Types of Climbs

[blueskies8]

That's true for some manufacturers but several provide net climb gradient in lieu of gross gradient.

You are correct and I stand corrected.

 

[vballindaytona]

1.6% is a SE net climb gradient (2.4% gross) required during the 2nd segment of part 25 certified aircraft. 3.3% gross (2.5% net) is the standard second segment climb gradient required by TERPS but it is not SE even though we must meet it SE. If we can't meet the TERPS 2nd segment climb gradient SE then we must have an alternate obstacle DP or visual see and avoid procedure. All the 2nd segment charts in the AFM give you gross climb numbers. Hope that helps.

so do we have to meet 2.4 or 1.6 for second segment? what do we have to meet net or gross? and what is the defination difference between net and gross for these examples. thanks! does it just matter what your specific charts are in your afm? in other words if my charts say gross then i have to make 2.4 and if they are net i have to meet 1.6 for second segment?

 

[T-1GUY]

The key is to look at the title of the chart or the climb gradient key. It will specify if the chart is a "gross" climb or "net climb". Remember, that we need to meet a net climb. If using a gross climb chart, subtract .8% from the gross answer to get the net climb answer. Then compare this answer to the climb gradient required by the departure. The technique of usining the 100 kt ground speed table is the quickest way of figuring out the gradient needed for the departure.

 

[guido411]

As simply as I can explain a difficlt topic. . .

so do we have to meet 2.4 or 1.6 for second segment? what do we have to meet net or gross? and what is the defination difference between net and gross for these examples. thanks! does it just matter what your specific charts are in your afm? in other words if my charts say gross then i have to make 2.4 and if they are net i have to meet 1.6 for second segment?

YOU must meet minimum 1.6% climb (net) in a Part 25 airplane ALWAYS.

A TEST PILOT had to show 2.4% (gross) during certification in a Part 25 airplane.
The 0.8% difference from gross to net is to adjust for factors such as: test pilot is better than you, test pilot has perfect airplane, test pilot KNOWS the failure is coming, etc.

Think of the term "net" applying to you and me and the term "gross" applying to test pilots during certification. You won't use the term "gross" in day to day operations. We only discuss the term "gross" in training to help us all clumsily grasp the topic.

TERPS is a whole other barrel of monkeys. It's for obstacle clearance. The 1.6% does not garuntee any obstacle clearance. The 3.3% number you've seen tossed around has to do with IFR. To takeoff into IFR conditions (less than 1000-3) you must be able to meet a 3.3% gradient ALWAYS in a Part 25 airplane.

You must be able to maintain GREATER than 3.3% if the TERPS survey deems it neccessary. An easy way to find what the actual gradient required is (as somebody previously mentioned) to look at the 100kt box and look at the required fpm climb. If it says 550 fpm climb required that means it's a 5.5% "gradient".

As for your question about which chart in the AFM. . .my Part 25 airplane experience is limited but I feel I have a good grasp on the topics being discussed. I can only tell you that in my airplane the is a "Net Climb Gradient" chart. There is also a chart that shows maximum weight under the day's conditions to meet the 1.6% for certification.

Clear as mud, right?

 

[vballindaytona]

YOU must meet minimum 1.6% climb (net) in a Part 25 airplane ALWAYS.

A TEST PILOT had to show 2.4% (gross) during certification in a Part 25 airplane.
The 0.8% difference from gross to net is to adjust for factors such as: test pilot is better than you, test pilot has perfect airplane, test pilot KNOWS the failure is coming, etc.

Think of the term "net" applying to you and me and the term "gross" applying to test pilots during certification. You won't use the term "gross" in day to day operations. We only discuss the term "gross" in training to help us all clumsily grasp the topic.

TERPS is a whole other barrel of monkeys. It's for obstacle clearance. The 1.6% does not garuntee any obstacle clearance. The 3.3% number you've seen tossed around has to do with IFR. To takeoff into IFR conditions (less than 1000-3) you must be able to meet a 3.3% gradient ALWAYS in a Part 25 airplane.

You must be able to maintain GREATER than 3.3% if the TERPS survey deems it neccessary. An easy way to find what the actual gradient required is (as somebody previously mentioned) to look at the 100kt box and look at the required fpm climb. If it says 550 fpm climb required that means it's a 5.5% "gradient".

As for your question about which chart in the AFM. . .my Part 25 airplane experience is limited but I feel I have a good grasp on the topics being discussed. I can only tell you that in my airplane the is a "Net Climb Gradient" chart. There is also a chart that shows maximum weight under the day's conditions to meet the 1.6% for certification.

Clear as mud, right?

ha, thanks guido, good info

 

[guido411]

One more thing for the original poster. . .

You DO understand that all this gradient talk refers to one-engine-inoperative (OEI) operations, right? We all have to assume we're going to lose an engine on every takeoff and be able to ensure that we won't kill ourselves.

Sorry if that insults your intelligence but if a guy hasn't flown a transport category airplane before he might not know that. Good luck.

 

[blueskies8]

Yes at a minimum you have to meet 1.6/2.4 in your 2nd segment but you will more than likely be restricted with a higher climb gradient from a DP. A standard DP with no specified climb gradient requires a 3.3% gross (2.5% net) climb gradient. Like it has been mentioned here before if the DP climb gradient is greater than 3.3% the 100kt column in the ground speed vs. fpm table is quickest way of determining what it is. For example, if the 100 kt column calls for 440ft/nm then the climb gradient required for that DP is 4.4% gross. Once you know the climb gradient required you can go to the AFM and find your aircrafts capability. If you need to meet 4.4% gross climb gradient from the DP chart and you are using data from a "net" climb gradient chart in the AFM you would require a 3.6% net climb gradient to comply with the DP and using a gross climb AFM chart would obviously be a 4.4% requirement. The AFM's that I have dealt with have separate charts to show weight vs. temp that will allow you to make the certification numbers of 1.6% net (2.4% gross) and those charts are called the "Maximum Takeoff Weight Permitted by Climb Requirement". They do not show what your climb gradient will be as it is assumed 1.6/2.4 but they show the weight and temp that will allow you to comply with the certification numbers. I have only run into a certification climb gradient weight restriction once and that was at BJC at 32 degrees Celsius. The way that we were pointed in that direction was that for our desired takeoff weight and pressure alt the the temp stopped at 25 C on the takeoff distance chart. The next place we looked was the certification chart and determined that could not take as much fuel as we wanted to. Luckily we hadn't fueled yet. Sorry for the long story. In short I am glad I have this understanding of the system but really like the Collins smart perf and our new EFB's.

 

[blueskies8]

You DO understand that all this gradient talk refers to one-engine-inoperative (OEI) operations, right? We all have to assume we're going to lose an engine on every takeoff and be able to ensure that we won't kill ourselves.

Guido and I must have been posting at the same time but yeah, what him said.

 

[OPECJet]

Thanks for the replies.

 

[GooseHZ]

Or.....

Froget all that stuff and just


Push


Pull


Pray..... lol


good luck!!!