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Aspen Slope 2% ???

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Jul 10, 2004
Are most aircraft limited to 2% up and -1% down for take off and landing and if so how do you legally get out of Aspen. The aircraft we fly is 2% up -1% so we don,t even have balanced field for this runway. Now it has been my understanding is that the AFM does not have for performance for any particular operation then it is not legal. Any help on this would be great
i like the philosophy of a chief pilot i once had the priviledge of working with:

"we don't go into airports where the elevation exceeds the length of the runway."

it worked for many years until he retired, which was a sad day for many of us. i go into kase with regularity now. :)
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As I recall KASE is a 2% slope... The difference between the ends of the runway are 140' (if I remember right) and the length is 7000. Which gives you a 2% slope. What aircraft are you flying? What is limiting you getting out of there legally?? BFL??? Take less weight... Leave there and get gas somewhere else... Second seg climb gradient is usually what gets most people... For the departure (someone correct me if Im wrong) it takes about a 460' per NM which is over a 7% climb grad... Depending on temp and stuff like that, alot of aiplanes cant do that... Unless your in a Falcon 50EX/900, Gulfstream or Lear 60. Work the charts and see what you can really do... The tab data in a checklist can be very limiting...
we fly a westwind which only has numbers for 2% up -1% down. In the AFM it states 1% down is not the limit but there are no performance charts for anything more than -1%. So can we take off ???
Falcon 2000 & 2000EX +/- 2%
falconpilot said:
For the departure (someone correct me if Im wrong) it takes about a 460' per NM which is over a 7% climb grad... Depending on temp and stuff like that, alot of airplanes can't do that...
You aren't required to be able to fly the departure procedure gradients with an engine out - it's strictly a "normal" (all engines operating) requirement. At Aspen, you have to take a hard look at both 2nd segment and approach climb requirements.

Lead Sled said:
You aren't required to be able to fly the departure procedure gradients with an engine out - it's strictly a "normal" (all engines operating) requirement. At Aspen, you have to take a hard look at both 2nd segment and approach climb requirements.


Under 135/121 you are required to use the charts provided by the manufacturer. And they are not required to provide any take-off climb charts except engine out. And they do not. The problem with Part 91, is that if anything happens you will have to prove that you met the climb requirements. So prove it. There is another option under Part 135/121. That is an alternate procedure. Used to do it with the CV580 into ASE. If you lost one on takeoff, just past the runway end, you did a 80 degree turn to the right then a 260 degree turn to the left. That will have you aimed at the end of the runway. An interesting manuver all the same.

Either way, ASE is not an airport for tghe inexperienced or uninformed.
There have been some recent threads on this very subject in the recent past. To save some typing time (I'm heading our for the beach.) I'll cut and paste a response that I gave in a recent thread.


This whole topic is perhaps one of the most misunderstood aspects encountered when you transition into flying jets. Let me try to explain it the best I can.

Second segment climb is part of a certification requirement under FAR 25 (Sec. 25.121 Climb: One-engine-inoperative). In each "phase" of the takeoff, takeoff-gear down, takeoff-gear up, and takeoff-final, a Part 25 transport category aircraft must exhibit a minimum one-engine inoperative climb gradient (rise/run) except for those phases that involve level acceleration.

These phases or segments must be specified by clearly defined changes of configuration, thrust, & speed. They begin from lift off and continue until the aircraft is at least 1,500 feet above the runway elevation or to point where transition to the enroute configuration is complete (clean, MCT thrust, 1.25 Vs). This is known as the "Takeoff Path" of the aircraft.

The gradient of climb is depended on the number of engines installed, giving greater safety margins to those aircraft with more engines (the idea is more engines means a heavy, less maneuverable aircraft, and thus should have greater minimum climb requirements) For a two-engine transport category aircraft, the 1st segment (lift-off to gear retraction) requires a positive gradient out of ground effect. A 2.4% gradient is required from gear retraction to 400 ft. in the takeoff configuration, gear up, takeoff thrust, at V2. At the end of the final segment, clean, MCT, 1.25 Vs (otherwise known as "enroute configuration"), the aircraft must capable of a 1.2% climb.

Both FAA approved Aircraft Flight Manual and the FAR's are going to require the pilot/operator to limit takeoff weight so as to meet this certification requirement. For Part 91 operators of aircraft certified after 9/30/58, it's 91.605(b)(1) and for Part 135 operators it's 135.379(a). There will also be a limitation in the AFM limiting the takeoff weight such that these one engine-out climb requirements are met. Usually it's in the form of a statement such as "the maximum allowable takeoff weight shall not exceed that shown in the takeoff weight limit chart", but that can vary between manufacturers. So you must always meet your 2nd segment climb requirements along with the minimum climb requirements for other segments. Comply with the AFM restrictions and the approprate charts in this matter and you'll be ok.

So far, most everyone gets it correct up to this point. It's when you start Taking obstacle clearance and TERP's requirements that folks tend to get things screwed up. FAR 25.115 defines the takeoff flight path. For each weight, temperature, and pressure altitude the manufacturer must determine the one engine-out takeoff flight path. They must use the same segments as defined in the certification climb requirement above. The takeoff flight path begins at end of the one engine-out takeoff distance (35 feet above the runway or a point known as "reference zero") and continues to the end of the takeoff path described above (1,500 feet or transition to the enroute configuration complete, whichever is higher). This is the actual performance of the aircraft as demonstrated from flight testing based on procedures developed for "in-service" operation, flown by crew's of "average skill", with allowances for any time delays that may be expected in service (25.101).

The net takeoff flight path represents the takeoff flight path described above diminished by a percentage of climb gradient depended on the number of engines installed, -0.8% or two engine aircraft, -0.9% for three engine aircraft, and -1.0% for four engine aircraft. Since both the actual (gross) takeoff flight path and the net takeoff flight path begin at 35 feet, you can see that net flight path will be 0.8% lower (2 engine aircraft with an engine inoperative) than the actual flight path giving a difference of 48' per nautical mile between the two flight paths. The concept here is that the difference between the actual flight path and net flight path yields an ever increasing spread between the two path. At 10 miles, they'll be 480 feet separation between the two flight paths. As you'll see below, obstacle clearance is based on the net flight path to as to ensure an increasing margin for obstacle clearance as the aircraft climbs further from the runway.

The net takeoff flight path is used in meeting the one-engine out takeoff flight path requirements of FAR 121.189(d) and FAR 135.379(d) for turbine aircraft. This regulation states that the net takeoff flight path must clear obstacles by 35 feet for those obstacles 200 feet either side of the flight path inside the airport boundaries and 300 feet either side after passing the airport boundaries. Each operator must perform a detailed analysis of all obstacles, and using either the AFM flight path charts or computer-based performance programs demonstrate that they can meet the above obstacle clearance requirements. Obstacle data is obtained from a variety of sources including airport obstruction charts, USGS terrain charts, etc. It's not something you are going to do on pre-flight. You'll have to obtain this obstacle data from a engineering source like Jeppesen Ops' Data. They'll give you obstacle data for a particular airport/runway and any special engine-out turning procedures that may need to be applied. If Jeppesen Op's Data has the AFM data, they can do all this ahead of time and print out an "Airport Analysis". From this analysis, you have the maximum weight allowable for that airport/runway in terms of a runway limit weight and a climb limit weight for a given temperature. Correction factors are provided for non-standard conditions, wind, A/I on or off, etc. The airport analysis is the method used by the FAR 121 air carriers.

Now, let talk TERP's, DP (a.k.a. SID) and climb performance. First, the one engine-out obstacle clearance requirements stated above and the TERP's IFR obstacle clearance requirements are two entirely different subjects! They are not related in any way. A transport category aircraft suffering an engine failure on takeoff will likely NOT meet TERP's climbs requirements and IS NOT REQUIRED TO DO SO!!!!!!!!!!! (enough emphasis?) This is where folk get things wrong. The AIM alludes to this in 5-2-6(e)(4) by stating that the pilot should "consider the effects of degraded performance and the actions to take in the event of an engine loss during the departure." The Canadian supplement and ICAO PAN-OPS state it more clearly that IFR SID's and departure procedures are based on normal, read all-engine performance, and not one-engine out performance.

TERP's climb requirements for DP's are based on a 40:1 obstacle identification surface (OIS) beginning no higher than 35 above the departure end of runway and continuing to the minimum altitude for enroute operations. If no obstructions penetrate the 40:1 OIS then the standard IFR climb gradient of 200 ft/NM applies. This provides at least 48 feet per nautical mile of obstacle clearance. If obstacles penetrate the OIS, then the DP climb gradient will be raised a sufficient amount to regain the 48 ft/NM clearance. Careful note must be given here. There could be obstacle which would require higher than standard climbs but only to heights less than 200 feet above the runway. In this case, higher than standard climb gradients are NOT provided

The problem with a Part 25 aircraft is that we are not provided with all engine climb performance data in the AFM. When the performance rules were first written for the first jet transport aircraft (SR-422), one engine-out performance was considered more restrictive than all engine performance data. This engine out performance data was used to develop the takeoff flight path concept we discuss above. The climb gradient data from the AFM is used ONLY to construct the net takeoff flight path as described above and cannot be used in meeting TERP's criteria. Any attempt to use the climb gradient charts from a Part 25 AFM in determining TERP's obstacle clearance would be using this data in a manner for which it was never intended and never approved for.

There are several reasons you cannot use AFM 2nd segment climb data in meeting TERP's criteria. First, all the one engine-out climb flight path data (1st, 2nd, and final segment climb charts) are only good to 1,500 above the runway (some manufacturers have gone beyond this point up to 3,000 to 5,000 feet) and CANNOT be used to the heights demanded of certain DP's such as is the case of KASE, 7,800 ft to 14,000 ft. 2nd segment climb data is generally only valid to 400 ft above runway, the point where 2nd segment ends. Second, the differences in climb terminology. Most 2nd segment climb gradient charts in AFM's give the available NET climb gradient so that when you apply this to the flight path charts or computer program you get a resulting NET flight path. TERP's climb requirements are based on actual performance, NOT an already an already reduced NET climb gradient. There's the consideration of 5 minute limitation on takeoff thrust. Many DP's require climb gradients to significantly high altitudes that would exceed the limitation on takeoff thrust, not to mention a shallowing climb gradient due to density altitude changes as you climb. Remember if you try to use 2nd segment climb, you'll only meet that climb gradient if you keep V2, takeoff flaps, and takeoff thrust and that climb gradient is generally valid only at 400 ft above the runway. Finally, as we said above, TERP's performance is stricly considering normal aircraft performance, not an emergency situation such as engine out climb.

Here's some more information from that same thread. That's it, I'm out the door on my way to the beach.


FAR 25.121 does not specify a minimum certification (gross) climb gradient for the enroute configuration beyond 1,500 feet AGL (end of the takeoff path under FAR 25.111). However, FAR 25.123 does require the determination of the one-engine inoperative and two-engine inoperative (for 3-engine or 4-engine aircraft) enroute flight paths. These enroute flight paths must be determined at each weight, temperature, and pressure altitude within the aircraft's operating limits and will have a gradient reduction applied.

Typically, the AFM will state that the net enroute climb gradient chart(s) are presented for pilot reference, FAR 25 requires their inclusion in the AFM for use in determining obstacle clearance for the net enroute flight path as required under FAR 121.191 (one-engine inoperative) & 121.193 (two engine inoperative) or FAR 135.381 (one-engine inoperative) & 135.383 (two engine inoperative).

So the two big questions are as follows:

1. How does one compute climb requirements above 1500 AGL when no data is available from the manufacturer?

The net enroute climb gradient chart(s) will provide you with the available net enroute climb gradient for your current weight, temperature, and pressure altitude. With this information, you can 1) review the entire route and ensure you have a positive net enroute climb gradient clearing all obstacles by 1,000 ft, 5 SM either side of the intended route, or 2) pick the most critical point on the route, assume the engine fails at that point, and continue with a net enroute flight path that clears obstacles by 2,000 ft, 5 SM either side of track. You may assume normal fuel consumption using either method. Using method 2, you must also designate as an alternate airport the airport you use after the engine fails. That airport must meet the required alternate weather minimums. You may break up the route into a series of segments with the most advantageous drift down route and alternate for each segment.

So where do you find the obstacle data for the planned route? United Airlines has a world wide computer obstacle database and dispatch program this purpose. For us, sectional charts, Grid MORA's MEA's, MOCA's, would be good starting points. This is a dispatch function only. If the engine fails, you're still expected to land at the nearest suitable airport.

2. How in the world can any aircraft legally depart Aspen under any circumstances? How does United Express and others flying BAC 146's, Dash 8's, and other commuter aircraft types legally depart from ASE? The BAC 146 might meet the DP if it lost an engine if was going to DEN, but how about to ORD? I doubt it. The Dash 8's and other prop commuters? It's inconceivable to me that they'd meet the DP with an engine out. I just can't see them outperforming a Lear 31A on one engine. These are all FAR 121 air carriers with extensive FAA oversight. Yet they takeoff every day from ASE and in bad weather. The same could be said for other airports like Reno.

The DP is a normal performance procedure only. Even the AIM alludes to this by specifying that the pilot consider the effects of reduced performance following an engine failure on a DP and have alternative actions available.

In answer to this specific question, using a sample airport analysis for ASE runway 33 and for a Lear 35 the climb limit weight at 80 degrees F is 16,030 lbs. This weight limit meets 1st, 2nd, and final segment certification (gross) climb requirements. The runway 33 limit weight is 14,770 lbs. The runway limit weight meets the requirements for takeoff distance (all engine & one engine inoperative), accelerate stop distance, brake energy limit, and net takeoff flight path obstacle clearance utilizing a special engine out departure procedure. This procedure does follow the valley out to a holding pattern on the DBL R-244 at 15.0 DME, essentially in the valley over Carbondale, CO. At this weight, 14.770 lbs., you will not meet the DP climb gradient to 14,000 feet with one engine inoperative. The 2nd segment net gradient about 4%. Still, an FAR 121 or 135 operator of this Lear 35 would be perfectly legal departing Aspen at this weight and temperature, assuming that no other Subpart I dispatch requirements are more restrictive.

Does a 121 or 135 operator have to meet the takeoff minimums? Yes, under 91.175 and this does include the DP climb gradient unless weather conditions allow using the see & avoid method. But the required climb performance is based on normal performance, all engine performance. The same goes for Part 91 operators too, if they accept the DP, but again only with all-engine, normal performance.

The Jeppesen Airport Analysis reports provide escape maneuvers that are not published in any charts we normally carry on the aircraft. In fact, the escape maneuver from Jeppesen at ASE essentially follows the valley out to GJT. Hence the reason for VMC.