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).