Hello to all, I know the procedure for take-off is in the PIC manual. What it does not say is why we have to apply power to 70% N1, wait until it stabilizes, then hit N1 on the MCP. Every time I do it this way I loose at least 1000 ft of runway just waiting for that N1 gauge to reach 70% N1...Is this the way its done on the real aircraft, is that what a rolling take-off is? If you were at LGA you would end up in the water! I never noticed the real 767 waiting that long until thrust was applied as it felt continuous. Are the brakes held in until the engine stabilizes at 70% then take-off thrust applied? Remember that saying, One of the most worthless things in aviation is runway behind you! :-wave Thank you

Please someone correct me if i am wrongTo the best of my knowledge, the water at the end of the runway is not a place anyone wants to take a dip... Application of power should be done smooth and evenly. At a standstill, waiting for takeoff clearance or what not, the N1/EPR button shouldn't be used. The rate at which the throttles are advanced cause, heres the term im unsure about, compressor stalls. You have to get the airplane moving before you go to full thrust. I think that is why in the manual it says to apply 70% power before going full bore... The best way to get around this I am told is to get the aircraft rolling, "stand the throttles up", accelerate then hit the N1/EPR button.. Then you must take into account this should all be accomplished in time for the throttles to be set at max power before 80 knots where the Throttle Hold indication should appear on your Flight Mode Annunciator. Which is either at the top of the ADI(Pegusus) or the bottom.

Applying full takeoff thrust at 0 knots airspeed will NOT cause compressor stalls (as long as its working properly). An engine like that would never be certified!Compressor stalls can occur if you use max reverse thrust at low airspeeds, but that's a different story.The reason why you accelerate the engines to 70% N1 before hitting the N1/EPR button is to make sure both engines are accelerating evenly. A turbofan engine takes quite some time to rev up from idle. In case one engine lags behind, the other engine may already reach takeoff N1 if the N1/EPR button has been pressed, causing quite a lot of differential thrust. On a slippery runway, you may actually roll off the runway!If I remember correctly, in the first version of 767PIC, the engines took ages to accelerate. Boeing says that if takeoff power is not set by 80 knots, you should abort. With 767PIC v.1.0 you were always destined to abort. The airfile update fixed this, I believe.Anyway, in real life it takes around 1 to 2 seconds to get from 70% to max power and let's say 3 seconds to get from idle to 70%. So you shouldn't lose 1000ft using the 70->N1 techqnique.Regards,Mark

>The best way to get around this I am told is to get the aircraft rolling,"stand the throttles up", accelerate then hit the N1/EPRbutton..Does that mean we have to wait until the thrust reaches 70% before hitting the N1 button? Or we can just advance the throttles until we see the white thrust arc around 70% N1 then hit N1? Thank you for the reply

"Does that mean we have to wait until the thrust reaches 70% before hitting the N1 button?"Exactly. Otherwise, if you just advance the throttles further, you are not making sure that both engines are accelerating together...

Just to tag along...There is also limitations to take into account the lenght of the runway and the conditions encountered during the take-off and climb-out segment of the aircraft. Part of that is the performance of the aircraft/engine acceleration. This may result in assumed temp take-offs, flap setting requirements, weight reduction etc as found in the airport-runway analysis.Some airports such as LGA/DEN/SBA will have all sorts of performance restrictions based on unique circumstances of operating in/out of them and are noted either in the "T" pages (published by the aircarrier engineering/operations/flight departments) or on the release.Compressor Stalls can come about from many different areas...any serious disruption of the smooth ingestion of air can set-up a compressor stall. A bird ingestion, the very odd "burble" of air due to a crosswind blast, thrust reverse all can create that bang that gets your attention real quick. You will also see some notations in the manuals saying point the aircraft into the wind if possible on start-up. Some of the earlier engines didn't like a breeze up the bum prior to light-off.Part of the object in throttle "stand-up" is to make sure you have the air smoothly going through the engine before "pouring it on". Even in a/c not equipt you'd want to stop to make sure you have smooth and somewhat equal performance prior to advancing to take-off thrust. Otherwise as stated earlier you can end up going where you didn't want to.Tim__757

>Or we can just advance the throttles until we see the white thrust arc around 70% N1The white arc is basically showing you where your thrust levers are... not what your engines are doing ;-) Cheers.Ian R>