Originally Posted by
navigatro
USMC,
"safer" does not mean the same thing in all situations, and is subjective.
It is a statistical FACT that a reduced power takeoff (turbofan engines) lowers the risk of engine failure. In that context, it is "safer."
Of course obstacle clearance and other things are factored in the equation to determine how much to reduce the takeoff thrust setting.
Also, at very light weight and aft CG configurations, 4-engine aircraft may become (temporarily) uncontrollable with an outboard engine failure during the takeoff roll. Hence another reason to use reduced power takeoffs.
In the fighter world, AB takeoffs are indeed "safer".
Absolutely - which is why I am trying to understand the difference in what seem to be a heavy transport category aircraft procedure and one that fits across all type/model and series.
I have only flown light GA aircraft and the T-34C through Hornet in the military and I had never been introduced to reduced powered takeoffs. I would think that if it was safer to make reduced powered takeoffs because of high probability of engine failure vice the safety margin given a full power takeoff then it would seem that I might have come up against this technique sooner.
So...this seems to be a difference, so far at least since no one else from a different community has chimed in, to be a P121/heavy transport procedure.
Some of you seem to think that I am arguing against reduced powered takeoffs. to the contrary - having not flown P121 or heavy transport I don't know if it is better or worse. Just as I always do when sitting in the back I trust that the crews and procedures they are using have been vetted and found safe to operate.
I disagree with the contention that the small chance of an engine failure overrides the many safety margins that a full power takeoff gives you.
It gives me decreases takeoff distance, increased obsticle clearance, a steeper climb angle and getting me away from the ground quicker, and more thrust/speed should I have an emergency - which at least in my airplane and most others I have flown is a good thing.
Finally - though I have not seen it myself and even KC said that it was what was taught but has not seen the evidence - even if it was statistically a greater chance, my own Operational Risk Management says that I'll take the goods of a full power takeoff over the reduced power takeoff and the very small chance of engine failure due to a high power setting.
I wonder if given the oportunity - not goverened by your companies operating limitations (which are probably based on monetary savings or noise restrictions) - how many would CHOOSE a reduced powered takeoff?
Interesting discussion.
USMCFLYR
Btw - does anyone have any opinions on the failure of the double/triple checks of the numbers here? I've seen one post address this and that members procedure for backing up the numbers. What are some other techniques/procedures for ensuring good information in/good information out?