Limiting Factors For Takeoff
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mutt:
Well...the 767 is still rolling off the Boeing assembly lines, albeit with a lot better FMS. But, many airlines operate exactly the same version of the 767 I flew and with their fleet mixed with the Pegasus 767.
I don't see where today's "gee wiz" stuff has improved the OEI case all that much. The big improvements are better autopilots (but not that much better than the 767 I flew) RNP AR, LPV, RVSM, EGPWS, and TCAS. Auto checklists are great, too. Electronic charts are just a vector graphics presentation of a 1950s chart. Until database charts arrive, there is not much improvement there, other than pilots not misplacing paper charts.
The last thing I would do is improvise the takeoff flight path profile in the event of OEI. TWA mandated clean-up at 1,000 feet, and that is what we did. (They used 800 feet in the earlier days). So, the 31 mile performance data they provided to our safety committee was based on clean up at 1,000. In any case, there is no way, no matter what you did, that 727 would have cleared the second range of mountains west of KLAS.
Next, a friendly poke at you engineers: in mountainous terrain their are more holes than in Swizz cheese in the calculation/guidance in the en route climb requirements from completion of the end of the takeoff flight path until reaching the effective minimum safe instrument altitude. And, Part 121 is ancient in still requiring 5 miles each side of centerline for OEI en route. On the one hand that regulation mandates only 300 feet each side centerline for the takeoff flight path, but it requires an absurdly wide 5 miles after the takeoff flight path. I don't see anyone doing an adequate job on the en route climb phase.
Finally, since I work with RNAV issues in my present life, we (industry and FAA) are constantly finding inconsistencies in FMS implementation issues across the larger fleet. And, in spite of what you imply, much of today's U.S. air carrier fleet consists of aircraft no more capable than the old-generation 767 I flew. In fact, one of the very big airlines cannot fly LNAV/VNAV IAPs because they don't train their crews because of these mixed fleet issues (i.e., a whole lot of the older segment of their fleet does not have GPS sensing, rather they have DME/DME updating which I used in 1984.) (The OEMs charge a fortune to update FMSes.)
aterpster, your list of aircraft are all old generation aircraft
With new generation aircraft we also got new generation software, including electronic airplane flight manuals. The situations that you have detailed for LAS and RENO, need not exist today.
Another question, if you aircraft was capable of achieving 231 feet/nm and you wished to climb to 1500 feet, why did it take 31 nms? Why not use extended second segment and climb to 1500 feet before accelerating? YOu would make less noise that way (i.e not hit the mountain.)
Next, a friendly poke at you engineers: in mountainous terrain their are more holes than in Swizz cheese in the calculation/guidance in the en route climb requirements from completion of the end of the takeoff flight path until reaching the effective minimum safe instrument altitude. And, Part 121 is ancient in still requiring 5 miles each side of centerline for OEI en route. On the one hand that regulation mandates only 300 feet each side centerline for the takeoff flight path, but it requires an absurdly wide 5 miles after the takeoff flight path. I don't see anyone doing an adequate job on the en route climb phase.
Finally, since I work with RNAV issues in my present life, we (industry and FAA) are constantly finding inconsistencies in FMS implementation issues across the larger fleet. And, in spite of what you imply, much of today's U.S. air carrier fleet consists of aircraft no more capable than the old-generation 767 I flew. In fact, one of the very big airlines cannot fly LNAV/VNAV IAPs because they don't train their crews because of these mixed fleet issues (i.e., a whole lot of the older segment of their fleet does not have GPS sensing, rather they have DME/DME updating which I used in 1984.) (The OEMs charge a fortune to update FMSes.)
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300 feet horizontally after passing the boundaries.
The 767 came with Mark7 performance software which is extremely limited in its capabilities, hence the reason i consider it an old generation aircraft.
The "gee whiz" that came with newer aircraft is our ability to calculate takeoff flight paths with greater accuracy, we can also account for wind from various quadrants. We end up suffering from greater payload reductions than required by regulation, but we are satisfied that OEI procedures can be flown under all circumstances.
As for the mountainous terrain, whats wrong with turning the aircraft around and returning it to the airport? We have a habit of ending OEI procedures over a defined point in order to ensure that all obstacles are accounted for, rather than jump into a 5 mile cone without accurate information.
I don't see anyone doing an adequate job on the en route climb phase.
Mutt
Last edited by mutt; 27th May 2010 at 17:08.
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mutt:
As to accurate information, 1:24,000 topo quads are available for the entire U.S., except Alaska which is (I believe) still pretty good with 15 minute quads. In other parts of the world the data are limited to a varying degree, in spite of the U.S. taxpayers having spent a bundle on the Shuttle mission that obtain good topo data.
As to turning around and landing, that often is not a very good idea. Even when it's day VFR some mountain airports have a severe balked landing obstacle environment. So, the crew may want to proceed, for example, to Montrose or Grand Junction rather than returning to Aspen, Eagle, Hayden, Gunnison or Rifle.
If the weather is IMC the departure may have been made at standard takeoff minimums, which are usually well below landing minimums in the mountains. And, that often holds true even at many flat-land airports, thus the requirement for two-engine bird to have a takeoff alternate in such circumstances.
Further, in the mountains, the end of the takeoff flight path may be too low to turn around in either VMC or especially in IMC to get to the appropriate instrument approach procedure IAF.
Don't know those acronyms. 
As for the mountainous terrain, whats wrong with turning the aircraft around and returning it to the airport? We have a habit of ending OEI procedures over a defined point in order to ensure that all obstacles are accounted for, rather than jump into a 5 mile cone without accurate information.
As to turning around and landing, that often is not a very good idea. Even when it's day VFR some mountain airports have a severe balked landing obstacle environment. So, the crew may want to proceed, for example, to Montrose or Grand Junction rather than returning to Aspen, Eagle, Hayden, Gunnison or Rifle.
If the weather is IMC the departure may have been made at standard takeoff minimums, which are usually well below landing minimums in the mountains. And, that often holds true even at many flat-land airports, thus the requirement for two-engine bird to have a takeoff alternate in such circumstances.
Further, in the mountains, the end of the takeoff flight path may be too low to turn around in either VMC or especially in IMC to get to the appropriate instrument approach procedure IAF.
Very true......but with the introduction of BCOPS and PEP that might change.
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J_T and Mutt:
War-story department: One of my pals was flying a flight out of KABQ on a hot summer day (wx CAVU). It was a 727-100 (20,000 pounds less max structural weight than the -200, but with the same engines). As I recall they were at MGTOW of 152,000. Fortunately, they were taking off on Runway 26 (which descends to the Rio Grande River west of the field). On rotation they shedded a tire into one of the outboard engines, which of course failed in a nasty manner. Being sharp guys, they briefed the OEI profile again and found that the airplane just hung at zero climb rate at V2, then the speed started to slowly decay. So, the PF dropped the nose to regain speed (that would have been a hull loss on Runway 8) and then gently banked left to turn south along the river. The airplane then managed to stay level at somewhat over V2 then after a few miles very slowly began to climb. They went south about 20 miles before they could clean up, at which time performance picked up and they were able to climb sufficiently to turn around and return to the field.
That one was kept real quiet.
I believe it was the awesome reliability of jet engines that kept us from disaster over the years. I had three engine failures (or mandatory shut-downs) over 27 years, and only one was on takeoff (L1011 center engine failed at 2,900 agl after clean up to 250 knots.)
War-story department: One of my pals was flying a flight out of KABQ on a hot summer day (wx CAVU). It was a 727-100 (20,000 pounds less max structural weight than the -200, but with the same engines). As I recall they were at MGTOW of 152,000. Fortunately, they were taking off on Runway 26 (which descends to the Rio Grande River west of the field). On rotation they shedded a tire into one of the outboard engines, which of course failed in a nasty manner. Being sharp guys, they briefed the OEI profile again and found that the airplane just hung at zero climb rate at V2, then the speed started to slowly decay. So, the PF dropped the nose to regain speed (that would have been a hull loss on Runway 8) and then gently banked left to turn south along the river. The airplane then managed to stay level at somewhat over V2 then after a few miles very slowly began to climb. They went south about 20 miles before they could clean up, at which time performance picked up and they were able to climb sufficiently to turn around and return to the field.
That one was kept real quiet.
I believe it was the awesome reliability of jet engines that kept us from disaster over the years. I had three engine failures (or mandatory shut-downs) over 27 years, and only one was on takeoff (L1011 center engine failed at 2,900 agl after clean up to 250 knots.)
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This thread is cranking up to be quite interesting ...
can lead to quite substantially less thrust than the lowest (climb 2) climb thrust setting
It would be more logical to me, if you wish to use max derate/flex, to continue at that setting until it becomes limiting with respect to climb thrust.
Sadly we do not even get any tables concerning Vmcg/a anymore
You really don't need them per se .. look to the speed schedule tables at minimum weight. Where the speed no longer varies with weight (Vs limiting) you are either Vmca or Vmcg limiting.
when in reality it is a very flexible thing within its limitations.
Basically fixed at very low weights to Vmca limitations, then increases with Vs against weight with the proviso that a modest increase (per overspeed -Boeing, improved performance - AB) for better climb performance usually is available
to keep that speed during rotation and beyond with the kinda lowish rotation speed required for stretched bodylength-aircraft (738/9).
Keeping in mind that V2 is OEI driven.
For the normal AEO takeoff, one isn't looking to peg V2, rather something modestly in excess - typically +15-25 according to AFM recommended practice for twins. Especially for the sports car twins, AEO V2 climb has its own potential for hazard and frightens the daylights out of the new passengers ..
"trained" our new trainers to use 1,000 ft agl Acceleration Altitude everywhere
Common practice to use a standard third segment height for crew familiarity (other than for the nastier places which require specific special escape procedures). Generally, the standard height will be based on the highest runway requirement outside the set of special procedures. eg, in Australia we used (and probably still do) 800ft which was based on Canberra obstacles.
when I see how far behind OEI takeoff flight path navigation
I don't have any problems with cutting down the trapezoid a bit .. with two caveats -
(a) how do we ensure the higher manipulative standard to ensure accurate tracking in the initial OEI phase ?
Plenty of sim studies to show that the reality doesn't match the desire, even with generally high standard of manipulation crews.
It certainly CAN be trained in but that takes time and money. In my experience, one needs a directed sim session's worth of time to achieve a standard where the pilot can reliably back track the opposite localiser from a min weight Vmcg/Vmca limiting takeoff (aft CG .. the full bit) .. but it's wonderful to see the confidence boost once the guy/gal up front gets to that standard. Conversely, most who haven't been exposed to those extremes tend to roll over and go in upside down on the first couple of attempts ...
(b) the aircraft has to have a nav system of sufficent statistical accuracy and reliability to warrant permitting stooging down near and around obstacles
.. with both satisfied all is OK.
I recall my own Damascus .. coming to airline flying as an ops engineer, I had great faith in the engineer's ability to generate wonderful and interesting takeoff and escape data ... the first max weight takeoff in the F27 from a critical length runway ... as I watched (with ever widening eyes) the runway head slide under the radome .. and we were still on the ground .... caused me to adopt a far more conservative approach.
Now that another colleague on this forum is flying rather than computing, I suspect that his views progressively will echo my own ....
My hunch was that TWA's 727-200s with the smallest engine Boeing optioned, would have been more in the arena of net than gross.
That does suggest a bit of over optimistic ops engineering .. the engine Mk should only dictate the numbers for the standardised conditions ...
It still is. 200 feet within the airport boundary, 300 beyond
Then I am glad that I have never worked to 121.
As to accurate information, 1:24,000 topo quads are available for the entire U.S
Having spent much time poring over topos of many and varied scales, and following up with the theodolite slung over the shoulder on numerous occasions .. I don't view anything much worse than 1:5000 - 1:10000 as being other than indicative
So, the crew may want to proceed, for example, to Montrose or Grand Junction rather than returning to Aspen, Eagle, Hayden, Gunnison or Rifle.
Concur .. but mutt's point is that, first, one needs to get high enough to do so. That's where the option of limiting the radius of action (often) provides an advantage.
the end of the takeoff flight path may be too low to turn around
Many of us adopt the practice of running the takeoff calcs up to enroute - certainly OS and I do in the present group. To do otherwise in other than terrain benign environments would be hard to argue successfully in court.
War-story department:
I look forward to an ale or 10 over which the group can exchange a set of similar horror stories.
We just have to accept that the certification data is idealised with few sops to the conscience of reality. On bad hair days, stuff happens to conspire against the crews ... as you observe, systems reliability is a saving grace.
can lead to quite substantially less thrust than the lowest (climb 2) climb thrust setting
It would be more logical to me, if you wish to use max derate/flex, to continue at that setting until it becomes limiting with respect to climb thrust.
Sadly we do not even get any tables concerning Vmcg/a anymore
You really don't need them per se .. look to the speed schedule tables at minimum weight. Where the speed no longer varies with weight (Vs limiting) you are either Vmca or Vmcg limiting.
when in reality it is a very flexible thing within its limitations.
Basically fixed at very low weights to Vmca limitations, then increases with Vs against weight with the proviso that a modest increase (per overspeed -Boeing, improved performance - AB) for better climb performance usually is available
to keep that speed during rotation and beyond with the kinda lowish rotation speed required for stretched bodylength-aircraft (738/9).
Keeping in mind that V2 is OEI driven.
For the normal AEO takeoff, one isn't looking to peg V2, rather something modestly in excess - typically +15-25 according to AFM recommended practice for twins. Especially for the sports car twins, AEO V2 climb has its own potential for hazard and frightens the daylights out of the new passengers ..
"trained" our new trainers to use 1,000 ft agl Acceleration Altitude everywhere
Common practice to use a standard third segment height for crew familiarity (other than for the nastier places which require specific special escape procedures). Generally, the standard height will be based on the highest runway requirement outside the set of special procedures. eg, in Australia we used (and probably still do) 800ft which was based on Canberra obstacles.
when I see how far behind OEI takeoff flight path navigation
I don't have any problems with cutting down the trapezoid a bit .. with two caveats -
(a) how do we ensure the higher manipulative standard to ensure accurate tracking in the initial OEI phase ?
Plenty of sim studies to show that the reality doesn't match the desire, even with generally high standard of manipulation crews.
It certainly CAN be trained in but that takes time and money. In my experience, one needs a directed sim session's worth of time to achieve a standard where the pilot can reliably back track the opposite localiser from a min weight Vmcg/Vmca limiting takeoff (aft CG .. the full bit) .. but it's wonderful to see the confidence boost once the guy/gal up front gets to that standard. Conversely, most who haven't been exposed to those extremes tend to roll over and go in upside down on the first couple of attempts ...
(b) the aircraft has to have a nav system of sufficent statistical accuracy and reliability to warrant permitting stooging down near and around obstacles
.. with both satisfied all is OK.
I recall my own Damascus .. coming to airline flying as an ops engineer, I had great faith in the engineer's ability to generate wonderful and interesting takeoff and escape data ... the first max weight takeoff in the F27 from a critical length runway ... as I watched (with ever widening eyes) the runway head slide under the radome .. and we were still on the ground .... caused me to adopt a far more conservative approach.
Now that another colleague on this forum is flying rather than computing, I suspect that his views progressively will echo my own ....
My hunch was that TWA's 727-200s with the smallest engine Boeing optioned, would have been more in the arena of net than gross.
That does suggest a bit of over optimistic ops engineering .. the engine Mk should only dictate the numbers for the standardised conditions ...
It still is. 200 feet within the airport boundary, 300 beyond
Then I am glad that I have never worked to 121.
As to accurate information, 1:24,000 topo quads are available for the entire U.S
Having spent much time poring over topos of many and varied scales, and following up with the theodolite slung over the shoulder on numerous occasions .. I don't view anything much worse than 1:5000 - 1:10000 as being other than indicative
So, the crew may want to proceed, for example, to Montrose or Grand Junction rather than returning to Aspen, Eagle, Hayden, Gunnison or Rifle.
Concur .. but mutt's point is that, first, one needs to get high enough to do so. That's where the option of limiting the radius of action (often) provides an advantage.
the end of the takeoff flight path may be too low to turn around
Many of us adopt the practice of running the takeoff calcs up to enroute - certainly OS and I do in the present group. To do otherwise in other than terrain benign environments would be hard to argue successfully in court.
War-story department:
I look forward to an ale or 10 over which the group can exchange a set of similar horror stories.
We just have to accept that the certification data is idealised with few sops to the conscience of reality. On bad hair days, stuff happens to conspire against the crews ... as you observe, systems reliability is a saving grace.
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That's why the perf engineers get paid to do what they do, and why they discuss the niceities of it so often - it's not simply deterministic, and can be quite a convoluted story in reality.
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it's not simply deterministic, and can be quite a convoluted story in reality.
.. especially if one doesn't have a nice OEM package and has to work out what the AFM really is trying to do .. all the while keeping an eye to the frozen design standards relevant to the Type ... it does have its moments.
.. especially if one doesn't have a nice OEM package and has to work out what the AFM really is trying to do .. all the while keeping an eye to the frozen design standards relevant to the Type ... it does have its moments.
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j t:
Well, with the modern birds that you see populating the fleet, there are a fair number with triple IRUs, dual GPS sensors, dual (or triple) FMSes, and dual auto-flight. These are the type of aircraft than can (and are often certified for RNP AR values of 0.11 if not 0.10.).
RNP AR requires 2 X the RNP value, but for OEI purposes it could be 1 X RNP. The trapezoid would splay from the DER to the 1 X RNP value. The OEI flight path would be database driven and would have RF legs (limited to 15 degrees of bank, or less) for any track changes.
That would be the real magic from today's high-end technology.
I don't have any problems with cutting down the trapezoid a bit .. with two caveats -
(a) how do we ensure the higher manipulative standard to ensure accurate tracking in the initial OEI phase ?
Plenty of sim studies to show that the reality doesn't match the desire, even with generally high standard of manipulation crews.
(a) how do we ensure the higher manipulative standard to ensure accurate tracking in the initial OEI phase ?
Plenty of sim studies to show that the reality doesn't match the desire, even with generally high standard of manipulation crews.
RNP AR requires 2 X the RNP value, but for OEI purposes it could be 1 X RNP. The trapezoid would splay from the DER to the 1 X RNP value. The OEI flight path would be database driven and would have RF legs (limited to 15 degrees of bank, or less) for any track changes.
That would be the real magic from today's high-end technology.
Moderator
there are a fair number with triple IRUs, dual GPS sensors, dual (or triple) FMSes, and dual auto-flight
No problem with any of that for the latter stages of takeoff, enroute and landing .... JBs have always impressed the daylights out of us all and I'm not immune to gee whiz stuff any more than the next fellow.
However, how do we effect the transition from manual flight to autoflight during the early takeoff stage in a manner which doesn't see the manual bit go outside whatever shape/dimension the trapezoid may be in a critical case with, shall we say, average pilots rather than those who might qualify for "Ace of the Base" brevets ?
No problem with any of that for the latter stages of takeoff, enroute and landing .... JBs have always impressed the daylights out of us all and I'm not immune to gee whiz stuff any more than the next fellow.
However, how do we effect the transition from manual flight to autoflight during the early takeoff stage in a manner which doesn't see the manual bit go outside whatever shape/dimension the trapezoid may be in a critical case with, shall we say, average pilots rather than those who might qualify for "Ace of the Base" brevets ?
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Scientist,JT
V2 min is based on 1.1VMCA or 1.23 VS whichever is higher right?
JT when you mentioned that one could find out whether VMCA/G limited by checking the 'the speed no longer varies with weight (Vs limiting)'.
Are you talking about the Perf tables where you get the ASSUM temp?or the tables in the FCOM where you get the speeds for the actual weight(balanced field)?
Quote:'That's why the perf engineers get paid to do what they do, and why they discuss the niceities of it so often - it's not simply deterministic, and can be quite a convoluted story in reality.'Unquote
I am getting lost, could you please use a more basic english?and I would love to be able and follow this very interesting debate with my ICAO 5.8
Thanks!
V2 min is based on 1.1VMCA or 1.23 VS whichever is higher right?
JT when you mentioned that one could find out whether VMCA/G limited by checking the 'the speed no longer varies with weight (Vs limiting)'.
Are you talking about the Perf tables where you get the ASSUM temp?or the tables in the FCOM where you get the speeds for the actual weight(balanced field)?
Quote:'That's why the perf engineers get paid to do what they do, and why they discuss the niceities of it so often - it's not simply deterministic, and can be quite a convoluted story in reality.'Unquote
I am getting lost, could you please use a more basic english?and I would love to be able and follow this very interesting debate with my ICAO 5.8
Thanks!
Moderator
V2 min is based on 1.1VMCA or 1.23 VS whichever is higher right?
Variation exists depending on the particular Standard but the general rule applies that the minimum takeoff speed (either V2 or VTOSS) is the greater of a Vmca and Vs factor.
JT when you mentioned that one could find out whether VMCA/G limited by checking the 'the speed no longer varies with weight (Vs limiting)'.
Are you talking about the Perf tables where you get the ASSUM temp?or the tables in the FCOM where you get the speeds for the actual weight(balanced field)?
You're looking for a table which gives V1/VR/V2 against RTOW. At the lower weights, for most aircraft, Vmca or Vmcg will become limiting rather than Vs. You see this change when the speed no longer gets lower with reducing weight.
I am getting lost, could you please use a more basic english?
Any time we talk too much jargon and you don't understand, the fault is with us, not you. Just ask and we will try again and rephrase the discussion.
it's not simply deterministic, and can be quite a convoluted story in reality
MFS' meaning here is that it is not just a matter of looking up a table to get the answer. For the RTOW calculation one has to run a series of calculations to check a range of limitations with the most limiting (ie lowest RTOW answer) becoming the final RTOW for the conditions. That process, depending on the aircraft, the runway, and how much effort one wants to put into optimising the result (getting the highest RTOW) can get quite involved and complicated (convoluted)
Variation exists depending on the particular Standard but the general rule applies that the minimum takeoff speed (either V2 or VTOSS) is the greater of a Vmca and Vs factor.
JT when you mentioned that one could find out whether VMCA/G limited by checking the 'the speed no longer varies with weight (Vs limiting)'.
Are you talking about the Perf tables where you get the ASSUM temp?or the tables in the FCOM where you get the speeds for the actual weight(balanced field)?
You're looking for a table which gives V1/VR/V2 against RTOW. At the lower weights, for most aircraft, Vmca or Vmcg will become limiting rather than Vs. You see this change when the speed no longer gets lower with reducing weight.
I am getting lost, could you please use a more basic english?
Any time we talk too much jargon and you don't understand, the fault is with us, not you. Just ask and we will try again and rephrase the discussion.
it's not simply deterministic, and can be quite a convoluted story in reality
MFS' meaning here is that it is not just a matter of looking up a table to get the answer. For the RTOW calculation one has to run a series of calculations to check a range of limitations with the most limiting (ie lowest RTOW answer) becoming the final RTOW for the conditions. That process, depending on the aircraft, the runway, and how much effort one wants to put into optimising the result (getting the highest RTOW) can get quite involved and complicated (convoluted)
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can lead to quite substantially less thrust than the lowest (climb 2) climb thrust setting
It would be more logical to me, if you wish to use max derate/flex, to continue at that setting until it becomes limiting with respect to climb thrust.
It would be more logical to me, if you wish to use max derate/flex, to continue at that setting until it becomes limiting with respect to climb thrust.
Sadly we do not even get any tables concerning Vmcg/a anymore
You really don't need them per se .. look to the speed schedule tables at minimum weight. Where the speed no longer varies with weight (Vs limiting) you are either Vmca or Vmcg limiting.
You really don't need them per se .. look to the speed schedule tables at minimum weight. Where the speed no longer varies with weight (Vs limiting) you are either Vmca or Vmcg limiting.
when in reality it is a very flexible thing within its limitations.
Basically fixed at very low weights to Vmca limitations, then increases with Vs against weight with the proviso that a modest increase (per overspeed -Boeing, improved performance - AB) for better climb performance usually is available
Basically fixed at very low weights to Vmca limitations, then increases with Vs against weight with the proviso that a modest increase (per overspeed -Boeing, improved performance - AB) for better climb performance usually is available
Keeping in mind that V2 is OEI driven.
For the normal AEO takeoff, one isn't looking to peg V2, rather something modestly in excess - typically +15-25 according to AFM recommended practice for twins. Especially for the sports car twins, AEO V2 climb has its own potential for hazard and frightens the daylights out of the new passengers ..
For the normal AEO takeoff, one isn't looking to peg V2, rather something modestly in excess - typically +15-25 according to AFM recommended practice for twins. Especially for the sports car twins, AEO V2 climb has its own potential for hazard and frightens the daylights out of the new passengers ..
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Arba,
please reread my post#60.
ETP designed to be flown at not more than V2 due to obstacles/noise when being in a light,aft CG aircraft and having to turn on the side of the failed engine and not banking 3-5 degrees away from the bad engine,with also spoiler turn assist on 737s can lead your aircraft to become uncontrollable and leading to a disaster.
VMCA was determined using bank into the good engine,using the boeing technique of using rudder to get the control column in the neutral position(bank) does not satisfy the requirement of maintaining a demonstrated VMCA in case of a minimum V2 take off.
Therefore the possibility of losing control.
please reread my post#60.
ETP designed to be flown at not more than V2 due to obstacles/noise when being in a light,aft CG aircraft and having to turn on the side of the failed engine and not banking 3-5 degrees away from the bad engine,with also spoiler turn assist on 737s can lead your aircraft to become uncontrollable and leading to a disaster.
VMCA was determined using bank into the good engine,using the boeing technique of using rudder to get the control column in the neutral position(bank) does not satisfy the requirement of maintaining a demonstrated VMCA in case of a minimum V2 take off.
Therefore the possibility of losing control.
Moderator
Well, no speed schedule tables either
If your software permits playing a bit, try running a series of calculations for reducing weights down to the APS typical weight. You will probably see the effect towards the lower weight end in the output.
you can end up using all of that runway
While some operators do this .. you can also limit the optimisation to give you a pad. For instance, you could use data for an intersection but actually takeoff from an earlier entry point or limit the flex temperature. If you have more user flexibility in a particular program, you probably can limit arbitrarily the runway lengths to provide whatever pad you choose. Talking what ifs here, of course .. operator SOP probably limits your real world flexibility.
i would be interested to see someone peg a V2 that is only 2 kts higher than Vr
Using the OEM AFM techniques, you should be able to peg the AFM recommended V2 OEI without too much difficulty. The VR/V2 relationship includes consideration of the speed increase OEI. If you have a failure prior to VR you should expect to end up someone near V2 towards the end of the rotation sequence. If the rotation is AEO and then you have a failure in the initial climb, you would normally expect to see an AEO speed overshoot (+20-25 being typical). You would then prefer to hold the overspeed to take advantage of the improved climb ... the AEO bit will have put you above the OEI profile so all should be well. My comments may not apply to specific aircraft but will be fairly general in application.
does not satisfy the requirement of maintaining a demonstrated VMCA in case of a minimum V2 take off.
Given that you won't know the precise details of what the certification flight test folks did, you can only work on the basis of what's in the AFM guidance material. If you comply with that guidance, you can presume that the OEM has considered all relevant matters including turns and Vmc effects.
If your software permits playing a bit, try running a series of calculations for reducing weights down to the APS typical weight. You will probably see the effect towards the lower weight end in the output.
you can end up using all of that runway
While some operators do this .. you can also limit the optimisation to give you a pad. For instance, you could use data for an intersection but actually takeoff from an earlier entry point or limit the flex temperature. If you have more user flexibility in a particular program, you probably can limit arbitrarily the runway lengths to provide whatever pad you choose. Talking what ifs here, of course .. operator SOP probably limits your real world flexibility.
i would be interested to see someone peg a V2 that is only 2 kts higher than Vr
Using the OEM AFM techniques, you should be able to peg the AFM recommended V2 OEI without too much difficulty. The VR/V2 relationship includes consideration of the speed increase OEI. If you have a failure prior to VR you should expect to end up someone near V2 towards the end of the rotation sequence. If the rotation is AEO and then you have a failure in the initial climb, you would normally expect to see an AEO speed overshoot (+20-25 being typical). You would then prefer to hold the overspeed to take advantage of the improved climb ... the AEO bit will have put you above the OEI profile so all should be well. My comments may not apply to specific aircraft but will be fairly general in application.
does not satisfy the requirement of maintaining a demonstrated VMCA in case of a minimum V2 take off.
Given that you won't know the precise details of what the certification flight test folks did, you can only work on the basis of what's in the AFM guidance material. If you comply with that guidance, you can presume that the OEM has considered all relevant matters including turns and Vmc effects.
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j_t:
No doubt we have seen that to be such a serious problem in normal ops that, in some cases, RNAV SIDS have been cancelled by the FAA at some major air carrier airports because of the variance in LNAV capture capabilities and pilot fat thumbs.
But, with an RNP AR capable airplane the transition should be smooth and comparatively easy, with LNAV track already being computed by the FMS and ready for engagement either to the FD and/or autoflight. And, if the aircraft has auto-rudder it's no different than the early stages of any liftoff after completion of the takeoff roll.
OTOH, if the pilot has to input rudder manually, and cannot remain within the splay from the DER to the linear RNP containment area then we have some pilot skills that are unsatisfactory. I have that concern today about circumstances where pilots have to perform in "unusual" situations other than just OEI just after V1.
My premise is taking full advantage (touted earlier in this thread) of the state-of-the-art technology on more than a few airframes today. For example, with such technology an OEI containment route can be developed for Aspen Runway 33 that is devoid of rising terrain until almost to Glenwood Springs. (some 27 OEI flight-path miles.)
However, how do we effect the transition from manual flight to autoflight during the early takeoff stage in a manner which doesn't see the manual bit go outside whatever shape/dimension the trapezoid may be in a critical case with, shall we say, average pilots rather than those who might qualify for "Ace of the Base" brevets ?
But, with an RNP AR capable airplane the transition should be smooth and comparatively easy, with LNAV track already being computed by the FMS and ready for engagement either to the FD and/or autoflight. And, if the aircraft has auto-rudder it's no different than the early stages of any liftoff after completion of the takeoff roll.
OTOH, if the pilot has to input rudder manually, and cannot remain within the splay from the DER to the linear RNP containment area then we have some pilot skills that are unsatisfactory.
I have that concern today about circumstances where pilots have to perform in "unusual" situations other than just OEI just after V1.My premise is taking full advantage (touted earlier in this thread) of the state-of-the-art technology on more than a few airframes today. For example, with such technology an OEI containment route can be developed for Aspen Runway 33 that is devoid of rising terrain until almost to Glenwood Springs. (some 27 OEI flight-path miles.)
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Then we concur in respect of the critical problem .. the initial bit.
My observations in the sim in a previous life suggest that there is a BIG need for a LOT of training work to be done before we put aircraft at risk in a reduced obstacle trapezoid scenario ? I have no doubt that just about any half competent pilot can be trained to have a high probability of containment in critical cases ... I just have a concern that the operators won't want to spend the money and effort in the absence of a lot more control by the Regulators.
My observations in the sim in a previous life suggest that there is a BIG need for a LOT of training work to be done before we put aircraft at risk in a reduced obstacle trapezoid scenario ? I have no doubt that just about any half competent pilot can be trained to have a high probability of containment in critical cases ... I just have a concern that the operators won't want to spend the money and effort in the absence of a lot more control by the Regulators.
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j_t:
We concur except for the state-of-the-art birds that track LNAV while rolling and are ready to engage runway track on lift off and then have easily available the OEI procedure (which should be the same as the operator's normal all-engines-operating obstacle departure procedure at an airport like Aspen).
In any case, it is a bad airport, indeed, that has that type of close-in obstacle environment just beyond 300 feet each side of the DER. Even nasty Aspen has no threat until approximately 900 feet to the left of the extended runway centerline close-in.
Then we concur in respect of the critical problem .. the initial bit.
My observations in the sim in a previous life suggest that there is a BIG need for a LOT of training work to be done before we put aircraft at risk in a reduced obstacle trapezoid scenario ? I have no doubt that just about any half competent pilot can be trained to have a high probability of containment in critical cases ... I just have a concern that the operators won't want to spend the money and effort in the absence of a lot more control by the Regulators.
My observations in the sim in a previous life suggest that there is a BIG need for a LOT of training work to be done before we put aircraft at risk in a reduced obstacle trapezoid scenario ? I have no doubt that just about any half competent pilot can be trained to have a high probability of containment in critical cases ... I just have a concern that the operators won't want to spend the money and effort in the absence of a lot more control by the Regulators.
In any case, it is a bad airport, indeed, that has that type of close-in obstacle environment just beyond 300 feet each side of the DER. Even nasty Aspen has no threat until approximately 900 feet to the left of the extended runway centerline close-in.