DP's, climb gradient, 2nd segment

[soarby007]

Once again I go for recurrent at Simuflite and get the usual lecture that DP's are based on single engine. I've read with interest all the posts about 2nd segment, DP's and the fact that DP's are an all engine procedure. Anyway the instructor and I got into a discussion about this and basically concluded to disagree with me, despite all the stuff I argued about that DP's are not a single engine requirement. The other guys in the class agreed with the Simuflite guy for the most part because that's what they have always heard.

Sled has done a great job with this in the past and has quoted from a draft FAA advisory circular. I did a little more research and found that Advisory Circular 120-91, Airport analysis, specifically states that DP's are a normal all engine procedure and discusses the various things to consider for airport analysis.

I'm sending this AC to the instructor and maybe he can change his performance lecture to be more realistic.

 

[HMR]

I'd be interested to hear his response. AC120-91, 7a-c is pretty clear.

 

[Looking]

DP climb gradient

While the DP are for all engine climb, unless you have a flight operations department that have looked at the specific airport and its obstacles and come up with a specific EO procedure, there are no way of knowing if you are able to clear obstacle during an engine failure.
I believe this is why most operators choose to see if they can meet the DP climb gradients since this is the only published data to compare the published airplane climb gradient data. Furthermore, it's important to make sure one compares Net to Net and Gross to Gross, since DP procedures data are Gross and airplane data often are published as Net.

 

[sleepy]

If they are for single engine, then why do they have different gradient requirements for 2 or 3 engines, but no gradient for one engine?

Don't just Part 135 and 121 operators have to figure it based on losing an engine? Then of course they have alternate procedures to follow if an engine is lost at V1 that allow them to take-off at higher weights.

 

[Amish RakeFight]

This is from the FAA Flying Handbook.

Maybe the instructor is confusing what the profile climb gradient is predicated upon.

CLIMB REQUIREMENTS

After the airplane has reached the 35-foot height with
one engine inoperative, there is a requirement that it be able to climb at a specified climb gradient. This is​

known as the takeoff flightpath requirement. The airplane’s performance must be considered based upon a one-engine inoperative climb up to 1,500 feet above the ground.

The takeoff flightpath profile with required gradients


of climb for the various segments and configurations

is shown in figure 9-38.
Note: Climb gradient can best be described as being a
certain gain of vertical height for a given distance covered
horizontally. For instance, a 2.4 percent gradient
means that 24 feet of altitude would be gained for each​

1,000 feet of distance covered horizontally across the
ground. The following brief explanation of the one-engine
inoperative climb profile may be helpful in understanding
the chart in figure 9-38.​

FIRST SEGMENT
This segment is included in the takeoff runway
required charts and is measured from the point at which
the airplane becomes airborne until it reaches the 35-
foot height at the end of the runway distance required.
Speed initially is VLO and must be V2 at the 35-foot
height.​

SECOND SEGMENT
This is the most critical segment of the profile. The second
segment is the climb from the 35-foot height to 400
feet above the ground. The climb is done at full takeoff
power on the operating engine(s), at V2 speed, and with
the flaps in the takeoff configuration. The required
climb gradient in this segment is 2.4 percent for twoengine
airplanes, 2.7 percent for three-engine airplanes,
and 3.0 percent for four-engine airplanes.​

THIRD OR ACCELERATION SEGMENT
During this segment, the airplane is considered to be
maintaining the 400 feet above the ground and accelerating
from the V2 speed to the VFS speed before the
climb profile is continued. The flaps are raised at the
beginning of the acceleration segment and power is
maintained at the takeoff setting as long as possible
(5 minutes maximum).​

FOURTH OR FINAL SEGMENT
This segment is from the 400 to 1,500-foot AGL altitude
with power set at maximum continuous. The
required climb in this segment is a gradient of 1.2 percent
for two-engine airplanes, 1.55 for three-engine airplanes,
and 1.7 percent for four-engine airplanes.​

SECOND SEGMENT CLIMB LIMITATIONS
The second segment climb requirements, from 35 to
400 feet, are the most restrictive (or hardest to meet) of
the climb segments. The pilot must determine that the
second segment climb is met for each takeoff. In order
to achieve this performance at the higher density altitude
conditions, it may be necessary to limit the takeoff
weight of the airplane.​

It must be realized that, regardless of the actual
available length of the takeoff runway, takeoff
weight must be adjusted so that the second segment
climb requirements can be met. The airplane may
well be capable of lifting off with one engine inoperative,
but it must then be able to climb and clear obstacles. Although second segment climb may not
present much of a problem at the lower altitudes, at
the higher altitude airports and higher temperatures
the second segment climb chart should be consulted
to determine the effects on maximum takeoff weights before figuring takeoff runway distance required.​

​

 

[greedypilot]

If they are for single engine, then why do they have different gradient requirements for 2 or 3 engines, but no gradient for one engine?

Haha I almost fell out of my chair reading this statement. So basically, you want to see a climb requirement for a SINGLE engine aircraft that has lost its SINGLE engine... word to the wise

IT'S NEVER GONNA BE ABLE TO CLIMB --- IT HAS NO ENGINE

maybe if they attach JATO rocket to all SE a/c lol

 

[604av8r]

Reader's Digest Condensed Version

Once again I go for recurrent at Simuflite and get the usual lecture that DP's are based on single engine. I've read with interest all the posts about 2nd segment, DP's and the fact that DP's are an all engine procedure. Anyway the instructor and I got into a discussion about this and basically concluded to disagree with me, despite all the stuff I argued about that DP's are not a single engine requirement. The other guys in the class agreed with the Simuflite guy for the most part because that's what they have always heard.

Sled has done a great job with this in the past and has quoted from a draft FAA advisory circular. I did a little more research and found that Advisory Circular 120-91, Airport analysis, specifically states that DP's are a normal all engine procedure and discusses the various things to consider for airport analysis.

I'm sending this AC to the instructor and maybe he can change his performance lecture to be more realistic.

My 2 cents...

The numbers in DPs are what it takes to clear the obstacles. The DP's minimum gradients don't care if you use 1, 2, or 5 engines.

Where this whole single engine stuff comes into play is in the aircraft's performance section. Those numbers are based on your aircraft's single engine climb performance, which is what the Feds expect you to use when flying a DP.

Hope this helps!

 

[wtrav8r]

My 2 cents...

The numbers in DPs are what it takes to clear the obstacles. The DP's minimum gradients don't care if you use 1, 2, or 5 engines.

Where this whole single engine stuff comes into play is in the aircraft's performance section. Those numbers are based on your aircraft's single engine climb performance, which is what the Feds expect you to use when flying a DP.

Hope this helps!

I agree with 604.

The feds want to see if you could make the DP on one engine.

I want to see if I could make it on one also, not satisfy the fed's requirement, but my own requirement of not hitting any obstacles.

Recently, we subcribed to Aircraft Performance Group's (APG), Emergency Escape Procedures. With that being said, I know what weight I could TO with, lose an engine, and continue without hitting any rocks (however, the procedure may be different than the DP).

Each airport analysis is 20 bucks, well worth the money.

 

[EatSleepFly]

Haha I almost fell out of my chair reading this statement. So basically, you want to see a climb requirement for a SINGLE engine aircraft that has lost its SINGLE engine... word to the wise

IT'S NEVER GONNA BE ABLE TO CLIMB --- IT HAS NO ENGINE

maybe if they attach JATO rocket to all SE a/c lol

"Single engine" as in one engine out on a two engine airplane.

 

[sleepy]

"Haha I almost fell out of my chair reading this statement. So basically, you want to see a climb requirement for a SINGLE engine aircraft that has lost its SINGLE engine... word to the wise"

I guess I should have been more clear. DPs are considered normal, all engine procedures and do not require the application of one engine inop net climb path computations to be legally accepted and flown. All PD's based on TERPS or ICAO Pans-Ops are based on normal (all engine) operations. They do not necessarily assure engine-out obsticle clearance.

For second segment climb the gross climb gradient for a 2 engine aircraft is 2.4% and for a 3 engine aircraft it is 2.7%. That must be reduced by .8% for 2 engine aircraft and .9% for three engine aircraft and 1% for 4 engine aircraft to obtain net climb gradient. That gets you to 1500' AGL. You have to clear all obsticles by 35' vertically or by at least 200' horizontally within the airport boundry and by 300' horizontally after passing the boundry.

The minimum climb for a DP is 200'/NM. That gives you clearance of .8% above OIS for the DP. You can do this using gross climb gradient.

If you lose an engine on a DP your only requirement is to use an alternate procedure in lieu of climb gradient to clear all obsticles. If it's VMC you can do it visually. You can also buy an alternate procedure from Jepp Opsdata or APG. But, you do not have to assume that you will be flying the DP with an engine inop (which I should have said instead of single-engine since obviously a single engine aircraft doesnt have a climb gradient when the engine quits).

 

[Beechjetr]

Has anyone ever seen a 2 engine climb chart for a Beechjet?

 

[tk855]

Has anyone ever seen a 2 engine climb chart for a Beechjet?

I wouldn't worry about it, more than likely it won't be able to do it!

 

[FlyFlyFly]

The way I see it, I owe it to my family, passengers and the company to be able to make the climb gradient single engine.

The rest of it is academic...

 

[Lead Sled]

Has anyone ever seen a 2 engine climb chart for a Beechjet?

Has anyone ever seen an "all-engines operational" climb chart for any of the multi-engine turbo-jet aircraft we're flying? I you have, let me know - the manufacturers are required to give you that data and they don't. So how do we know that we can even do it under normal conditions? Soarby007 it's going to take time for this "new" concept to drift down to the various instructors. I've sat in on some performance classes where the instructors were pretty incredulous. Early on, I found it best just to sit back and smile. Fortunately, it's changing and I agree with HMR, the AC is pretty clear and you did what I would have done - forwarded the reference so that he can look it up and read it for himself.

LS

 

[soarby007]

My 2 cents...

The numbers in DPs are what it takes to clear the obstacles. The DP's minimum gradients don't care if you use 1, 2, or 5 engines.

Where this whole single engine stuff comes into play is in the aircraft's performance section. Those numbers are based on your aircraft's single engine climb performance, which is what the Feds expect you to use when flying a DP.

Hope this helps!

Actually I disagree with this. The "Feds" just published the AC 120-91 emphasizing that DP's are not single engine procedures and never designed to be.
Not all DP's are obstacle procedures. However, on some DP's I may not want to continue to climb on one engine just to complete the procedure. LAS is a good example on the Cowby2. Why would I continue toward the mountains on one engine. That's why you need an escape procedure in an emergency. I wouldn't want to complete a normal DP procedure, in all cases(in an emergency), simply to say that I complied with the regulations.

The performance numbers in most business aircraft are good to 1500', that's it. In the Westwind, there is not one shred of data to indicate what airspeed, climb rate, etc is to be accomplished after 1500', on one engine to meet any gradient. There happens to be a two engine rate of climb chart, but not a single engine climb chart. Also, this AC 120-91 points out that a number of things will degrade your climb gradient, i.e. angle of bank, temperature, etc., all the things we all know. None of this is in the manufacturer's data.

I agree that APG has good information for an escape procedure, not necessarily designed to a DP, but to get you somewhere safely.

Like I told the instructor, you still have to have a plan after 1500'. What will it be? And how will you accomplish it thru proven data not guesswork, such as a V2 plus something. You can't take off knowing that the DP's are all engine procedures, clutching your lucky rabbit foot in hopes nothing will happen. My TFE731 failed at 20,000' last year, could have been at 400' or 8,000'.

Gotta have a plan.

 

[LJ45]

Ok, I just read that AC. Now I am dumber than before, I'll have to take the butchers word on this one.

 

[GatorAir]

The AC does not negate the requirement to avoid obstacles with an engine inoperative and to read it that way falls short. The AC simply describes the basics for the design of departures for third parties. It does however describe the underlying requirements.

From AC 120-91

10. METHODS OF ANALYSIS. Sections 121.189, 135.379, and 135.398 require that the net takeoff flightpath clears all obstacles by either 35 feet vertically or 200 feet laterally inside the airport boundary, or 300 feet laterally outside the airport boundary.

The one engine inoperative requirement is harder to find but is present in the CFRs quoted in the AC. The first one for example, 121.189 states (among other things):

2) In the case of an airplane certificated after September 30, 1958 (SR 422A, 422B), that allows a net takeoff flight path that clears all obstacles either by a height of at least 35 feet vertically, or by at least 200 feet horizontally within the airport boundaries and by at least 300 feet horizontally after passing the boundaries.

and it goes on to say:

g) For the purposes of this section the terms, takeoff distance, takeoff run, net takeoff flight path and takeoff path have the same meanings as set forth in the rules under which the airplane was certificated.

Part 25 contains those rules and defines Takeoff Path as (again among other things):

(2) The airplane must be accelerated on the ground to VEF, at which point the critical engine must be made inoperative and remain inoperative for the rest of the takeoff;

The other CFRs quoted have similar language.

Just beacuse the AC states SIDs assume all engines operating doesn't alleviate the basics. If there is a reverse print "T" on the plate then there is an Obstacle Departure Procedure (ODP) for that airport and you should look it up in the front and comply with it one engine inoperative for commercial operations. If there's none then a minimum of 200 FT/Nm is required, 3.3%, again one engine inoperative. The AC itself states in the begining:

This AC need not serve as the sole basis for determining whether an obstacle analysis program meets the intent of the regulations.

Why we use one engine inoperatve versus say the gear remaining down? Arbitrary. Ironically I've had the gear stay down on me three times but have never lost an engine below 1000'. But that's the way it is.

 

[Junkflyer]

Maybe I'm missing something , but we have pink pages in our Jepps which are engine failure departures for specific runways at certain airports. SFO, ANC, and HNL are examples.

 

[G100driver]

Maybe I'm missing something , but we have pink pages in our Jepps which are engine failure departures for specific runways at certain airports. SFO, ANC, and HNL are examples.

3/4 of the guys out here in the corporate world have no idea what you are talking about. Alternate Departure Procdures are just starting to take hold, but FSI is still way behind the power curve in teaching these.

 

[Beechjetr]

I guess I'm in the 3/4. What are the pink Jepp pages about? They sound real good.