Approach Climb Gradient vs EOSID

[FlightPathOBN]

However, compliance with the above is no guarantee that an airplane will be able to extract from an IFR approach simply by flying the (all engines) published missed approach procedure after losing an engine. That calculation is left to the operator and its provider of performance engineering/analysis.

Exactly. Try using the numbers in the AFM at Bangda, Lhasa, or Cuzco.

The AC was published specifically to detail that the missed approach shown on the charts is NOT EO. While you MAY be able to meet the 2.5% requirement, the obstacle clearance surface and ROC is designed for all engine missed.

I am currently designing RNP approaches into Bandga, are you saying I should stick with the AFM climb gradients of 2.5%?.... how 'innovative'

Look at it this way, you are on final airport elevation near 5000, temp 25C, flaps 30 or 40...down to Vref around 140kts, so almost all of your energy is gone, and lose an engine. You now have to get the engine spooled up, all the bleed/icing etc off, balanced and to flaps 1 (the AFM basis for climb)...and not drop below the MDA...and is your climb near 2.5%

[Pugilistic Animus]

However FAR 25 is not an operating regulation -- rather it defines certification standards to Boeing, Embraer, Airbus, etc. Describes minimum flight paths for flight test engineers who are compiling data for AFM.

Yes, but part 121, which is what I've linked, are operating regulations...

Edit you use the lowest of the weights to meet the most restrictive limits as certified and approved by the POI

the minimum missed approach is designed for OEI---if you can't meet that limit you are overweight for the operation and are therefore operating illegally---at least with TERPS the assumption of OEI-missed approach must be built in to the procedure design

[aterpster]

FlightPathOBN:

I am currently designing RNP approaches into Bandga, are you saying I should stick with the AFM climb gradients of 2.5%?.... how 'innovative'

I would say you should stick with FAA Order 8260.52.

Order of priority:

1. First line of minima single-string. Additional lower line of minima up to four total if the criteria increments can be satisfied.

2. Attempt to fit non-RNP missed approach with a climb gradient of 200 feet per mile. If that doesn't work, then next is a non-RNP missed approach with a climb gradient up to 425 feet per mile, if necessary to support lowest possible minimums. If that won't work then an RNP missed approach, and perhaps still with a climb gradient of as much as 425 feet per mile.

Presumably, you are third-party developer. If you are working for a specific operator, presumably they would also want you to develop a OEI procedure. But, if you have had to resort to an RNP missed approach with a climb gradient of 425 feet per mile, or thereabouts, the OEI procedure at such a location could be a tough nut to crack.

Then again, some of the business aircraft that are RNP AR capable can exceed a sustained 425 feet per mile with one engine inoperative at max landing weight, or less. Even though they have to level off to clean up as per the OEI profile, their performance is sufficiently robust that they don't fly into the 425' per mile constant slope. So, it's an easy nut to crack for aircraft like those.

I don't know where Bangda is, but I suspect you may have your hands full satisfying the requisite survey requirements.

[aterpster]

Pugilistic Animus:

at least with TERPS the assumption of OEI-missed approach must be built in to the procedure design.

You might want to recheck your sources on that one.

[Pugilistic Animus]

• Land within the distance required by the regulations.
• Climb from the missed approach point (MAP)
and maintain a specified climb gradient with one
engine inoperative.
• Perform a go-around from the final stage of
landing and maintain a specified climb gradient
with all engines operating and the airplane
in the landing configuration.

Aterpster I would defer to you on those matters however---but if you could please explain what I'm missing here? that isn't the approach climb [missed approach flight path] predicated on a minimum gradient unless special procedures apply

[aterpster]

Pugilistic Animus:

I don't know what document you are quoting, but here is what TERPs says:

201. TERPS. Concept of Primary Required Obstacle Clearance (ROC). The title of this order, United States Standard for Terminal Instrument Procedures (TERPS), contains a key word in defining the order's content. The word is "STANDARD;" something set up and established by authority as a rule for the measure of quantity, weight, extent, value, or quality.

a. The TERPS document specifies the minimum measure of obstacle clearance that is considered by the FAA (the Federal authority) to supply a satisfactory level of vertical protection. The validity of the protection is dependent, in part, on assumed aircraft performance. In the case of TERPS, it is assumed that aircraft will perform within certification requirements.

b. The following is an excerpt from the foreword of this order: "These criteria are predicated on normal aircraft operations for considering obstacle clearance requirements." Normal aircraft operation means all aircraft systems are functioning normally, all required navigational aids (NAVAID's) are performing within flight inspection parameters, and the pilot is conducting instrument operations utilizing instrument procedures based on the TERPS standard to provide ROC. While the application of TERPS criteria indirectly addresses issues of flyability and efficient use of NAVAID's, the major safety contribution is the provision of obstacle clearance standards. This facet of TERPS allows aeronautical navigation in instrument meteorological conditions (IMC) without fear of collision with unseen obstacles. ROC is provided through application of level and sloping OCS.

Also, Paragraph 7 in AC 120-91.

[Pugilistic Animus]

Aterpster
Paragraph 7 seems to be dealing with DP and SIDs...I'm not suggesting that TO OEI flight path is based on following a SID or DP only the approach climb I though a minimum climb gradient over the OCS is specified in the initial design-for OEI approach climb and AEO landing climb-as district from OEI special procedures for TO, perhaps I'm loose with my phrasing...I'm not suggesting following the SID or any other Flight path for obstacle avoidance for EFATO...I'm only referring to the approach climb


sorry, that except is from the 'instrument procedures handbook'...

edit Pprune automatically writes out engine failure on TO for EFATO not me

see EFATO, EFATO, EFATO

[Zeffy]

Pugilistic Animus
From the Instrument Procedures Handbook:

Typically, the AFM for a large turbine powered airplane should contain information that allows flight crews to determine that the airplane will be capable of performing the following actions, considering the airplane’s landing weight and other pertinent environmental factors:
• Land within the distance required by the regulations.
• Climb from the missed approach point (MAP) and maintain a specified climb gradient with one engine inoperative.
• Perform a go-around from the final stage of landing and maintain a specified climb gradient with all engines operating and the airplane in the landing configuration.

One must be mindful that the procedure-specified "gradient" in a missed approach is linear -- compare to a sheet of plywood.

But we know that Transport Airplanes don't climb along a linear path in the real world.

The AFM data for approach climb specify the operative engine(s) at takeoff thrust. There are time limits for takeoff thrust. And we also know that available thrust will be decreasing with altitude as the jet climbs in the clean configuration (enroute and final) with thrust set at max continuous. So the actual climb path will be anything but linear.

An IFR procedure's missed approach may include instructions to "fly runway track to _______MSL, then turn to (heading), intercept _____ radial until leaving______ MSL, then proceed direct_______"

In WAT-limiting conditions, the aircraft may be many, many miles downstream prior to reaching the first turn's altitude, may find itself up against time limitations for the approach climb thrust and may require a transition to enroute and final climb configuration (yet another set charts).

So it's a little simplistic for the Instrument Procedures Handbook to state that "crews can determine that the airplane will be able to maintain a specified climb gradient with one engine inoperative." (paraphrasing)

The key sentence in AC 120-91 paragraph seven may be:

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.

The OEI performance analysis for locations with lengthy and complex missed approach procedures can tax or exceed the skill sets and competence of average cockpit crew. (Such an analysis is certainly beyond my own abilities.)

[HazelNuts39]

I haven't come across an "Instrument Procedures Handbook". I wonder if anyone could enlighten me as to its origin and status. To whom it is addressed? Thanks in advance.

Regards,
HN39

[Pugilistic Animus]

HN39---the IPH is an FAA publication for pilots earning an instrument rating or moving up to more advanced airline procedures

[Zeffy]

Link. FAA Instrument Procedures Handbook

PREFACE
This handbook supercedes FAA-H-8261-1, Instrument Procedures Handbook, dated 2004. It is designed as a technical reference for professional pilots who operate under instrument flight rules (IFR) in the National Airspace System (NAS). It expands on information contained in the FAA-H-8083-15, Instrument Flying Handbook, and introduces advanced information for IFR operations. Instrument flight instructors, instrument pilots, and instrument students will also find this handbook a valuable resource since it is used as a reference for the Airline Transport Pilot and Instrument Knowledge Tests and for the Practical Test Standards. It also provides detailed coverage of instrument charts and procedures including IFR takeoff, departure, en route, arrival, approach, and landing. Safety information covering relevant subjects such as runway incursion, land and hold short operations, controlled flight into terrain, and human factors issues also are included.

[Pugilistic Animus]

Zeffy would not the actual performance be a gross gradient over the obstacle clearance surface? perhaps it's true that a five or 10 minute limits may make a difference, but usually the limit is most severe on a WAT-limited OEI TO procedure---Engineers like Mutt have even discussed the possibity of of Negative climb performnce for the OEI TO climb to 1500 above the airport elevation---

all the pilot can do is assure that the WAT limits for approach climb are legally met

[HazelNuts39]

Thanks Pugilistic Animus;

I understand the IPH is educational rather than regulatory, and find this statement somewhat simplistic:

Typically, the AFM for a large turbine powered airplane should contain information that allows flight crews to determine that the airplane will be capable of performing: (...)
• Climb from the missed approach point (MAP) and maintain a specified climb gradient with one engine inoperative.

FAR 25.1587(b)(3) requires the AFM to provide no more than:

(3) The following performance information (determined by extrapolation and computed for the range of weights between the maximum landing weight and the maximum takeoff weight):

(i) Climb in the landing configuration.

(ii) Climb in the approach configuration.

(iii) Landing distance.

Regards,
HN39

[aterpster]

HazelNuts39:

Thanks Pugilistic Animus;

I understand the IPH is educational rather than regulatory, and find this statement somewhat simplistic:...

The FAA, when left to its own devices, tends to internalize. That doesn't happen with certification regulations because they are very thoroughly vetted with industry (powerhouses like Boeing and AB).

Advisory Circulars are sometimes vetted very well but other times not.

Publications like the IPH are not vetted at all; rather they are the product of staff of varying competency and experience within the organization.

I give them an "E" for effort, but that is about it.

[Capn Bloggs]

Originally Posted by OBN

I am currently designing RNP approaches into Bandga, are you saying I should stick with the AFM climb gradients of 2.5%?.... how 'innovative'

Look at it this way, you are on final airport elevation near 5000, temp 25C, flaps 30 or 40...down to Vref around 140kts, so almost all of your energy is gone, and lose an engine. You now have to get the engine spooled up, all the bleed/icing etc off, balanced and to flaps 1 (the AFM basis for climb)...and not drop below the MDA...and is your climb near 2.5%

For a start, the AFM requires the aircraft to be able to climb at 2.1% in the Approach-climb config at the airfield elevation, so that is the immediate go-around taken care-of.

What terrain clearance parameters are you going to use for the rest of the Missed Approach?

[Zeffy]

Zeffy ...
all the pilot can do is assure that the WAT limits for approach climb are legally met

PA
And that assurance guarantees little with respect to obstacles that may be lurking in the published missed approach track.

This thread is now two years old, but is always worth another visit.

[Pugilistic Animus]

FAR 25 approach climb gradients for TERPS IAPs may be simply implied within the chart...similar to second segment limitation [a certification standard]---it might not say explicty, but implicit within other charts with an annotation such as "cross hatched area -does not meet approach climb limits" however for certain special cases it is up to the airline operation to meet FAR-121 and gain at least an equivalent level of safety as an engineering goal...altogether the TO case MUCH more difficult to meet than any other from what I've learned here from the performance engineers...

With regards to the IPH it's a very good publication aloowing pilots to better understand TERPS criteria and the NAS

Zeffy I'm in that thread...

[john_tullamarine]

And that assurance guarantees little with respect to obstacles that may be lurking in the published missed approach track.

.. again, certification Design Standards have NO interest in the rocky bits .. that problem belongs to the operator.

All the WAT limits do is give some level of confidence that the aircraft might just go up gradually ... rather than down.

[Zeffy]

Exactly. Thank you.

I should have said "guarantees nothing".

[FlightPathOBN]

Terpster,

I am currently designing RNP approaches into Bandga, are you saying I should stick with the AFM climb gradients of 2.5%?.... how 'innovative'

I would say you should stick with FAA Order 8260.52.

I was being factious. All I do is design procedures, all over the world...

What I am having trouble with is is explaining to this forum, the plain and simple fact that TERPS and PANOPS public procedure designs are ALL engine missed.

The DA/MDA and missed approach, shown on the charts, unless specifically noted, is based on all engine.

For a start, the AFM requires the aircraft to be able to climb at 2.1% in the Approach-climb config at the airfield elevation, so that is the immediate go-around taken care-of.

The DA/MDA on the plates is based on a very simple concept. You decide to go missed, and 8 seconds later, the aircraft climbs at 2.5%. This is the basis for the 'level' section. The 8 seconds takes into account the decision and aircraft reaction time. Again, you are at flaps 30 or 40, idle descent, around 140kts...and in 8 seconds, you are telling me that the engines are spooled up, flaps are at Flaps 1, and you are climbing at 2.5%? This is what the obstacle clearance surfaces are based on.