V1 Cut obstacle clearance.
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V1 Cut obstacle clearance.
Hellp,
Question for you performance guru's....
IF there is no emergency turn published for a departure in your airline for your aircraft type. What are the basics for performance to clear obstacles? If I'm not mistaken it something like 900m left/right of extended centreline upto 1500AGL, the rest I'm not sure. Any ideas??
Question for you performance guru's....
IF there is no emergency turn published for a departure in your airline for your aircraft type. What are the basics for performance to clear obstacles? If I'm not mistaken it something like 900m left/right of extended centreline upto 1500AGL, the rest I'm not sure. Any ideas??
IF there is no emergency turn published for a departure in your airline for your aircraft type. What are the basics for performance to clear obstacles?
it can take up to 10.4 NM to reach 1500' agl
I know that, For example Old Smokey, assures obstacle clearance to MSA and gives you a place to hold Mutt and John_Tullamarine are also very conservative, but the bare minima are all written up, in your case JAROPS1???
in the past one could add up the total distance of all of the segments and then use obstacle charts to determine max runway weight, but I don't think many folks do it that way anymore
I hope one of the performance guys here can clarify this; but it sounds bad at first glance
PA
Last edited by Pugilistic Animus; 9th Mar 2009 at 19:45.
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Eu Ops
OPS 1.495
Take-off obstacle clearance
(a) An operator shall ensure that the net take-off flight path clears all obstacles by a vertical distance of at least 35 ft or by a horizontal distance of at least 90 m plus 0,125 x D, where D is the horizontal distance the aeroplane has travelled from the end of the take-off distance available or the end of the take-off distance if a turn is scheduled before the end of the take-off distance available. For aeroplanes with a wingspan of less than 60 m a horizontal obstacle clearance of half the aeroplane wingspan plus 60 m, plus 0,125 x D may be used.
Take-off obstacle clearance
(a) An operator shall ensure that the net take-off flight path clears all obstacles by a vertical distance of at least 35 ft or by a horizontal distance of at least 90 m plus 0,125 x D, where D is the horizontal distance the aeroplane has travelled from the end of the take-off distance available or the end of the take-off distance if a turn is scheduled before the end of the take-off distance available. For aeroplanes with a wingspan of less than 60 m a horizontal obstacle clearance of half the aeroplane wingspan plus 60 m, plus 0,125 x D may be used.
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There are several ways to address this problem, this is one person’s approach. Irrespective of the approach taken, all aircraft required to comply with FAR 25 (and it’s equivalents) MUST make full analysis of all obstacles in the Takeoff path until reaching 1500 feet, or a higher altitude if dictated by obstacles.
Ideally (mandatory in some states) this higher safe altitude should be the MSA. (In Australia this is mandated in the AIP, but surprisingly, not in the applicable performance regulations, CAO 20.7.1B).
If we are to contain an EOSID procedure within the MSA altitude constraints, that implies that we must reach Safe Altitude within 25 miles, yet, for a 2 engined aircraft 1st, 2nd, and 3rd segments will often exceed 30 miles. Thus, it may be easily seen that for a 2 engined aircraft at it’s limiting weight, a turn is not desirable, but a necessity if we are to stay within 25 nm.
A certain Obstacle Analysis provider beginning with J (who have a far bigger litigation budget than mine) don’t provide any EOSID if there are no limiting obstacles within 30 miles straight ahead. Fine, but what do you do at 30 miles (often still in the 3rd segment)? I cite Melbourne RWY 34 as an example.” J” sees no problem straight ahead within 30 miles, so, after providing an increased Minimum Acceleration Altitude, lets you go and fly without any special procedure. There might be a mountain at 30.1 miles (there isn’t in this case), but their system does not consider it. What is the MSA? There is none, at 30 miles you have no reference MSA. If you make a Left turn back at MAA (as you would if still in the 3rd segment), terrain contact is a distinct PROBABILITY. If you make a Right turn back, you will survive, but might be deafened by the constant “Terrain, Terrain” calls from the GPWS. Lots of near misses.
The modus operandi that I use in creating EOSIDS is to –
(1) Maintain Runway Track for as long as possible, within terrain constraints, but with a turn (after considering turn radius and lateral splay) inside 25 miles,
(2) After the turn, track to a Holding Pattern shaped “Safe Climb” area, where continued climb to MSA may be conducted. After reaching MSA, FAR 25 et al is discarded, and Pans-OPS (TERPS) take over. Sometimes this is a published Holding Pattern, but more commonly a developed Radio-Nav pattern with the lowest terrain.
(3) This then is the Takeoff Area that I develop, Initial Runway Track (sometimes a Runway end turn), Track or Tracks to a “Safe Climb” Holding Pattern, and the Holding Pattern itself. Throughout this entire Takeoff Area, flight may be conducted at MAA with obstacle clearance assured, even though still below the MSA.
The basic Tracking requirements are as FE Hoppy describes them, i.e. the required Track (NOT HEADING) with a 7 Degree and 8 Minute splay on either side, plus 90M. The Splay continues until intersection with approved Radio Nav Tracking, whereafter the Radio-Nav tolerances apply.
Alternatively, for aircraft with on-board ability to fly Track, the lateral splay may cease upon reaching a nominal parallel margin. (I think that the Australian margin is too small, and use 1852M (1 nm), and 2 nm in the Holding Climb).
Before you can do any of this, you will need a GOOD obstacle analysis, and, guess what? Pilots are not issued with good obstacle data, unless you’ve had it supplied by the Company or a contract supplier. Australia is the exception with good Public Domain Obstacle GRADIENT data from Supplementary Takeoff Distances, but this is limited to 15,000 M (8 miles), a damned good start, but at a 1.6% Gradient, that will only “protect” you for the first 800 feet. After that, you’re on your own to MSA, or Minimum Radar Vectoring Altitude.
The “Normal” data given pilots, e.g. Approach charts are a long way from good enough. They only show the major obstacles, not the smaller “closer in obstacles” that are gonna getcha. Consider a 100 ft radio mast 1 mile from the runway end, being so low it will not be shown on any of the “regular” charts, but, for a 2 engined aircraft it IS a CRITICAL Obstacle after considering 1st Segment. A 500 ft obstacle at 6 miles from the Runway end will probably be shown on the chart, as it is higher. It LOOKS threatening, but, in fact, is not a critical obstacle.
So what to do? First, obtain data for the more dangerous closer in dangerous stuff. Easy in Australia, obtain Type ‘A’ charts elsewhere. (OLS charts are great if you can obtain them. J_T can, but he has friends in high places). After the limit of this closer in (note that I didn’t say close in) data, obtain High detail topographical charts with close contour intervals. For the proposed EOSID, account for the CVA (Chart Vertical Accuracy) at the next highest contour, CHA (Chart Horizontal Accuracy) all the way, build up a series of obstacle “steps”, and finally, obtain the elevation of the highest obstacle in the entire Takeoff Area. To all obstacles, make allowance for trees, man-made structures etc.
Plot the EOSID on the Topo chart, and apply the splay. Consider the maximum and minimum turning radii for all turns in the procedure.
Run a series of Runway Used Vs distance to obstacle performance checks to “zero-in” on the optimum Field/Obstacle limit considering 1st and 2nd segment climbs. Note the LOWEST Gradient usable for the 2nd Segment Climb (Important).
Calculate the height of the Highest Obstacle in the entire Takeoff Area above the Lowest point on the Runway. Multiply this Delta H by the Lowest 2nd Segment Gradient plus 0.8%, and divide by the Lowest 2nd Segment Gradient. Add to this the Highest Runway Elevation + 35 feet (or 50 feet for a Runway End Turn). This is the Minimum Acceleration Altitude (MAA). (I further increase MAA for the lowest AFM Temperature allowed, a cold weather correction, some don’t do this).
That’s the “back of a Postage Stamp” version, there’s a lot more to it, but Danny has band width limitations.
Now, what do you want to do? Aim it and go, hoping for the best, or insist that your operator spend a few (quite a few) bucks on getting proper airport analysis and EOSID development?
VERY IMPORTANT NOTE – The “J” that I spoke of in derogative terms earlier is DEFINATELY NOT John_Tullamarine, he’s a true professional. (Use your imagination).
Fly safe – Avoid the rocks!
Regards,
Old Smokey
Ideally (mandatory in some states) this higher safe altitude should be the MSA. (In Australia this is mandated in the AIP, but surprisingly, not in the applicable performance regulations, CAO 20.7.1B).
If we are to contain an EOSID procedure within the MSA altitude constraints, that implies that we must reach Safe Altitude within 25 miles, yet, for a 2 engined aircraft 1st, 2nd, and 3rd segments will often exceed 30 miles. Thus, it may be easily seen that for a 2 engined aircraft at it’s limiting weight, a turn is not desirable, but a necessity if we are to stay within 25 nm.
A certain Obstacle Analysis provider beginning with J (who have a far bigger litigation budget than mine) don’t provide any EOSID if there are no limiting obstacles within 30 miles straight ahead. Fine, but what do you do at 30 miles (often still in the 3rd segment)? I cite Melbourne RWY 34 as an example.” J” sees no problem straight ahead within 30 miles, so, after providing an increased Minimum Acceleration Altitude, lets you go and fly without any special procedure. There might be a mountain at 30.1 miles (there isn’t in this case), but their system does not consider it. What is the MSA? There is none, at 30 miles you have no reference MSA. If you make a Left turn back at MAA (as you would if still in the 3rd segment), terrain contact is a distinct PROBABILITY. If you make a Right turn back, you will survive, but might be deafened by the constant “Terrain, Terrain” calls from the GPWS. Lots of near misses.
The modus operandi that I use in creating EOSIDS is to –
(1) Maintain Runway Track for as long as possible, within terrain constraints, but with a turn (after considering turn radius and lateral splay) inside 25 miles,
(2) After the turn, track to a Holding Pattern shaped “Safe Climb” area, where continued climb to MSA may be conducted. After reaching MSA, FAR 25 et al is discarded, and Pans-OPS (TERPS) take over. Sometimes this is a published Holding Pattern, but more commonly a developed Radio-Nav pattern with the lowest terrain.
(3) This then is the Takeoff Area that I develop, Initial Runway Track (sometimes a Runway end turn), Track or Tracks to a “Safe Climb” Holding Pattern, and the Holding Pattern itself. Throughout this entire Takeoff Area, flight may be conducted at MAA with obstacle clearance assured, even though still below the MSA.
The basic Tracking requirements are as FE Hoppy describes them, i.e. the required Track (NOT HEADING) with a 7 Degree and 8 Minute splay on either side, plus 90M. The Splay continues until intersection with approved Radio Nav Tracking, whereafter the Radio-Nav tolerances apply.
Alternatively, for aircraft with on-board ability to fly Track, the lateral splay may cease upon reaching a nominal parallel margin. (I think that the Australian margin is too small, and use 1852M (1 nm), and 2 nm in the Holding Climb).
Before you can do any of this, you will need a GOOD obstacle analysis, and, guess what? Pilots are not issued with good obstacle data, unless you’ve had it supplied by the Company or a contract supplier. Australia is the exception with good Public Domain Obstacle GRADIENT data from Supplementary Takeoff Distances, but this is limited to 15,000 M (8 miles), a damned good start, but at a 1.6% Gradient, that will only “protect” you for the first 800 feet. After that, you’re on your own to MSA, or Minimum Radar Vectoring Altitude.
The “Normal” data given pilots, e.g. Approach charts are a long way from good enough. They only show the major obstacles, not the smaller “closer in obstacles” that are gonna getcha. Consider a 100 ft radio mast 1 mile from the runway end, being so low it will not be shown on any of the “regular” charts, but, for a 2 engined aircraft it IS a CRITICAL Obstacle after considering 1st Segment. A 500 ft obstacle at 6 miles from the Runway end will probably be shown on the chart, as it is higher. It LOOKS threatening, but, in fact, is not a critical obstacle.
So what to do? First, obtain data for the more dangerous closer in dangerous stuff. Easy in Australia, obtain Type ‘A’ charts elsewhere. (OLS charts are great if you can obtain them. J_T can, but he has friends in high places). After the limit of this closer in (note that I didn’t say close in) data, obtain High detail topographical charts with close contour intervals. For the proposed EOSID, account for the CVA (Chart Vertical Accuracy) at the next highest contour, CHA (Chart Horizontal Accuracy) all the way, build up a series of obstacle “steps”, and finally, obtain the elevation of the highest obstacle in the entire Takeoff Area. To all obstacles, make allowance for trees, man-made structures etc.
Plot the EOSID on the Topo chart, and apply the splay. Consider the maximum and minimum turning radii for all turns in the procedure.
Run a series of Runway Used Vs distance to obstacle performance checks to “zero-in” on the optimum Field/Obstacle limit considering 1st and 2nd segment climbs. Note the LOWEST Gradient usable for the 2nd Segment Climb (Important).
Calculate the height of the Highest Obstacle in the entire Takeoff Area above the Lowest point on the Runway. Multiply this Delta H by the Lowest 2nd Segment Gradient plus 0.8%, and divide by the Lowest 2nd Segment Gradient. Add to this the Highest Runway Elevation + 35 feet (or 50 feet for a Runway End Turn). This is the Minimum Acceleration Altitude (MAA). (I further increase MAA for the lowest AFM Temperature allowed, a cold weather correction, some don’t do this).
That’s the “back of a Postage Stamp” version, there’s a lot more to it, but Danny has band width limitations.
Now, what do you want to do? Aim it and go, hoping for the best, or insist that your operator spend a few (quite a few) bucks on getting proper airport analysis and EOSID development?
VERY IMPORTANT NOTE – The “J” that I spoke of in derogative terms earlier is DEFINATELY NOT John_Tullamarine, he’s a true professional. (Use your imagination).
Fly safe – Avoid the rocks!
Regards,
Old Smokey
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Reminds me of when I flew the 737 Classic for a German charter operator. The runway analysis for a Greek island required a curved take off procedure through 90 degrees which was over the water. Flap retract height was 800 feet. Nothing else mentioned. Only problem was another island dead ahead at 10 miles from the departure runway with a spot height of around 1500 feet dead on track. In IMC we would have gone in during the acceleration phase.
On return to base I asked the performance engineers how come the spot height of 1500 ft was not taken into account? Their reply was the Greek CAA supplied obstacle charts did not include the island on track. The performance engineers said it was up to the pilots to know about the spot height and turn to avoid it.
On return to base I asked the performance engineers how come the spot height of 1500 ft was not taken into account? Their reply was the Greek CAA supplied obstacle charts did not include the island on track. The performance engineers said it was up to the pilots to know about the spot height and turn to avoid it.
Moderator
If I may add some comments to OS's comprehensive post..
(a) MUST make full analysis of all obstacles in the Takeoff path until reaching 1500 feet, or a higher altitude if dictated by obstacles.
It is a great concern that many operators don't worry too much about this ... ie there is some good fortune associated with the reliability of modern aircraft.
(b) In Australia this is mandated in the AIP, but surprisingly, not in the applicable performance regulations, CAO 20.7.1B.
The operational implementation (20.7.1B) of the airworthiness requirement (101.5/6 - now long gone) made inference of such a requirement. The AIP words were introduced quite some years ago by a Canberra operations chap motivated by the best of honorable intentions but not much background understanding of the realities of the engineering. The amendment was made to require the GA pilot to play operations engineer with his light twins in a manner roughly similar to what the airlines did with their far greater resources. After considerable argument I got agreement from higher up the chain to rescind the amendment (which I thought was a bit onerous and impracticable) .. however, as often happens, behind the scenes backroom manoevring saw that squashed and I eventually gave up .. however, I did frame the letter so that I could have the occasional giggle over the whole matter ...
(b) will often exceed 30 miles.
For a critical twin OEI operation, 50 miles is a useful ROM for the distance to a useful height (we all used to cite the Diesel 9 as being the archetypical example of this ..
but a necessity if we are to stay within 25 nm.
The alternative is to do a lot of obstacle work yourself for those difficult places ..
(c) A certain Obstacle Analysis provider
If I am inferring who OS is referring to correctly, I would say that, on the basis of an audit I did quite some years ago, they do a good job in what they do .. but, as cited by OS, there is a gap between that and what would be nice (necessary ?) to have for the operation. There were reasons for their policy and, if I am reading OS correctly, I am surprised that they haven't varied the approach as we had some detailed discussions on just this sort of problem.
(d) Australia is the exception with good Public Domain Obstacle GRADIENT data from Supplementary Takeoff Distances
As the surveys normally are done in the conventional manner, rather than being a strict inclinometer survey, the published gradients are calculated from the (x,y,z) triplets .. so, if you ask the right person .. you can get the specified obstacle data.
(e) So what to do? First, obtain data
And if you still don't have adequate data, you throw a theodolite over the shoulder and go bush for the time it takes to run a check survey to satisfy yourself that the data you propose to use is OK.
(f) Now, what do you want to do? Aim it and go, hoping for the best, or insist that your operator spend a few (quite a few) bucks on getting proper airport analysis and EOSID development?
This is an underlying consideration that OS, Mutt and I keeping trying to push in these sort of PPRuNe threads .. while there is no reason why a non-engineer pilot who knows the ropes can't do the work (and Tee Emm, in the previous post, is an example I could cite) the majority of pilots don't have the training or knowledge to do so. Far too often we hear tales from pilot colleagues (more so in the corporate/GA sector, but sometimes with the scheduled carriers) involving eyeballing a departure rather than doing the sums in a rational and constructive manner. It just doesn't work that way unless you are driving an F18 or similar triumph of thrust over aerodynamics .. The fact that we don't see CFITs day in day out is a reflection of aircraft engine reliability more than anything else.
Tee Emm's example is not atypical and that worthy gentleman can cite quite a few other operator instances of less than desirable policies from his very lengthy experience with a variety of airlines ...
(a) MUST make full analysis of all obstacles in the Takeoff path until reaching 1500 feet, or a higher altitude if dictated by obstacles.
It is a great concern that many operators don't worry too much about this ... ie there is some good fortune associated with the reliability of modern aircraft.
(b) In Australia this is mandated in the AIP, but surprisingly, not in the applicable performance regulations, CAO 20.7.1B.
The operational implementation (20.7.1B) of the airworthiness requirement (101.5/6 - now long gone) made inference of such a requirement. The AIP words were introduced quite some years ago by a Canberra operations chap motivated by the best of honorable intentions but not much background understanding of the realities of the engineering. The amendment was made to require the GA pilot to play operations engineer with his light twins in a manner roughly similar to what the airlines did with their far greater resources. After considerable argument I got agreement from higher up the chain to rescind the amendment (which I thought was a bit onerous and impracticable) .. however, as often happens, behind the scenes backroom manoevring saw that squashed and I eventually gave up .. however, I did frame the letter so that I could have the occasional giggle over the whole matter ...
(b) will often exceed 30 miles.
For a critical twin OEI operation, 50 miles is a useful ROM for the distance to a useful height (we all used to cite the Diesel 9 as being the archetypical example of this ..
but a necessity if we are to stay within 25 nm.
The alternative is to do a lot of obstacle work yourself for those difficult places ..
(c) A certain Obstacle Analysis provider
If I am inferring who OS is referring to correctly, I would say that, on the basis of an audit I did quite some years ago, they do a good job in what they do .. but, as cited by OS, there is a gap between that and what would be nice (necessary ?) to have for the operation. There were reasons for their policy and, if I am reading OS correctly, I am surprised that they haven't varied the approach as we had some detailed discussions on just this sort of problem.
(d) Australia is the exception with good Public Domain Obstacle GRADIENT data from Supplementary Takeoff Distances
As the surveys normally are done in the conventional manner, rather than being a strict inclinometer survey, the published gradients are calculated from the (x,y,z) triplets .. so, if you ask the right person .. you can get the specified obstacle data.
(e) So what to do? First, obtain data
And if you still don't have adequate data, you throw a theodolite over the shoulder and go bush for the time it takes to run a check survey to satisfy yourself that the data you propose to use is OK.
(f) Now, what do you want to do? Aim it and go, hoping for the best, or insist that your operator spend a few (quite a few) bucks on getting proper airport analysis and EOSID development?
This is an underlying consideration that OS, Mutt and I keeping trying to push in these sort of PPRuNe threads .. while there is no reason why a non-engineer pilot who knows the ropes can't do the work (and Tee Emm, in the previous post, is an example I could cite) the majority of pilots don't have the training or knowledge to do so. Far too often we hear tales from pilot colleagues (more so in the corporate/GA sector, but sometimes with the scheduled carriers) involving eyeballing a departure rather than doing the sums in a rational and constructive manner. It just doesn't work that way unless you are driving an F18 or similar triumph of thrust over aerodynamics .. The fact that we don't see CFITs day in day out is a reflection of aircraft engine reliability more than anything else.
Tee Emm's example is not atypical and that worthy gentleman can cite quite a few other operator instances of less than desirable policies from his very lengthy experience with a variety of airlines ...
One question???
Would one of you like to comment on the US DACS digital obstacle data? it's utility in performance engineering , sorry for the quality of this post but I MUST GO !!!
pa
Would one of you like to comment on the US DACS digital obstacle data? it's utility in performance engineering , sorry for the quality of this post but I MUST GO !!!
pa
OS & J_T
If I may add a plug for a company in Colorado that does runway analysis for operators based on FAA AC 120-91, Runway Analysis. My employer subscribes, it is Ops Manual requirement to use them. I have found them very good, once each pilot has received training on the problem and the analysis. In the spirit of the thread, the company is A.P.G.; also available if one subscribes to brand AR Incorporated flight planning.
GF
If I may add a plug for a company in Colorado that does runway analysis for operators based on FAA AC 120-91, Runway Analysis. My employer subscribes, it is Ops Manual requirement to use them. I have found them very good, once each pilot has received training on the problem and the analysis. In the spirit of the thread, the company is A.P.G.; also available if one subscribes to brand AR Incorporated flight planning.
GF
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Old Smokey -
Thank you for your "postage stamp" reply... you must have very large postage stamps where you are!
To those here who are "in the know" (ie OS, J_T, mutt etc) do you think that leaving the preparation of this data for individual airlines should be how it is done? Or should all places that provide IFR departures also have a standard EOSID published, so that everybody (crew and ATC) are on the same page when faced with the engine failure on takeoff?
As I'm sure you are aware a lot of airlines don't really put the appropriate emphasis on preparing these contingencies (whether it be through complacency or the sheer difficulty in obtaining data and accessing currently qualified individuals able to prepare these plans) so should state aviation authorities be putting more emphasis on it?
I know it would cause headaches with different airlines favouring different methods, but it seems odd to me that something that is so critical to flight safety is so widely misunderstood by pilots and inadequately considered by airlines, and that the governing bodies don't produce their own charts.
Thank you for your "postage stamp" reply... you must have very large postage stamps where you are!
To those here who are "in the know" (ie OS, J_T, mutt etc) do you think that leaving the preparation of this data for individual airlines should be how it is done? Or should all places that provide IFR departures also have a standard EOSID published, so that everybody (crew and ATC) are on the same page when faced with the engine failure on takeoff?
As I'm sure you are aware a lot of airlines don't really put the appropriate emphasis on preparing these contingencies (whether it be through complacency or the sheer difficulty in obtaining data and accessing currently qualified individuals able to prepare these plans) so should state aviation authorities be putting more emphasis on it?
I know it would cause headaches with different airlines favouring different methods, but it seems odd to me that something that is so critical to flight safety is so widely misunderstood by pilots and inadequately considered by airlines, and that the governing bodies don't produce their own charts.
Moderator
Or should all places ... also have a standard EOSID published
No reason why not (unless it's changed, one could cite 30 HBA as a for instance, although that's all departures ..AEO and OEI). However, the commercial reality is that one size doesn't fit all due to engine/airframe differences .. each needs to be optimised to the location if the airline is to end up with a "good" RTOW.
state aviation authorities be putting more emphasis on it?
Nice thought but an operator responsibility so I fear that few Regulators will want to get involved.
so widely misunderstood by pilots and inadequately considered by airlines
A matter of corporate will and training. I'm sure that Mutt, OS, and I have spent quite a considerable effort over the years in educating those operator crews for whom we have provided charts ... unfortunately many pilots are given minimalist training and some operators appear not to know what they don't know ...
No reason why not (unless it's changed, one could cite 30 HBA as a for instance, although that's all departures ..AEO and OEI). However, the commercial reality is that one size doesn't fit all due to engine/airframe differences .. each needs to be optimised to the location if the airline is to end up with a "good" RTOW.
state aviation authorities be putting more emphasis on it?
Nice thought but an operator responsibility so I fear that few Regulators will want to get involved.
so widely misunderstood by pilots and inadequately considered by airlines
A matter of corporate will and training. I'm sure that Mutt, OS, and I have spent quite a considerable effort over the years in educating those operator crews for whom we have provided charts ... unfortunately many pilots are given minimalist training and some operators appear not to know what they don't know ...
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I wondered why I couldn't reply J_T, it seems that we were replying together!
A Comfy Chair, you've asked a very good question, one which I've discussed with one of these forums "Normal" procedure designers. I don't think that Oz_Expat would mind my re-telling some of his wise words, mixed with those (just posted) by J_T) and a few of my own.
There are far too many variables between aircraft types to create standard "Government Issue" OESIDs. Consider, for example, that the performance requirements for 2,3, and 4 engined aircraft are markedly different. A limiting obstacle for a 2 engined aircraft may require an early turn, whereas the same obstacle may not be critical for the 4 engined aircraft with it's increased climb gradient requirement and capability. To impose the increased climb requirement on the twin would limit it's payload carrying ability.
Consider also the very wide range of speeds flown by commercial aircraft. One aircraft that I do work for has a maximum V2 of 130 Kt, another has a maximum V2 approaching 180 Kt, a massive difference in turn radius, which will require different turning points for the OEISID. Hobart 30 (which I've done work for, and referred to by J_T) is a very good example. Minimum V2 has a similar effect for the "inside" splay. Again, we would be imposing another aircraft's limits on one type for the sake of uniformity, with associated penalties.
My favourite project relating to the turn radius problem was at Petropavlosk Chamkatsky (UHPP) in Eastern Russia. The OEISID requires a LARGE radius turn to contain the procedure within a "bowl" of very high mountains, but circumnavigating a large "hump" in the middle. For the B777 at the nominal OEI 15 degrees of bank at it's much higher speeds, it was a very standard calculation. For another much slower aircraft, the same very precise turn required 9 degrees of bank, a big "ask" for the operating pilots. The solution for the slower aircraft was to create precise Lat and Long for a series of FMC/FMS waypoints, and to fly the procedure using LNAV (in a non-WGS84 country).
A further problem arises due to Takeoff Thrust Time Limitations. At a very obstacle strewn airport in the land of Oz, I spent days finding the optimum escape route to avoid the obstacles, all of which required a fairly large Acceleration Altitude. The aircraft I was working for had a 5 minute Takeoff Thrust Limit, and further calculations found that the 5 minute limit would be reached just upon achieving MAA, with no excess for acceleration. After all of the work, the only solution was to impose a much higher Gradient requirement to reach MAA sooner (greatly out-climbing the obstacles), allowing for acceleration to Vcl. If a 10 minute Takeoff Thrust Limit aircraft had the same requirement imposed, again that aircraft would pay the price for complying with another aircraft's requirements.
To cut a long story short, no, one size does not fit all. There are many airports (e.g. over water) where it could, but this would be the exception.
I've recently had an email from a client who is changeing their aircraft type to one with a totally different speed range. His enquiry was "Can we continue to use the existing OEISIDs?". My reply was "We start from scratch". He hasn't replied yet!
A damned good proposal Comfy Chair, I wish it were possible.
Regards,
Old Smokey
A Comfy Chair, you've asked a very good question, one which I've discussed with one of these forums "Normal" procedure designers. I don't think that Oz_Expat would mind my re-telling some of his wise words, mixed with those (just posted) by J_T) and a few of my own.
There are far too many variables between aircraft types to create standard "Government Issue" OESIDs. Consider, for example, that the performance requirements for 2,3, and 4 engined aircraft are markedly different. A limiting obstacle for a 2 engined aircraft may require an early turn, whereas the same obstacle may not be critical for the 4 engined aircraft with it's increased climb gradient requirement and capability. To impose the increased climb requirement on the twin would limit it's payload carrying ability.
Consider also the very wide range of speeds flown by commercial aircraft. One aircraft that I do work for has a maximum V2 of 130 Kt, another has a maximum V2 approaching 180 Kt, a massive difference in turn radius, which will require different turning points for the OEISID. Hobart 30 (which I've done work for, and referred to by J_T) is a very good example. Minimum V2 has a similar effect for the "inside" splay. Again, we would be imposing another aircraft's limits on one type for the sake of uniformity, with associated penalties.
My favourite project relating to the turn radius problem was at Petropavlosk Chamkatsky (UHPP) in Eastern Russia. The OEISID requires a LARGE radius turn to contain the procedure within a "bowl" of very high mountains, but circumnavigating a large "hump" in the middle. For the B777 at the nominal OEI 15 degrees of bank at it's much higher speeds, it was a very standard calculation. For another much slower aircraft, the same very precise turn required 9 degrees of bank, a big "ask" for the operating pilots. The solution for the slower aircraft was to create precise Lat and Long for a series of FMC/FMS waypoints, and to fly the procedure using LNAV (in a non-WGS84 country).
A further problem arises due to Takeoff Thrust Time Limitations. At a very obstacle strewn airport in the land of Oz, I spent days finding the optimum escape route to avoid the obstacles, all of which required a fairly large Acceleration Altitude. The aircraft I was working for had a 5 minute Takeoff Thrust Limit, and further calculations found that the 5 minute limit would be reached just upon achieving MAA, with no excess for acceleration. After all of the work, the only solution was to impose a much higher Gradient requirement to reach MAA sooner (greatly out-climbing the obstacles), allowing for acceleration to Vcl. If a 10 minute Takeoff Thrust Limit aircraft had the same requirement imposed, again that aircraft would pay the price for complying with another aircraft's requirements.
To cut a long story short, no, one size does not fit all. There are many airports (e.g. over water) where it could, but this would be the exception.
I've recently had an email from a client who is changeing their aircraft type to one with a totally different speed range. His enquiry was "Can we continue to use the existing OEISIDs?". My reply was "We start from scratch". He hasn't replied yet!
A damned good proposal Comfy Chair, I wish it were possible.
Regards,
Old Smokey
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PS Pugilistic Animus and galaxy flyer,
Thank you both for the excellent references. Expect a PM as soon as my present 25 hours per day roster drops back to a normal frenzy.
You certainly have my interest.
P A, long long overdue email. I haven't forgotten to reply
Regards,
Old Smokey
Thank you both for the excellent references. Expect a PM as soon as my present 25 hours per day roster drops back to a normal frenzy.
You certainly have my interest.
P A, long long overdue email. I haven't forgotten to reply
Regards,
Old Smokey
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"Can we continue to use the existing OEISIDs?"
It makes life easier, especially as we operate about 12 aircraft types!
Mutt
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A good proposal, as usual Mutt, and certainly achievable within one airline, albeit with 12 types. We're in a fairly similar position, with 9 types in the main airline and it's subsidiaries..
The problem arises when the system goes global, and we're trying to accomodate ALL types, from light jets through to heavy metal, 2,3, and 4 engines, 5 and 10 minute T/O Thrust limits, and widely differing operating speeds.
An example - We once chatted about Surabaya, where both of our companys fly to. The discussion was about use of Clearway, not obstacles (which aren't a particular problem there), but it's an example. If we created an "all embracing" procedure there to cover the "worst performing" type, it wouldn't worry us at all, we only have to fly 90 minutes from there to our hub, and even a hefty RTOW penalty wouldn't really matter. For you, however, with about 10 hours to destination, you'll probably be scratching for the last Kg of RTOW, and cursing the more conservative analysis for the worst case aircraft.
Perhaps the ideal compromise is to create a "Government Issue" OEISID for each runway, with individual operators reserving the right to re-develop their own procedure if the standard procedure was too limiting.
Regards,
Old Smokey
Oz-Expat, where the hell are you when we need you?
The problem arises when the system goes global, and we're trying to accomodate ALL types, from light jets through to heavy metal, 2,3, and 4 engines, 5 and 10 minute T/O Thrust limits, and widely differing operating speeds.
An example - We once chatted about Surabaya, where both of our companys fly to. The discussion was about use of Clearway, not obstacles (which aren't a particular problem there), but it's an example. If we created an "all embracing" procedure there to cover the "worst performing" type, it wouldn't worry us at all, we only have to fly 90 minutes from there to our hub, and even a hefty RTOW penalty wouldn't really matter. For you, however, with about 10 hours to destination, you'll probably be scratching for the last Kg of RTOW, and cursing the more conservative analysis for the worst case aircraft.
Perhaps the ideal compromise is to create a "Government Issue" OEISID for each runway, with individual operators reserving the right to re-develop their own procedure if the standard procedure was too limiting.
Regards,
Old Smokey
Oz-Expat, where the hell are you when we need you?
OS
Very good idea on standardized OEI procedures with individual operators customizing it for their particular aircraft and operation. In fact, Rio's Galeao (SBGL) did have published OEI procedures, issued by Brasil's CAA, as part of their SIDs. I planned several USAF missions out of there with MTOGW issues for C-5s and the procedures were operational advantageous. This was before we had service provider J's OEI procedures. I don't have access to a Jepp subscription at home, but will look, next I'm in the office.
GF
Very good idea on standardized OEI procedures with individual operators customizing it for their particular aircraft and operation. In fact, Rio's Galeao (SBGL) did have published OEI procedures, issued by Brasil's CAA, as part of their SIDs. I planned several USAF missions out of there with MTOGW issues for C-5s and the procedures were operational advantageous. This was before we had service provider J's OEI procedures. I don't have access to a Jepp subscription at home, but will look, next I'm in the office.
GF
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Good solution for GA
I have a big question for you experts:
In the airtaxi ops we go all over the world with very short notice.
We are not able to estabilish contingency procedures for various reasons, AFMs are very complicated, AIPs are not available.
How can we do to have a contingency procedures available for a runway in a couple of hours ?
Can we use the SID single engine ? if gradients bigger than 3.3 is required for "noise" or "ATC" does it means that obstacles require still 3.3 ?
I have found something "web-based" but it is to have a MTOM for runway and segments, contingency procedure is only made available for some particulars situations. Another company offer the service but they require to much time.
Thanks
How can I estabilish a safe procedure to come back to the airport ?
In the airtaxi ops we go all over the world with very short notice.
We are not able to estabilish contingency procedures for various reasons, AFMs are very complicated, AIPs are not available.
How can we do to have a contingency procedures available for a runway in a couple of hours ?
Can we use the SID single engine ? if gradients bigger than 3.3 is required for "noise" or "ATC" does it means that obstacles require still 3.3 ?
I have found something "web-based" but it is to have a MTOM for runway and segments, contingency procedure is only made available for some particulars situations. Another company offer the service but they require to much time.
Thanks
How can I estabilish a safe procedure to come back to the airport ?
Last edited by gigi116; 15th Mar 2009 at 01:28.
We use APG out of Castle Rock, CO, USA. Absolutely excellent, service is done on-line or thru Blackberry link, they can fax it and, if you subscribe to ARINC Flight Planning service, it is on their website. Analysis is done virtually immediately, in my experience over two years. Special procedures are included, if needed. They are used by charter operators, airlines and corporate flight departments.
PM, me if I can be of assistance
GF
Danny does NOT endorse this or any other product.
To be consistent, I have removed the APG link. However, Mr Google can provide it (in an instant) for those who may be interested. - JT
PM, me if I can be of assistance
GF
Danny does NOT endorse this or any other product.
To be consistent, I have removed the APG link. However, Mr Google can provide it (in an instant) for those who may be interested. - JT
Moderator
How can we do to have a contingency procedures available for a runway in a couple of hours ?
That is the problem over which all reputable operators concern themselves. There is no easy way around the problem and all solutions cost resources both in terms of dollars and time.
There are various organisations around who will do the work for a dollar (or many) or you can train up internal resources to do the work. The difficulty is not with the actual calculations .. they are comparatively straightforward and can be done either manually or via computer. The latter requires either the OEM performance package or the development either of lookup tables or regression equations to fit the AFM data).
The routine effort has to be directed towards getting adequate obstacle data. Generally, and especially if you don't need the very last kilo, you can run up a one off calculation without too much delay .. once you have decided that your obstacle profile is of sufficient accuracy.
Can we use the SID single engine ?
Of course, provided that you match the actual obstruction profile to your aircraft's capability and accept whatever RTOWs fall out of the sausage machine. A side issue relates to imposing an increased level of precision on turning points ..
That is the problem over which all reputable operators concern themselves. There is no easy way around the problem and all solutions cost resources both in terms of dollars and time.
There are various organisations around who will do the work for a dollar (or many) or you can train up internal resources to do the work. The difficulty is not with the actual calculations .. they are comparatively straightforward and can be done either manually or via computer. The latter requires either the OEM performance package or the development either of lookup tables or regression equations to fit the AFM data).
The routine effort has to be directed towards getting adequate obstacle data. Generally, and especially if you don't need the very last kilo, you can run up a one off calculation without too much delay .. once you have decided that your obstacle profile is of sufficient accuracy.
Can we use the SID single engine ?
Of course, provided that you match the actual obstruction profile to your aircraft's capability and accept whatever RTOWs fall out of the sausage machine. A side issue relates to imposing an increased level of precision on turning points ..