Fdm galore

[KL-666]

Lately i have noticed that many (young) people have grown into being very knowledgeable about how an aircraft moves through the air. I wanted to name a few, but then i would forget so many others, so i do not. Just a nameless example. Question: Why can't i climb 3000 ft per minute above fl 300, please fix it? Answer: Sorry, that is reality, low climb rates happen due to thin air. Such are the correct knowledgeable answers of the (young) people nowadays. Earlier you could expect an answer of a self proclaimed know-it-all person like: Ow, i'll fix it, that you can climb 3000 ft per minute above fl 300, my mistake that you could not. Just imagine the havoc that used to cause to fdm's.

Having these knowledgeable (young) people around is a great asset to the potential quality of flight dynamics. It gives confidence for a future with better fdm's.

Kind regards, Vincent

[KL-666]

1. I looked on the forum and the wiki, and people have been saying that the correct way to engage TO/GA on the runway is by pressing either ctrl-t or 'd'. I'm on a mac, and when I tried both of these methods, nothing worked.

https://forum.flightgear.org/viewtopic.php?f=4&t=21870&p=319148#p319148

OMG, again those self proclaimed know-it-all "people have been saying".... I am sure most of the (young) people i mentioned just now know better. For those who do not, the correct answer is in here:

http://avherald.com/h?article=49c12302&opt=0

Kind regards, Vincent

[Omega]

He was referring to applying TOGA thrust in order to carry out a derated takeoff... Not a go around.

[KL-666]

The texts of manuals can be woolly. But it boils down to simply: Under no circumstance can toga be invoked while on the ground.

Kind regards, Vincent

[Omega]

The TOGA button can perform two completely separate functions depending on the phase of flight the aircraft is in. (1) During the takeoff, the pilot in command will manually set the thrust levers to 40% N1 and check that both engines are spooling up simultaneously and are stable. If so, he will press the TOGA button which will automatically push the levers precisely to the selected derate configuration. During takeoff, manual thrust in lieu of TOGA mode is only used in very rare circumstances.

(2) At any point during the approach phase, TOGA can be used to set go around thrust. However, once the aircraft touches down, TOGA is inhibited to prevent the pilot from pressing the button by mistake during landing. This is what the accident report was referring to.

An automatic go around is not available any time after the aircraft touches down during landing, because the TOGA switches will be inhibited. If a go around is required after touch down, it must be performed manually, without flight director guidance. The TOGA switches become active again shortly after the aircraft becomes airborne again.

[KL-666]

As i said, the texts of the manuals can be woolly. They seem to state that some madman may be able to invoke toga on take off. But at better reading that is not the case. Unfortunately i am not going to look up that woolly stuff again. The basic rule against crashes and crazy take offs is still: Under no circumstance can toga be invoked while on the ground. That is the essence of the manual's statement. And if you want to fight with woolly words and crash, that is your business. Wise airlines instruct their pilots differently.

Kind regards, Vincent

[Omega]

All wise airlines I know of that operate Boeing aircraft, use TOGA during takeoff to prevent engine wear. This is completely normal, common practice.

[KL-666]

You are technically right that you may use toga on take off. An essential part of it is to have your fms programmed correctly. Else the a/t system does not know the desired throttle setting.

Btw. I have never heard a pilot stating he uses it for avoiding wear. If he does it, he does it out of laziness after having worked so hard on the fms. He does not want that work to go to waste.

Edit:
The thing is, that if after calculations the take off throttle should be e.g. 80%, it makes no difference whether you advance the throttles yourself to 80% or that you let that do by toga. The wear is no different.

Kind regards, Vincent

[Omega]

Modern aircraft flight management computers will determine the power needed by the engines to take off, based on a number of factors such as runway length, wind speed, temperature, and most importantly the weight of the aircraft. In older aircraft these calculations were performed by the pilots before a takeoff. The advantage of having such a system is the ability to reduce wear and tear on the engines by only using as much power as is actually required to ensure the aircraft reaches a safe take off speed.

The FMC will calculate a very precise N1 percentage that maximizes safety and efficiency. For example, 90.7% N1 which would be really hard to precisely set manually without an FE or FO helping you push the thrust levers while they closely monitor N1. However, the TOGA mode knows exactly where to put the thrust levers in order to achieve 90.7%.

[KL-666]

I'm sorry, you may have missed the edit on my previous post. The N1 is perfectly readable on the engine display.

Edit:
And btw, i do wonder whether people who are not able to advance throttles to a certain setting reasonably precise should be at the pointy end of the aircraft at all.

Kind regards, Vincent