LOng Range Cruise?
 

Can anyone give me some info on how Long Range Cruise figures are produced? I am getting very confused so some basic definitions would help.
Thanks
bertie

Cost of fuel vs Cost of time = LRC speed

all calculated via the the cost index entered:ok:

Long Range Cruise (LRC) speed is calculated as a speed faster than Maximum Range Cruise (MRC) speed that has 1% worse range performance than MRC.

Your airplane will exhibit better speed stability flying at LRC rather than MRC. This is the reasoning behind the LRC definition.

Are you sure about that? LRC is a speed not affected by cost index as it is 99% best range under still air conditions.

Ignore Mopnarch Mans answer, its totally incorrect! He has actually explained ECON SPEED.

For a given weight/altitude, you will get a Maximum Range Cruise Speed where you obtain the greatest number of nautical miles per unit of fuel, in order to obtain flight stability, this is reduced by 1% to give Long Range Cruise.


Mutt

Regarding the comments about MRC being an unstable speed, and how this is improved by flying 1% faster -

I know that piston engine aircraft fly at MRC at minimum drag speed, which is speed unstable. But I thought that MRC speed for turbojet aircraft, was the minimum value of drag / TAS, which is a stable speed.

Where have I gone wrong?

True statement. LRC isn't effected by cost index when LRC is selected. However, climb and descent speeds will be effected.

In addition, while flying in LRC v. Econ, your IMN will not change as it does in Econ with respect to a headwind/tailwind.

This really is quite worrying when Monarch Man might well be presumed to represent quite a few new(er) folks at the pointy end, who truly do believe everything that comes out of the FMS/FMC, no matter how unusual, is positively correct.

What do they teach these folks in ground school, one wonders?

Thankfully they are labelled such

<ECON

<LRC

So be be frank 411A..what does it matter? We follow company SOP's

(happy to hold my hand up regarding my mis-definition..however having gone back over my manuals..I am now fully apraised:O :\ :ooh: :ok: )