ASpilot2be
Qbicle seat warmer
We are approved for intersection departures. But us and Ravn us 7L/E in Anchorage. We can go out at max weight and sometimes reduce from there.
Full Length v Intersection Departures
- Thread starter AA34
- Start date
z987k
Well-Known Member
I think you'd be hard pressed to find an operation that is prohibited from doing them. If you can't run the numbers you should have never made it to the cockpit.
Roger Roger
I am le tired
I think what I'm seeing here is a big divide between small airplanes (especially piston singles) and part 25 turbine aircraft.
Nick
Well-Known Member
That logic is backwards.
Full length would result in de-rating rather than being anywhere near TOGA power, and the chance of an engine failure would be reduced by taking full length.
Additionally, some engines which are maintained on a "power-by-the-hour" program might prove to be more economically operated by taxiing 2 minutes up the hill to save from doing a full power takeoff.
I think the key thing in this whole discussion is that there are really two types of intersection departures.
One goes from "plenty of runway" to "still plenty of runway."
Another goes from "plenty of runway" to "thousands of feet less runway."
No one really knows for sure what the other airplane you're observing is in. SWA with 5,000' of runway behind them could have been on a repo flight to DAL and in that case 7,000' available would still be in the "still plenty of runway" category.
Just opinions, judgement calls, and nothing in black&white with this topic.
The way I think of it though, is that I'm fine with an intersection departure if it still feels like there's plenty of runway. That may mean tossing aside the numbers for an intersection departure way down the runway and sticking with full length, even if the airplane can do the short field version.
Seggy
Well-Known Member
It doesn't work like that either.
If we already have the numbers, and it's prudent considering the conditions and we've talked about the possibility of an intersection departure, it's not that big of a deal.
If we've got to send off a TOPR for a last minute intersection departure instruction and we don't have time to carefully look at it, the time saved isn't worth the increased threat.
Taking off without performance data in an Airbus is literally something you don't want to experience.
If we've got to send off a TOPR for a last minute intersection departure instruction and we don't have time to carefully look at it, the time saved isn't worth the increased threat.
Taking off without performance data in an Airbus is literally something you don't want to experience.
Qatar likes to do intersection departures in MIA.
Hey, HEY! The CEO says that happens like ALL the time. It's no big deal.
Toobdrvr
Estrellas Asesino
Nick, I respectfully disagree...
While I follow your logic, I don't believe this is factually supported.
This is true. However this is not the concern for most of the "Full length or bust" guys I've encountered.
While I follow your logic, I don't believe this is factually supported.
This is true. However this is not the concern for most of the "Full length or bust" guys I've encountered.
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Toobdrvr
Estrellas Asesino
Personally, we either have good numbers, which comply with FAA, Company, and Industry practices and procedures with an adequate safety magin, or we don't...
I prefer to stick with cold numbers and proven performance and procedures over feelings, but hey, If we're flyin together and you would prefer to go to the end, no prob. Let's just try not to miss anything while one of us is heads down trying to get new numbers (Fifi will only let you have one solution per runway).
Sorry I'm not very good with multi-quote.
jtrain609
Antisocial Monster
My understanding is that what Nick is saying IS factually supported. Engines don't blow up at V1, they blow up at the application of takeoff power, or in the alternative, when you select climb thrust. If you did a flex takeoff, then your climb thrust will commonly be above your takeoff power, and that's when the engine decides to knock off for the day.
I've been taught this as long as I've been flying turbine engines around.
Toobdrvr
Estrellas Asesino
In the 10 short years i have been flying a CFM-powered A320 (as well as the 10 prior years in turboprops), climb thrust has always been less than takeoff thrust. Even in flex.
That's why it's called "Thrust REDUCTION / acceleration altitude"...
I too belive that engines are more likely to fail at initial power up. I just doubt that evidence supports an increased rate of occurrence with flex vs TOGA. Just a guess on my part. I wouldn't know where to look.
That's why it's called "Thrust REDUCTION / acceleration altitude"...
I too belive that engines are more likely to fail at initial power up. I just doubt that evidence supports an increased rate of occurrence with flex vs TOGA. Just a guess on my part. I wouldn't know where to look.
Toobdrvr
Estrellas Asesino
BTW, the "Beer Winner" info might be found here:
http://www.faa.gov/aircraft/air_cert/design_approvals/engine_prop/media/CAAM2_Report.pdf
(I was bored).
Haven't had a chance to read it yet...
http://www.faa.gov/aircraft/air_cert/design_approvals/engine_prop/media/CAAM2_Report.pdf
(I was bored).
Haven't had a chance to read it yet...
BobDDuck
Island Bus Driver
A 60 degree flex with no derated climb setting on the BR725 717 will give you a power increase at the changeover from to to climb power.
Really? We derated almost all the time in the -95. Granted we aren't carrying a whole lot of gas normally.
Autothrust Blue
“If you jump on my shift, that’s just rude, man.”
It is also supported by experience and by a rather nice gentleman from GE who was good enough to come over and give us quite a nice talk about their engines.
And LOL at anyone who shuts a CF34 down for JUST high N1 vibrations with no other indications, on the same note. (Your AFM procedures are controlling etc.)
ASpilot2be
Qbicle seat warmer
In the SAAB we can reduce as low as 76%,but at 1000 feet we set the power to 100% or whatever the chart calls for.