Pt. 91 Climb gradient

[semperfido]

Just call Jeppesen and ask for Ops Data. There is a short questionair to fill out and a few days later you get your alternate procedure.

'Sled

what is jepps alternate proc for ASE?

 

[Ty Webb]

You guys are professional pilots, right? You're supposed to know this stuff.

It's not under 91, it's under Part 25, and if you are flying an aircraft certified under this part (ie Transport Category Turbojet > 12,500 MTOW) then you certainly do have to comply with required climb gradients under 91, 135 or 121.

As for an Obstacle DP, you either have to comply with the published procedure, or have determined an alternate means of compliance.

Sheesh.

 

[Lead Sled]

OK I have a flak jacket on now. If the WX is IFR then you must be able to comply with the gradient of the SID 91 or 135. Correct? Please correct me if I am wrong. If I am wrong so be it, I aint a changing!

Flak jacket not required. Yes, you must be able to comply with the gradient of the DP regardless if you are operating under Part 91, 135 or 121. Period. Where most guys get wrapped around the axle is that they interpret that to mean that they must be able to do it after they have lost an engine. That is not correct. There have been many good threads and posts on this very topic and it has been beat to death.

Odd as it seems, Part 91 there is no specific reg to prevent you from launching IFR when you can't make the gradient single engine. That being said, I know of a Challenger crew that got clobbered after flying to the east coast from a certain airport in CO. When they landed, a fed met them and asked 'what did you weigh at takeoff'? Both crew got popped with 91.13 (the careless and reckless thing).

I had also heard of that aviation urban myth. The story, as it is told, is a myth. There is nothing illegal, immoral or fattening with operating above your "single-engine DP climb gradient" weight. Aspen 121 operators do it routinely. They have alternate procedures that allow them to safely do this. Again, this has been discussed on this forum before.

Common sense and the desire for self-preservation will tell you that you have to be able to keep your nose out of the dirt in case you lose an engine. Many good aircraft simply don't have the performance to fly out of airports like Aspen with anything approaching a useful payload and make the climb gradients specified in the Lindz4 after the loss of an engine. This is where the alternate procedures provided by Jeppessen OpsData and others come in. It gives you a legal alternative to the published departure procedure IN THE CASE OF AN ENGINE FAILURE OR OTHER EMERGENCY THAT WOULD KEEP YOU FROM BEING ABLE TO MAKE THE CLIMB GRADIENT SPECIFIED IN THE DP. Remember, climb gradients specified in DPs are based upon the operation of ALL engines.

I've got a question for you guys that are using your takeoff performance data to generate single-engine performance numbers for an airport (ASE) at nearly 8,000' msl and a DP climb gradient requirement to 14,000' msl. How are you coming up with valid numbers? (Please take a second look at the definitions, notes, stated configurations, stated conditions, etc. on your specific charts before you answer.)

'Sled

 

[HMR]

what is jepps alternate proc for ASE?

It's a DME arc off of DBL that brings you down the valley and ends in a hold just west of LINDZ. I plotted the waypoints on a VFR chart and connected them with a line. Took about 15 minutes with MicroSoft Paint. We keep it handy on ASE departures. It's easier/safer to use than the ops data alone.

 

[HMR]

I've got a question for you guys that are using your takeoff performance data to generate single-engine performance numbers for an airport (ASE) at nearly 8,000' msl and a DP climb gradient requirement to 14,000' msl. How are you coming up with valid numbers? (Please take a second look at the definitions, notes, stated configurations, stated conditions, etc. on your specific charts before you answer.)

I knew that was coming. Can't wait to read the answers.

Good job 'Sled.

 

[G100driver]

Ain't touching that one!!!

This is entire reason for turn procedures and alternate DP's!

 

[rice]

I've got a question for you guys that are using your takeoff performance data to generate single-engine performance numbers for an airport (ASE) at nearly 8,000' msl and a DP climb gradient requirement to 14,000' msl. How are you coming up with valid numbers? (Please take a second look at the definitions, notes, stated configurations, stated conditions, etc. on your specific charts before you answer.)

'Sled

Don't have the manuals handy right now but I'm "guessing" that it probably has something to do with a 1500' reference.
Should make for some interesting answers from the group.

'Sled, do you guys ever shoot the GPS Z or Loc/DME 15 ??

 

[johnny taliban]

I'll take a stab at that question. I believe that the correct answer is to go to your performance charts and determine your performance from 14,000 feet instead of 8,000 feet. The numbers you get off the tables only guaruntee single engine performance to 400 feet agl, therefore using the numbers from your 8,000 feet page will NOT provide you the obstacle clearance (14,000) that you need coming out of Aspen.

then again,I could be wrong
Johnny

 

[Lead Sled]

I'll take a stab at that question. I believe that the correct answer is to go to your performance charts and determine your performance from 14,000 feet instead of 8,000 feet. The numbers you get off the tables only guaruntee single engine performance to 400 feet agl, therefore using the numbers from your 8,000 feet page will NOT provide you the obstacle clearance (14,000) that you need coming out of Aspen.

Johnny, the answer that you gave is typical of the normal responses that most pilots would give. However, there are several reasons you cannot use AFM 2nd segment climb data in meeting TERP's (departure procedure) 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 and CANNOT be used to the heights demanded of certain DP's such as is the case of Aspen’s LINDZ4 departure - 7,820 ft to 14,000 ft. As you said, 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.

Additionally, 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. (6000’ worth of change in the case of Aspen.)

Remember if you try to use 2nd segment climb charts, you'll only achieve 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. It can not be extrapolated beyond that.

'Sled

 

[some_dude]

Under 91, you do need to comply with the gradient with all engines operating (duh!). There is no specific requirement to comply with the gradient with an engine inoperative.

If an engine fails and you crash into the obstacle then you will be violated for being "careless and reckless."

Keep in mind that I am talking strictly about regulations, not necessarily about what is safe or smart.

Lead and I have already beat the 135 issue to death in another thread. I'm staying away from that one.

OK I have a flak jacket on now. If the WX is IFR then you must be able to comply with the gradient of the SID 91 or 135. Correct? Please correct me if I am wrong. If I am wrong so be it, I aint a changing!

 

[gunfyter]

Additionally, there's the consideration of 5 minute limitation on takeoff thrust.

Remember if you try to use 2nd segment climb charts, you'll only achieve 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. It can not be extrapolated beyond that.

'Sled

Screw the 5 minute limitation. I am not pulling the throttle back.

I do not think there is a limitation on keeping t/o flaps in or V2. Both should be maintained until obstacles are cleared. Normally retract flaps at 400' maybe should consider keeping T/O flaps until clear of obstacles at ASE. So no matter where eng fail occurs one is configured for second segment climb.

Now if the T/O flaps are still in with TO power set, why would the climb gradient not be valid anymore beyond 400'?

 

[Lead Sled]

Gunfyter...
The certification climb gradients are based on wings level flight. Depending on engine out data for meeting TERPS criteria may leave you in hole if you're not careful. A representitive of the FAA's Aircraft Certification Office in Renton WA said, in a conference, that (concerning the use of Part 25 engine-out performance data to comply with TERPS) these two performance requirements are independent and any simple cross use could result in non-compliance with the desired criteria. TERPS doesn't necessarily account for close-in obstacles near the departure end of the runway, and engine-out flight path data doesn't necessarily result in the steady gradient or "plane" that TERPS is based on. This is clearly seen by the differences in flight path gradients between the first and segment segments on most transport aircraft. There are other limits to consider too, such as the maximum altitude to which the climb gradient was calculated, and the maximum time limit on the use of takeoff thrust, which can not be exceeded. When he was asked about possible future inclusion of all engine performance data for transport category aircraft, he said that has been discussed at various times in the past, but has been rejected each time.

Engine failure obstacle clearance procedures are the sole responsibility of the operator under 121.189(d) or 135.379(d). As has been pointed out, no requirements for engine-out obstacle clearance are imposed on 91 operators under 91.605. The question of engine failure during the SID and safe escape routing is the subject of Performance Harmonization Working Group as outlined in draft AC 120-OBST. A copy of the draft is as follows:

Subject: AIRPORT OBSTACLE ANALYSIS
Date: DRAFT
Initiated By: AFS-400
AC No: 120- OBS-11

8. TERPS CRITERIA VS. ENGINE-OUT REQUIREMENTS:
a. Standard Instrument Departures (SIDS) or departure procedures (DPs) based on U.S. Standards for Terminal Instrument Procedures (TERPS) or ICAO Pans-Ops are based on normal (all-engine) operations. Thus, engine-out obstacle clearance requirements and the all-engine TERPS requirements are independent. Engine-out procedures do not need to meet TERPS requirements. Further, compliance with TERPS climb gradient requirements do not necessarily assure that engine-out obstacle clearance requirements are met. Terminal instrument procedures typically use specified all-engine climb gradients to an altitude, rather than certified engine-out airplane performance. Terminal instrument procedures 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 FAR requirements for the development of takeoff performance data and procedures. There are differences between TERPS and engine-out 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, SID's, DPs, and other normal operating considerations.

American Airlines published a technical bulletin for their pilots regarding the question of engine-out obstacle clearance on a SID. It directly pertains to this discussion:

Flight Operations Technical Informational Bulletin
May 1997 Number 97-03

Obstacle Clearance on SIDs

Distribution List 600 - All Cockpit Crewmembers
This bulletin for information only. Retain or destroy at your option.

Aircraft climb capability on Standard Instrument Departures is more than adequate during normal, all-engine, operations. SIDs are designed so that a climb gradient of no more than 200 feet per nautical mile will provide obstacle clearance, or, if a steeper climb is required, it will be specified on the SID chart. However, if an engine failure occurs while flying the SID two questions arise.

1. Has the flight path specified in the SID been analyzed for engine-out capability?
2. Have the TPS weight limits been adjusted to account for the terrain or obstructions on the SID if an engine fails?

Obstacle Clearance Criteria

FARs require that operators adjust maximum allowable takeoff weights to ensure obstacle clearance following an engine failure at V1. The aircraft must clear all obstacles (man-made or terrain) in the flight path by horizontal and vertical margins specified in the FARs. The vertical margin is 35 feet at the end of the runway, increasing incrementally with distance from the runway.

The horizontal margin, which accounts for factors such as crosswind and piloting variables, begins with a width of 300 feet on either side of the flight path, increasing to 2000 feet for straight-out flight path, or 3000 feet for turning flight path. If the engine-out runway analysis determines that a limiting obstacle exists in the straight-out path the takeoff weight must be restricted, or a special turning procedure must be provided to avoid the obstacle. This procedure will normally be published on an Ops Advisory page for the airport.

TPS Obstacle Clearance Analysis

The TPS is programmed to adjust runway limited takeoff weights as necessary so that the engine-out performance will meet the obstacle clearance requirement. The flight path for engine failure analysis is assumed to be along the extended runway centerline or the
flight path specified on a special engine failure procedure.

In the event of an engine failure after the completion of the third segment climb (flap / slat retraction), the departure procedure (SID, radar vector, or climb on course) is not analyzed for engine-out obstacle clearance because of the infinite number of variables.

Flying After the Engine Failure

If an engine failure occurs at V1, obstacle clearance has been analyzed for a straight-out path or a special engine-out departure path. If any other flight path is flown prior to the completion of the third segment climb (flap / slat retraction), obstacle avoidance is the responsibility of the flight crew. Furthermore, after the completion of the third segment climb (flap / slat retraction) or the published engine-failure departure procedure, the flight crew becomes responsible for terrain avoidance. It is unlikely, but possible, that rising terrain in the takeoff path could result in an obstacle being below the required margin, but penetrating the GPWS envelope resulting in a "TERRAIN TERRAIN" or "TOOLOW GEAR" warning. Unless visibility is sufficient to assure obstacle clearance, it must be assumed that the GPWS warning
is valid so escape procedures must be accomplished to the extent possible given the configuration and available climb capability.

An engine failure after the airplane is established on a SID may require a climb gradient of 200 feet per mile (or higher if specified by the procedure) to assure obstacle clearance (this is about 800 fpm climb at 240 knots ground speed). At average takeoff weights our airplanes can generally maintain this climb gradient with an engine failure, however at heavy weights, especially with anti-ice on, the climb capability may be as little as 70-90 feet per nautical mile. If the necessary climb gradient cannot be maintained, the flight crew must be aware of obstacles and take whatever emergency action may be necessary to avoid them.

Summary

Runway analysis is a tool with inherent limitations. It is intended to ensure engine-out obstacle clearance from lift off through the third segment climb (flap / slat retraction).

After the "top of climb" waypoint, the Mountainous Terrain program will begin to analyze the route of flight and provide driftdown enroute engine-out alternates if the engine-out performance does not permit continuation of flight.

In the event of an engine failure between the completion of third segment climb (flap / slat retraction) and the "top of climb", the flight crew must maintain situational awareness and avoid terrain.

We have asked Jeppesen to provide terrain features on STARs and SIDs especially in areas of high, or rising, terrain. In the meantime, obstacle and terrain information can be found on approach charts, 10-1 area charts and other sources. The Air Traffic Controller, GPWS and Enhanced GPWS may offer additional information and warnings.

Guys, do your homework and, if it applies to your operation, get Jeppesen OpsData involved. You’re making this whole thing way too difficult.

 

[HMR]

Good work 'Sled.

Hey Moderators- How about posting this in a "FAR FAQ" section so 'Sled doesn't have to keep typing this up every few weeks?

 

[English]

HMR, I agree. Maybe a "sticky" in the FAR forum.

Unfortunately it's unlikely a moderator will read this (except maybe Falcon Capt). Seems ya have to send a PM for things of this nature.

 

[HMR]

Unfortunately it's unlikely a moderator will read this (except maybe Falcon Capt). Seems ya have to send a PM for things of this nature.

Ah yes, a PM. Much better than my idea. I was just going to post something about Pacific Jet. That always seems to get a quick moderator response.