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Aspen ODP question
I have a question about the ceiling and visibility minima as
alternates for climb gradients in departure procedures. A good example is at Aspen (KASE), straight out of the FAA Instrument Procedures Handbook, but they don't explain the portion I find difficult to understand. I've duplicated the entire text of the procedure at the bottom of this message. So the issue I have is that the required ceiling to avoid the 460 ft/ nm gradient is 3100 feet. That makes an MSL altitude of just under 11,000 feet as the minimum for the bases of the clouds. But, if the clouds are lower, the 460 ft/nm gradient is to be maintained all the way to 14,000 feet MSL. So are all the obstacles below the 11,000 foot ceiling, or not? If not, how can the 3100-3 minimums with standard climb gradient result in a safe operation? Conversely, if all the obstacles penetrating the 40:1 surface are indeed below 11,000 feet, then why require the 460 ft/ nm gradient all the way to 14000 feet? I understand that there will be some obstacle clearance provided by the gradient, whereas the ceiling can be right on the obstacle, but 3000 feet of difference between the two seems too much for that explanation. The old TERPS (in paragraph 1208) stated that "The ceiling value shall be the 100-foot increment above the controlling obstacle or above the altitude required over a specified point from which a 40:1 gradient will clear the obstacle." What does the second part, after the "or," mean? And does that have anything to do with the Aspen procedure? I believe that the newest revision of the TERPS has deleted that second part and added the description of a visual-climb-over-the-airport procedure. Is that supposed to be a replacement with different terminology, or are those two things not related? ASPEN-PITKIN COUNTY/SARDY FIELD TAKE-OFF MINIMUMS: Rwy 15, NA. Rwy 33, 3100-3 or 1000-2 with a min. climb of 460' per NM to 14000. DEPARTURE PROCEDU Climb heading 340° to 8700, then climbing left turn to 16000 heading 270° to intercept and proceed via I-PKN northwest course outbound on backcourse and DBL R-244 outbound to GLENO Int/DBL 22.7 DME. Climb in GLENO holding pattern (SW, left turns, 064° inbound) to cross GLENO at 16000 before proceeding in route. NOTE: Rwy 33, 8179' tree 3447' from departure end of runway, 1379' left of centerline. The IPH also has an example of the visual-climb-over-the-airport procedure, which is very explicitly stated as part of the ODP: BECKWOURTH, CA NERVINO TAKE-OFF MINIMUMS: Rwys 7, 25, 3500-3 for climb in visual conditions. DEPARTURE PROCEDU Rwys 7, 25, for climb in visual conditions: cross Nervino Airport at or above 8300 before proceeding on course. thanks, Peter |
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Aspen ODP question
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#3
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Aspen ODP question
Correction: "VOA" should be "VCOA"
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#4
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Aspen ODP question
That's quite troubling. Is it true that with the new TERPS criteria,
the Aspen departure procedure would have been written differently, or is teleportation still going to be implied in newly-developed procedures? Why don't they set the ceiling to be above all the obstacles as is implied in all the text books I've looked at? The books (including the FAA IFH and IPH) say that you should avoid obstacles visually along the departure, without mentioning that you have to somehow cross back over the airport. On Oct 24, 7:13 am, Bee wrote: Visual Climb Overairport (VOA) is a fairly recent implementation to TERPS criteria and simply does not lend itself to application at airports with very close in terrain. Aspen does NOT have a VOA. The ceiling and visibility is simply a facade. All it means is that if you were somehow able to cross the departure end of Runway 33 at 3100 feet, agl, you would now be 40:1 clear along the departure path. Some FAA suits claim it enables you to avoid obstacles on a "progressive" basis until leaving 10,920 msl. That, of course, is field full of meadow muffins. Moral: If you can't make good the climb gradient, you have your hands full of crap. |
#5
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Aspen ODP question
A normal IDP requires 152 ft/nm, about 350 ft. min @ 120
KIAS. Many airports have obstacles that require a steeper climb, so they publish "non-standard TO minima" Some airports cannot be departed safely in IMC due to local terrain. Altitudes required to clear an obstruction include a margin, 2,000 feet in mountainous regions and 1,000 feet in other areas. The IDP gradient at Aspen is based on the angle from the departure end to the critical obstacle, a rate that is well above the engine-out performance of most airplanes. [460 ft/nm will be close to 1,000 ft/min and most turboprops won't do that on one engine, it is the worst your plane can do that is the performance you need to consider.] Once past the critical obstacle, a climb at standard rates will be safe. [Again, those rates may be above the performance of many smaller, low powered aircraft.] The ideal airplane for Aspen is probably an F15-F22 class fighter, go vertical to FL 240. But most pilots don't fly with that much power. Aspen is a dangerous place for the unprepared and a wonderful place for those who know how to fly in the mountains, when to fly and have the equipment and stay within the limits. wrote in message oups.com... I have a question about the ceiling and visibility minima as alternates for climb gradients in departure procedures. A good example is at Aspen (KASE), straight out of the FAA Instrument Procedures Handbook, but they don't explain the portion I find difficult to understand. I've duplicated the entire text of the procedure at the bottom of this message. So the issue I have is that the required ceiling to avoid the 460 ft/ nm gradient is 3100 feet. That makes an MSL altitude of just under 11,000 feet as the minimum for the bases of the clouds. But, if the clouds are lower, the 460 ft/nm gradient is to be maintained all the way to 14,000 feet MSL. So are all the obstacles below the 11,000 foot ceiling, or not? If not, how can the 3100-3 minimums with standard climb gradient result in a safe operation? Conversely, if all the obstacles penetrating the 40:1 surface are indeed below 11,000 feet, then why require the 460 ft/ nm gradient all the way to 14000 feet? I understand that there will be some obstacle clearance provided by the gradient, whereas the ceiling can be right on the obstacle, but 3000 feet of difference between the two seems too much for that explanation. The old TERPS (in paragraph 1208) stated that "The ceiling value shall be the 100-foot increment above the controlling obstacle or above the altitude required over a specified point from which a 40:1 gradient will clear the obstacle." What does the second part, after the "or," mean? And does that have anything to do with the Aspen procedure? I believe that the newest revision of the TERPS has deleted that second part and added the description of a visual-climb-over-the-airport procedure. Is that supposed to be a replacement with different terminology, or are those two things not related? ASPEN-PITKIN COUNTY/SARDY FIELD TAKE-OFF MINIMUMS: Rwy 15, NA. Rwy 33, 3100-3 or 1000-2 with a min. climb of 460' per NM to 14000. DEPARTURE PROCEDU Climb heading 340° to 8700, then climbing left turn to 16000 heading 270° to intercept and proceed via I-PKN northwest course outbound on backcourse and DBL R-244 outbound to GLENO Int/DBL 22.7 DME. Climb in GLENO holding pattern (SW, left turns, 064° inbound) to cross GLENO at 16000 before proceeding in route. NOTE: Rwy 33, 8179' tree 3447' from departure end of runway, 1379' left of centerline. The IPH also has an example of the visual-climb-over-the-airport procedure, which is very explicitly stated as part of the ODP: BECKWOURTH, CA NERVINO TAKE-OFF MINIMUMS: Rwys 7, 25, 3500-3 for climb in visual conditions. DEPARTURE PROCEDU Rwys 7, 25, for climb in visual conditions: cross Nervino Airport at or above 8300 before proceeding on course. thanks, Peter |
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Aspen ODP question
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#7
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Aspen ODP question
Jim Macklin wrote:
A normal IDP requires 152 ft/nm, about 350 ft. min @ 120 KIAS. Many airports have obstacles that require a steeper climb, so they publish "non-standard TO minima" Some airports cannot be departed safely in IMC due to local terrain. Altitudes required to clear an obstruction include a margin, 2,000 feet in mountainous regions and 1,000 feet in other areas. The IDP gradient at Aspen is based on the angle from the departure end to the critical obstacle, a rate that is well above the engine-out performance of most airplanes. [460 ft/nm will be close to 1,000 ft/min and most turboprops won't do that on one engine, it is the worst your plane can do that is the performance you need to consider.] Once past the critical obstacle, a climb at standard rates will be safe. [Again, those rates may be above the performance of many smaller, low powered aircraft.] From AC 120-91: 7. TERPS CRITERIA VERSUS ONE-ENGINE-INOPERATIVE REQUIREMENTS. a. Standard Instrument Departures (SID) or Departure Procedures (DP) based on TERPS or ICAO Procedures for Air Navigation Services—Aircraft Operations (PANS-OPS) are based on normal (all engines operating) operations. Thus, one-engine-inoperative obstacle clearance requirements and the all-engines-operating TERPS requirements are independent, and one-engine-inoperative procedures do not need to meet TERPS requirements. Further, compliance with TERPS all-engines-operating climb gradient requirements does not necessarily assure that one-engine-inoperative obstacle clearance requirements are met. TERPS typically use specified all-engines-operating climb gradients to an altitude, rather than certificated one-engine-inoperative airplane performance. TERPS typically assume a climb gradient of 200 feet per nautical mile (NM) unless a greater gradient is specified. For the purposes of analyzing performance on procedures developed under TERPS or PANS-OPS, it is understood that any gradient requirement, specified or unspecified, will be treated as a plane which must not be penetrated from above until reaching the stated height, rather than as a gradient which must be exceeded at all points in the path. Operators must comply with 14 CFR requirements for the development of takeoff performance data and procedures. There are differences between TERPS and one-engine-inoperative criteria, including the lateral and vertical obstacle clearance requirements. An engine failure during takeoff is a non-normal condition, and therefore takes precedence over noise abatement, air traffic, SIDs, DPs, and other normal operating considerations. |
#8
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Aspen ODP question
Yes, I know that no FAA lawyer dies when a aircraft has a
CFIT during an IDP after an engine failure. Any competent pilot will consider such "details" and adjust gross weight, weather or other parameters because pilots [and passengers] die, not FAA lawyer. "Bee" wrote in message ... | Jim Macklin wrote: | A normal IDP requires 152 ft/nm, about 350 ft. min @ 120 | KIAS. | Many airports have obstacles that require a steeper climb, | so they publish "non-standard TO minima" | Some airports cannot be departed safely in IMC due to local | terrain. | Altitudes required to clear an obstruction include a margin, | 2,000 feet in mountainous regions and 1,000 feet in other | areas. | The IDP gradient at Aspen is based on the angle from the | departure end to the critical obstacle, a rate that is well | above the engine-out performance of most airplanes. [460 | ft/nm will be close to 1,000 ft/min and most turboprops | won't do that on one engine, it is the worst your plane can | do that is the performance you need to consider.] | Once past the critical obstacle, a climb at standard rates | will be safe. [Again, those rates may be above the | performance of many smaller, low powered aircraft.] | | From AC 120-91: | | 7. TERPS CRITERIA VERSUS ONE-ENGINE-INOPERATIVE REQUIREMENTS. | | a. Standard Instrument Departures (SID) or Departure Procedures (DP) | based on TERPS or ICAO Procedures for Air Navigation Services—Aircraft | Operations (PANS-OPS) are based on normal (all engines operating) | operations. Thus, one-engine-inoperative obstacle clearance requirements | and the all-engines-operating TERPS requirements are independent, and | one-engine-inoperative procedures do not need to meet TERPS | requirements. Further, compliance with TERPS all-engines-operating climb | gradient requirements does not necessarily assure that | one-engine-inoperative obstacle clearance requirements are met. TERPS | typically use specified all-engines-operating climb gradients to an | altitude, rather than certificated one-engine-inoperative airplane | performance. TERPS typically assume a climb gradient of 200 feet per | nautical mile (NM) unless a greater gradient is specified. For the | purposes of analyzing performance on procedures developed under TERPS or | PANS-OPS, it is understood that any gradient requirement, specified or | unspecified, will be treated as a plane which must not be penetrated | from above until reaching the stated height, rather than as a gradient | which must be exceeded at all points in the path. Operators must comply | with 14 CFR requirements for the development of takeoff performance data | and procedures. There are differences between TERPS and | one-engine-inoperative criteria, including the lateral and vertical | obstacle clearance requirements. An engine failure during takeoff is a | non-normal condition, and therefore takes precedence over noise | abatement, air traffic, SIDs, DPs, and other normal operating | considerations. |
#9
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Aspen ODP question
Jim Macklin wrote:
Yes, I know that no FAA lawyer dies when a aircraft has a CFIT during an IDP after an engine failure. Any competent pilot will consider such "details" and adjust gross weight, weather or other parameters because pilots [and passengers] die, not FAA lawyer. If you are implying that some FAA lawyer wrote that language, you have it wrong. That advisory circular was written by some pretty sharp FAA ops folks who are trying to inform a misinformed aviation community. |
#10
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Aspen ODP question
The sharp people at the FAA write, the lawyers edit.
The FAA will allow pilots to kill themselves in Part 91 operations, they tighten up under 121,135 commercial ops. Me, I want to have lots of room under the belly. The 300 King Air climbs well on one engine, particularly when the weight is less than 14,000 lbs. TOW. But a 90 series King Air or even a 200, is under powered at high and hot airports. It is my policy to be able to se and avoid, or fly IFR with margins even beyond the word in the law. "Bee" wrote in message ... | Jim Macklin wrote: | Yes, I know that no FAA lawyer dies when a aircraft has a | CFIT during an IDP after an engine failure. | | Any competent pilot will consider such "details" and adjust | gross weight, weather or other parameters because pilots | [and passengers] die, not FAA lawyer. | | | If you are implying that some FAA lawyer wrote that language, you have | it wrong. That advisory circular was written by some pretty sharp FAA | ops folks who are trying to inform a misinformed aviation community. |
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