TO calculations

[Kristian17]

I do not understand how you can calculate the field/obstacle limit weight? In my 767 QRH there is no way of finding this out. How do you calculate how long the TO run will be? The minimum overall thrust to get off the rwy (TO analysis to work out the required thrust)?

Thanks for your help!

Kristian

[john_tullamarine]

You are confusing the certification rules and how the OEM chooses to present the data to permit compliance with those rules. AFM/QRH presentation can vary from the old traditional British way of giving you each limitation on separate graphs through X-D composite formats to whatever sort of composite structure the OEM's aerodynamicists come up with when they are bored ... graphical, tabular, whatever ...

The QRH structures usually are very simplified to serve the purpose of the QRH ... quick data and assessment.

Generally, if you know what you are on about, it is not too difficult to replot etc to extract individual limits ... but it can take a bit of head scratching.

[Old Smokey]

What type of data presentation do you have Kristian17, Graphic, Tabular etc.? And what style of obstacle data base do you have - Obstacle Heights & Distances, Obstacle Clear Gradients etc.?

We'd be 'transmitting blind' in replying unless it's known what type of data availability that you have.

Regards,

Old Smokey

[mutt]

Somehow i think that the closest Kristian17 gets to a B767 is on his PC.... His knowledge of aircraft performance is almost zero!


Mutt.

[knackeredII]

To put it bluntly, if you don't know where to find the the relevant information, you shouldn't be anywhere a 757 (or any other airline aircraft for that matter!).

[Kristian17]

Sorry Mutt if i upset you by asking this question, everybody has to learn before they understand a subject. I am at school at the minute and can only learn to fly for a ppl , but i want to become a commercial pilot.

I am very intrested in aviation, therefore i ask questions on pprunes, as there are many kind pilots e.g. old smokey that are willing to teach people.

See you
Kristian

P.S: I don't really fly on FS much at all.

[mutt]

Kristian17,

Not upset, but its easier for people to answer your questions if they actually know what level of experience you have!

Mutt.

[Kristian17]

Ok , thanks mutt.

Sorry, i thought your first comment was negative.

Happy landings!

See you
Kristian

[knackeredII]

In answer to your first question, the Aircraft Flight Manual will have a Performance section which will have charts providing answers to all those questions. Any established Airline will also have a specific set of charts for the destinations they operate which greatly simplifies the calculations of MTOW/RTOW for the specific field length/obstacle clearance combination. So you start with the distances (which are known) and work out the weight, for a given set of conditions.

Hope this helps.

[Kristian17]

knackeredII, that helps a lot, i thought this must be the case. The charts must not be contained in the QRH i have. Is there anyway, i could get these charts for a 767 so i can compare it with the QRH?

Thanks for your help

Kristian

[knackeredII]

I guess you could ask for someone currently on the 767 to maybe send you a sample. Other than that it's a bit difficult to get to get hold of a copy if you're not working for an operator. My company doesn't operate them.