance, which to a simple soul like me results in fewer level-offs and power changes. Obviously the above is all subject to weather and ATC requests to expedite etc.
I'd be very interested in hearing an air traffic perspective on this - is it really the case that if all your Dash 8 deltas are climbing at one airspeed, and one airspeed only, we are more likely to get continuous climb?
If only we could get you on the jumpseat for a chat . . .
One edict is that we conduct all our climbs at a standard IAS of 210kts to FL150, because: "once every aircraft on the network presents itself to ATC at this speed, stepped climbs should be reduced". Really?
Departing in London airspace, where we are inevitably step-climbed, we usually conduct the initial climb at 210kts, and allow the aircraft to accelerate to around 230kts when level. Once given further climb, particularly a short step such as FL80 to FL100, it is common practice (allegedly) to climb at the higher IAS, be it 220, 230 or whatever. Thus we trade airspeed for climb performance, which to a simple soul like me results in fewer level-offs and power changes. Obviously the above is all subject to weather and ATC requests to expedite etc.
I'd be very interested in hearing an air traffic perspective on this - is it really the case that if all your Dash 8 deltas are climbing at one airspeed, and one airspeed only, we are more likely to get continuous climb?
If only we could get you on the jumpseat for a chat . . .
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Short answer - NO.
The initial stepped climbs on SIDS are due to the interaction of having 5 (+) busy airports within such a confine.
The stepped climbs you are talking about (FL80-FL100 in this instance) and other similar levels are due to crossing traffic. Doesn't matter what speed you fly at - the crossing traffic will be there.
Some days you get lucky and miss any crossing traffic, others you interact with a lot of aircraft before leaving the LTMA and hence get lots of stepped climbs.
Although a jumpseat ride is agreeable - and a good idea for many reasons, the only real way to understand why climbs are stepped is to visit the centre in question and see it in action.
Crossing traffic is the problem, not aircraft on the same route flying different speeds!
At the very least, the people who come up with these half-baked theories should avail themselves of charts with the route structures drawn on them - I'm sure your local ANSP would be happy to provide them to you as a customer.
The initial stepped climbs on SIDS are due to the interaction of having 5 (+) busy airports within such a confine.
The stepped climbs you are talking about (FL80-FL100 in this instance) and other similar levels are due to crossing traffic. Doesn't matter what speed you fly at - the crossing traffic will be there.
Some days you get lucky and miss any crossing traffic, others you interact with a lot of aircraft before leaving the LTMA and hence get lots of stepped climbs.
Although a jumpseat ride is agreeable - and a good idea for many reasons, the only real way to understand why climbs are stepped is to visit the centre in question and see it in action.
Crossing traffic is the problem, not aircraft on the same route flying different speeds!
At the very least, the people who come up with these half-baked theories should avail themselves of charts with the route structures drawn on them - I'm sure your local ANSP would be happy to provide them to you as a customer.
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Hi SXTY
As a TMA bod working the South sector, I'm thinking particularly of Gatwick departures going either LAM way or through SAM. My quick answer is that IMHO it will not result in fewer step climbs and MAY even have the opposite effect.
My thinking behind this is a bit objective and hard to explain, if only you were in our Ops room so it could be discussed in front of a radar!
Step climbs are sadly a necessity, and as one of the reps on the environmental group I'm aware how inefficient they are. I should emphasise that they effect aircraft of all speeds and although 'props probably have a few more, the difference will be small.
But this small difference is caused by the scenarios where, if you'll entertain my verbose explanation, is where two aircraft depart on laterally conflicting SIDS and the 'prop is the lower of the two, in front of the jet. When the prop in question is flying at a similar speed to the jet, we can entertain the option of climbing it above the jet behind as the catch up is relatively low (eg 230kts v 250kts). There are few props that this option can explored, Dash 8 D's and Saab 2000 being the obvious candidates. However, if the D's start flying significantly slower, this option may be removed.
So my opinion is that a slower airspeed will not result in fewer step climbs. Neither can I think of any reason why the simple change to all Dash 8's flying at the same speed will result in fewer step climbs.
I do hope some of this makes sense, feel free to ask for clarification if it doesn't!
Safe flying
CT
As a TMA bod working the South sector, I'm thinking particularly of Gatwick departures going either LAM way or through SAM. My quick answer is that IMHO it will not result in fewer step climbs and MAY even have the opposite effect.
My thinking behind this is a bit objective and hard to explain, if only you were in our Ops room so it could be discussed in front of a radar!
Step climbs are sadly a necessity, and as one of the reps on the environmental group I'm aware how inefficient they are. I should emphasise that they effect aircraft of all speeds and although 'props probably have a few more, the difference will be small.
But this small difference is caused by the scenarios where, if you'll entertain my verbose explanation, is where two aircraft depart on laterally conflicting SIDS and the 'prop is the lower of the two, in front of the jet. When the prop in question is flying at a similar speed to the jet, we can entertain the option of climbing it above the jet behind as the catch up is relatively low (eg 230kts v 250kts). There are few props that this option can explored, Dash 8 D's and Saab 2000 being the obvious candidates. However, if the D's start flying significantly slower, this option may be removed.
So my opinion is that a slower airspeed will not result in fewer step climbs. Neither can I think of any reason why the simple change to all Dash 8's flying at the same speed will result in fewer step climbs.
I do hope some of this makes sense, feel free to ask for clarification if it doesn't!
Safe flying
CT
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Many thanks for the quick replies.
Cartman's Twin - I'm sure we've spoken to each other! I regularly fly LGW SIDs via LAM, DVR & SAM, and your explanation makes perfect sense.
I had a nasty feeling that this was being driven by people who spend more time with calculators and spreadsheets than flying aeroplanes, and you have confirmed my suspicions.
Cartman's Twin - I'm sure we've spoken to each other! I regularly fly LGW SIDs via LAM, DVR & SAM, and your explanation makes perfect sense.
I had a nasty feeling that this was being driven by people who spend more time with calculators and spreadsheets than flying aeroplanes, and you have confirmed my suspicions.
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I agree with my fellow LTMA Controller, a slow speed may cause more step climbs, due to more catch up.
The only exception I can think of is when asked to expedite the climb when we are interested only in, '' how fast you can climb'', in the verticle profile, which on a LAM dep from KK will often give you a short cut.
Out of KK we are aiming to have you above FL130 abeam LL.
A visit to Swanwick may help the Flight Ops department to see 'how it is done'.
The only exception I can think of is when asked to expedite the climb when we are interested only in, '' how fast you can climb'', in the verticle profile, which on a LAM dep from KK will often give you a short cut.
Out of KK we are aiming to have you above FL130 abeam LL.
A visit to Swanwick may help the Flight Ops department to see 'how it is done'.
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Another factor in the step-climb scenario, is that most current aircraft are outclimbing the vertically layered airspace around and above the London TMA.
The onus then is on the receiving sector to back co-ordinate with the sector above, whose airspace has to be penetrated prior to reaching the receiving sector's boundary.
Frequently the worload can prevent timely back co-ordination or , quite often , it looks like the receiving sector can't be bothered!!
40612
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The onus then is on the receiving sector to back co-ordinate with the sector above, whose airspace has to be penetrated prior to reaching the receiving sector's boundary.
Frequently the worload can prevent timely back co-ordination or , quite often , it looks like the receiving sector can't be bothered!!
40612
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It is, though it takes a bit of organsing. The other way round should be encouraged, espicially representitives from the company that come up with sops.
Surely they must know that flying slower aint going to do diddly squat in preventing you from levelling off, there is a myriad of reasons why you can't get a continous climb. We'd love to do it, but then I spose if we could do it all the time then we would be out of a job!
We were informed that one of these SOPS involves slowing to 210kts in the descent (in areas of low traffic density, to quote the pilot). Well that means when you were once number one you suddenly might become number three. Is that what the SOP designers are aiming for? Do the people that come up with these policies have operational experience or are they people that sit and look at stats?
(Thankfully all the pilots that were involved in this discussion intimated that they all thought the policy was utter rubbish and were perfectly happy to speed up!)
Surely they must know that flying slower aint going to do diddly squat in preventing you from levelling off, there is a myriad of reasons why you can't get a continous climb. We'd love to do it, but then I spose if we could do it all the time then we would be out of a job!
We were informed that one of these SOPS involves slowing to 210kts in the descent (in areas of low traffic density, to quote the pilot). Well that means when you were once number one you suddenly might become number three. Is that what the SOP designers are aiming for? Do the people that come up with these policies have operational experience or are they people that sit and look at stats?
(Thankfully all the pilots that were involved in this discussion intimated that they all thought the policy was utter rubbish and were perfectly happy to speed up!)
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G SXTY - what climb rate will you get if you stick at 210kts? That will certainly come into my planning if you are only doing 1000'/min or less & then I would expect you to level more as it won't be the jet behind I'll be watching now but the 2 or 3 behind that one as well. I like the way the "D"s mix it with the jets fairly smoothly so keep the speed up please 
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It depends on temperature and weight, but as a ball park you can expect 2-3000fpm up to the low hundreds. Accelerating to 230kts loses a little climb performance but not much, and it should still achieve 1500-2000fpm. Alternatively, reducing back to 185kts, we could give you a good 3000fpm.
Lack of horses isn't really a Q400 problem, and it only really starts to run out of puff above around FL150. Even then it climbs reasonably well (up to 1500fpm) right up to the cruise unless we're really heavy and it's ISA plus lots. Given an unrestricted climb I have got to FL250 in 12 minutes from a standing start, which is not bad for a turboprop.
Stepped climbs can be a bit tricky though, for several reasons. Firstly, given the performance available, it is very easy to trigger a TCAS TA in busy airspace, so the climb rate really has to be watched. Secondly, it has a large power / yaw couple, so any power changes necessitate re-trimming the rudder. It's more of a hassle than a problem, but another reason to avoid levelling off. Thirdly, and most importantly, it is very easy to get an alt bust during the altitude acquisition phase (the last few hundred feet of a climb or descent). It's a well known Dash-ism, and thanks to training the situation is much better than it used to be, but in a nutshell the more times we level off, the greater the opportunities to bust the cleared level.
In practice then, if we're at FL80 and cleared to FL100, I would aim to accelerate to 230kts (if not already) and / or reduce the power to achieve around 1000fpm, further reducing the power and climb rate as we get close to the cleared level, hoping for further climb before we level off. If we're given further climb, or you want us to expedite, we can open the taps for a much better RoC.
Your request to keep the speed up is noted.
Someone Else – Don't even get me started on descents! It's actually 200kts flight idle, but there's a little caveat saying it's not suitable in areas of 'high intensity traffic'. One's immediate reaction would be "No sh!t Sherlock." I can just imagine the effect of trundling across the North Sea at 200kts inbound to TANET . . .
As for whoever comes up with these SOPs, I couldn't possibly comment.
Lack of horses isn't really a Q400 problem, and it only really starts to run out of puff above around FL150. Even then it climbs reasonably well (up to 1500fpm) right up to the cruise unless we're really heavy and it's ISA plus lots. Given an unrestricted climb I have got to FL250 in 12 minutes from a standing start, which is not bad for a turboprop.
Stepped climbs can be a bit tricky though, for several reasons. Firstly, given the performance available, it is very easy to trigger a TCAS TA in busy airspace, so the climb rate really has to be watched. Secondly, it has a large power / yaw couple, so any power changes necessitate re-trimming the rudder. It's more of a hassle than a problem, but another reason to avoid levelling off. Thirdly, and most importantly, it is very easy to get an alt bust during the altitude acquisition phase (the last few hundred feet of a climb or descent). It's a well known Dash-ism, and thanks to training the situation is much better than it used to be, but in a nutshell the more times we level off, the greater the opportunities to bust the cleared level.
In practice then, if we're at FL80 and cleared to FL100, I would aim to accelerate to 230kts (if not already) and / or reduce the power to achieve around 1000fpm, further reducing the power and climb rate as we get close to the cleared level, hoping for further climb before we level off. If we're given further climb, or you want us to expedite, we can open the taps for a much better RoC.
Your request to keep the speed up is noted.
Someone Else – Don't even get me started on descents! It's actually 200kts flight idle, but there's a little caveat saying it's not suitable in areas of 'high intensity traffic'. One's immediate reaction would be "No sh!t Sherlock." I can just imagine the effect of trundling across the North Sea at 200kts inbound to TANET . . .
As for whoever comes up with these SOPs, I couldn't possibly comment.
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F-15 Steeped climb
"Yea, Though I Fly Through the Valley of the Shadow of Death, I Shall Fear No Evil. For I am at 50,000 Feet and still Climbing."
hat, coat, eject
"Yea, Though I Fly Through the Valley of the Shadow of Death, I Shall Fear No Evil. For I am at 50,000 Feet and still Climbing."
hat, coat, eject
