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-   -   GA Operators Performance Calculation Methods? (https://www.pprune.org/biz-jets-ag-flying-ga-etc/266655-ga-operators-performance-calculation-methods.html)

Kerosene 4th Mar 2007 20:50

GA Operators Performance Calculation Methods?
Hello All,
I'm starting this thread in order to bring up a discussion about an important safety issue.
After flying for Airlines for more than 10 years, I made a change into GA to fly a long range bizjet for an operator and (JAR OPS) AOC holder in a JAA member state.
One of the most noticeable differences to all airlines I had worked with in the past is the lack of Take Off and Landing Runway Analyses Tables, Charts or Software programs to determine the max T/O or landing weights for the respective airports/runways operated under various ambient conditions, including Engine Out Contingency Routes.
I am surprised to see that the operator does not give this any consideration. With the usually short notifications before flights, it is virtually impossible for a flight crew to make correct and safe performance calculations with no other reference than the AFM, especially with respect to obstacle clearance.
According to JAR OPS 1, Subpart G, the operator of performance class 'A' airplanes is responsible for establishing procedures to determine maximum operating masses for all conditions, and to ensure that obstacle clearance criteria are met in case of engine failure.
This requirement is clearly not complied with by that operator, and as I learned also by other commercial GA operators in that same JAA member state.

If you could share if and how Performance is calculated in your GA operation it would be greatly appreciated!

Doodlebug 5th Mar 2007 09:23

Hello Kerosene

I fly a Global which has the ABACUS performance-software installed on the aircraft laptop. Doing the mass and balance as well as the performance calculations is a doddle, even on short notice, as you say. The given sectors' pilot flying will run the numbers as a part of the cockpit-setup, and print them out on board, in duplicate. One set of papers stays behind with the handling-agent. As a backup I've installed the same software on my personal laptop. This means that I can come up with 'can we go or not' answers without being on the airplane.

I doubt you'll find many operators spending the required money on runway analysis in the bizzjet world, seeing as everything is unscheduled. All the more reason to read every last nuance on the jepp-plates and to do the calculations.



BizJetJock 5th Mar 2007 09:26

Hi there,
As a freelance guy I fly for quite a few different operators (private and commercial) under different regulatory regimes, and they fall into 3 categories.
About 5% have full runway analyses done either by third parties or with a laptop tool with a worldwide database.
80% work on the principle that if you can make the SID gradient even with an engine out (3.3%/200ft/nm unless more stated on plate) then you are OK. There are some times when this can be restrictive, but it seems to work.
Around 15% ignore the problem and hope it will go away....:ugh: :mad:
Needless to say, I always work on the second if the first is not available - even if the rest of the crew aren't. And I try to educate them, but sadly if they are not aware of the problem it often seems to be because they really don't understand and IMHO shouldn't be flying around outside an airline ops structure.

CL300 5th Mar 2007 09:44

Netjets Europe is using Flygprestanda runway analysis and contingency routes, for ALL airports, ALL airplanes, EVERY flights. No having them is a no go. So bad that you can not accept an interception take off if the chart is not at hand (ie in the cockpit). Brace from the S interception in FRA or Y in GVA. or A4 in CPH...among other.
Fly safe and stay out of the trees !

Kerosene 5th Mar 2007 12:28

Very good to hear that Netjets is using a professional company to support them. Of course, we all know not being allowed to accept intersection S in FRA without the appropriate chart might seem a bit 'over the top', but trust me, better like this than the other way around, i.e. operating to Innsbruck without any training or calculations.

unablereqnavperf 5th Mar 2007 12:33

Anybody put there have a computor programme for calculating Lear 45 perf?

Kerosene 5th Mar 2007 12:54

Thanks Bug,
As far as I know Abacus gives you a balanced field calculation for DRY and WET runways only, and a climb gradient, but no engine out escape routes.
The W&B has a nice graphical interface, tailored to the seating configuration of the individual tailnumber.
On an aircraft as the Global, you might be able to match or exceed the SID gradient in most cases, but for an aircraft not as powerful this can quickly become very limiting (such as many Citations, Legacies,...).
The lateral requirements for a SID are far greater than for an engine out flight path, therefore the SID has to account for obstacles that are much further away, resulting in high gradient requirements.
However, I'd already be happy to have this, better than nothing.
Happy Landings,

CJ Driver 5th Mar 2007 20:20

SID Gradient
We certainly fall into the majority camp described by BizJetJock - if you can make the SID gradient OEI, you are good to go. And despite Kerosene's comments, even the humble Citation is not often limited by that strategy.

And if you can't make the gradient? Buy less fuel and plan on a tech stop!

galaxy flyer 5th Mar 2007 23:32

The group I'm with (corporate) has begun using APG out of Colorado for runway analysis. Very nice, online or on Blackberry!, flexible and does OEI routes in a format that can be loaded as a secondary flight plan for instant use. Very good and highly recommended.


Niterunner 19th Nov 2013 19:33

Second segment
Hello all,
I would like to resurrect this thread, or if it has been discussed somewhere else, please paste the link as I could not find it.
It seems that performance is too often ignored in non airline environment, but all airplanes fly the same so we should have the same safety standards as the airlines and charter operators.
While looking for WB/performance software I found that APG escape routes just added work load and more possibility for error to an already challenging situation. It was mostly for this reason that I chose EFP-Pro for our operation.
I'll be honest here and admit to this being a weak area and I blame it on lax regulations and therefor weak training standards. I have also worked 135 and we used to run the numbers for each flight, but I'm not so sure we were doing it right beyond 1st segment. I wish to remedy this oversight and learn as much as possible about performance and obstacle clearance.

I have recently heard a few things that made me decide to write about this.
-Runway Analasys, (APG), escape routes often parallel or copy the DP, so they are really no big deal to fly much of the time.
-EFB-Pro uses net flight path, (adjusted for temp), unlike some others.
An argument was made for APG type software that reminded us that "current" airport conditions must also include NOTAMS for obstacles to be considered into the runway analysis as the the DP does not have to clear obstacles.

There seems to be a lot of confusion and lack of understanding in this area.
While in recurrent this year we were presented some videos about second segment planning and how calculations are made.
TAPP TAPP Working Group Video (Part 1 of 4): Planning For Takeoff Obstacle Clearance - YouTube

If anyone has any reference material they wish to share that could help the rest of us, (or maybe just me), better understand and apply to our daily routine, please post here.

I have been flying left seat many years and am always looking to learn as much as possible to improve safety, but we must be proactive as the "old way" is not always the best way.

mutt 20th Nov 2013 00:34

As you are familiar with EFB-PRO, go to their site and download their little book about takeoff analysis and obstacles, its extremely interesting.

silverknapper 20th Nov 2013 01:57

Another vote for APG. IPhone app.

south coast 20th Nov 2013 09:39


The only problem I have with the way that you say 80% of the GA industry do it is are they actually doing that correctly or just using second segment performance figures and saying that figure exceeds the SID gradient requirement?

From my own personal experience, if one wants to actually calculate via the AFM the climb gradient to an altitude that a SID may state (which is normally higher than the end of the 2nd segment which I think is what people are using as a figure that if it exceeds the SID gradient then some accept they are safe) and factor in turns, then it is not a quick or easy job, so I am a little sceptical when people say the OEI climb performance is better than that required by the SID.

BizJetJock 20th Nov 2013 10:40

South Coast - I agree entirely; many of the people who espouse this method still don't do it properly, not least because that would give pretty hefty performance penalties at many airports which is terribly inconvenient...:ugh:
Certainly on the AOC side, though, in the 6 years since I wrote that proper analysis using FlygP or APG has become much more widespread.

Minor point of order, Bizjetjockey is some young upstart who chose his name a good five years after I started posting here. :)

ginopino 20th Nov 2013 11:45

We are using APG for RWY Tables and Contingency Procedures.... for less than 100 dollars/month you can print unlimited RWY Analysis Tables per Tail N.

Have a look... APG - Aircraft Performance Group

Cheers !

ginopino 20th Nov 2013 11:49

Video Library - APG

south coast 20th Nov 2013 12:05

BizJetJock, my apologies for the additions to your name?

F900Ex, indeed you are correct, however my point was mostly referring to two engines planes.

Even with the three engines, using the 2nd segment climb figure to see whether you can make a SID performance limitation to an altitude above 1500' is not correct, agree or disagree?

CL300 20th Nov 2013 12:31

South Coast , you are indeed correct. But the issue is not necessarily the SID limitations, one's will find that the most restrictive obstacle are very often close-in obstacles and not the second segment as per say.
As a consequence a proper runway analysis is always preferable.
If someone like to have a good video i can recommend this one

even if it is applying to OPS-Specs and Terps, it remains totally valid for PANS-OPS and EASA ( with different numbers); in terms of assessments

south coast 20th Nov 2013 12:51

F900 Ex and possibly CL300, I think we work for the same company and I am very happy that we use Flyp for perf as I wouldn't ever get into the air if I had to use the AFM!!!

My point was merely that I am not confident that the 80% that BizJetJock refers to are doing it correctly.

BizJetJock 20th Nov 2013 14:22

And I'm confident they're not! :eek:

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