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Prop a/c @ major airports: Intersection T/Os the norm?

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Ummm...this sounds a really silly question but I just had to ask it http://jm.g.free.fr/smileys/cute_smileys/ermm.gifAt really busy airports (O'Hare, Heathrow ,Hong Kong etc.) are the pilots of turboprop/piston/STOL planes such as Saab 2000, Caribou, ATR, D328, ATP & Fokker 50 usually directed by ground control to perform an intersection depature to speed things up (because those planes need much less runway than the heavies)?I know theres nothing more useless on the ground than runway behind you & that the Captain has the last word but do controllers generally direct such planes to do intersection departures instead of full-length?Would be interesting to me to hear about this...and any real-world prop drivers out there...would be great to hear from you.Thanx http://jm.g.free.fr/smileys/cute_smileys/smile1.gif

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Donny AKA ShalomarFly 2 ROCKS!!!I am not a real world pilot, but I play one on the internet... sorry. From what I have read and heard, intersection takeoffs can be initiated by either ATC or the pilot, however it is the full discretion of the pilot in both cases. He/she can decline an intersection takeoff. Wake turbulence as well as time saved can be a factor in requesting them, since wake turbulence dissapates once a plane is on the ground. Best Regards, Donny:-wave

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Intersection takeoffs for smaller aircraft at big airports can be problematic if you are departing behind a heavier aircraft since it puts you further down the runway and closer to the wake turbulence. I had a tower controller tell me that an intersection departure would necessitate a 2 minute delay, but if I did the full-length takeoff I could go right away.When landing at big & busy airports, a long landing with an early turnoff is often preferrable for lighter aircraft.Some airports prohibit intersection takeoffs at certain times, presumably to reduce the chance of runway incursions.John

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Donny AKA ShalomarFly 2 ROCKS!!!I should have been more specific about when planes are landing versus taking off. But if you are numer two behind a heavy taxiing to the runway 5 minutes after the last heavy (can happen at airports like KABE) an intersection takeoff before they get to the active could be an attractive option.Did you mean "short landing early turnoff"?Best Regards, Donny:-wave

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Okay, here is what I see at KDFW when spotting every couple three weeks.The SF340's start their takeoff from the same point as the regular regional jets and long haul jets at the end of the runway.Normally they like the turbo props to land on a different runway than the jets, but there some mixing of jet and turbo prop traffic almost all the times.It's really funny to watch the turbo props cross the airport fence at 150 kts when they are in the same pattern as larger jets. Looks like they are going to strafe the airport.When using the same runway as the jets, the turbo props will normally cross the threshold at about 500 ft AGL. So they land 2-3,000 ft farther down the runway than the jets. Might keep them above the roughest air - I don't know.I've never seen the turbo-props takeoff behind or land behind a heavy. If a B777 takes off on 35L, the turboprop will takeoff on 35C, the same with landing. The turbo props will follow MD-80, B737 and A320 sized aircraft on the same runway. RJ's don't even follow B757's.The only real intersection takeoffs I've seen / heard on the scanner - have been light GA from Taxiway A3 on 31L. Cessna's & light twins - that size aircraft. Doesn't happen often because not that many aircraft of that size visit the airport. I once heard a Skylane cleared to use Taxiway WL for an intersection takeoff on 18L.It appears that maintaining ground traffic flow smoothly is more important than the minute or so an intersection takeoff might save.However, having said that - remember that KDFW is a real world airport and what I see / saw might not be the practice an hour later.

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Donny,Smaller aircraft need to land beyond the touchdown point of a heavier aircraft for wake turbulence avoidance. Add to this the fact that turbo-props can make dramatic, last-moment speed reductions, especially when they are carrying freight instead of passengers. That means a long landing and an early turnoff (to avoid wake and minimize time on the runway) is often desirable for smaller, turbo-prop aircraft.My experience being number 2 behind a heavy is that the heavy takes off first because if they are in front of me, they probably got their clearance before me, they'll get their IFR release before me, and they'll depart before me. Besides, they burn more fuel.John

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Flow of traffic is vital, especially at large airports. At Schiphol most aircraft get intersection takeoffs, sometimes even 767s and 777s.Of course our runways are 11000ft or so long, plenty enough for all but a heavily overloaded 747 in most weather conditions, so there's really no need to use all the runway for most aircraft at most times.By using intersection takeoffs, taxi times can be greatly reduced and the lineup procedure smoothed out.At times there can be 3 or even 4 aircraft lining up at once, staggered so the largest one has the most runway to use and (thus) starts last leaving the smaller ones with no wake turbulence to worry about.Were these to all be assigned the entire runway, precious minutes would be lost. At an airport that during departure peaks sees one aircraft depart from each of 2 departure runways every 30 seconds, that can run into serious delays.I'm not so sure if the flightcrew even has final say in this. I've heard requests for different (longer) runways denied even if those runways were open at the time for example.But of course most pilots would elect an intersection takeoff if they could get one if it would save them time, and that's exactly what it can do.ATC knows aircraft weight and performance data and won't assign an unsafe runway length, so unless you've reported a too low weight you should never have trouble with the shorter runway length assigned to you.

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Where did you get the idea that ATC knows each aircraft's takeoff weight and performance?Maybe things are different in Europe, but in the US the flight crew is responsible for determining takeoff and landing performance. They tell ATC what they need, not the other way around. If a pilot is given an intersection departure and the runway length available is insufficient, the pilot in command will tell ATC "unable."In the US, the regs say "The pilot in command of an aircraft is directly responsible for, and is the final authority as to, the operation of that aircraft."Flow of traffic is important, yes, but it never trumps safety.John

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Indeed, safety first. ATC knows aircraft performance data. They have the type which gives them a maximum weight.That in turn gives a maximum required runway length, it's that simple.ATC is boss, always. If they tell you to go somewhere you'd better do so or you're facing investigation and possible loss of license. Pilot may refuse to accept a short runway, but it will be expensive as they're liable to loose their slot and at the very least will be delayed as they're stacked at the end of the takeoff queue.I've in several years of listening in to ATC here never once heard that happen.I've heard aircraft request a longer runway (not a different intersection) for takeoff when contacting clearance delivery (who here assign takeoff runway, but not the intersection to use) once or twice, which requests were always denied.In all cases these were SIA 747s, which always leave at near maximum weight (or overweight, I suspect). They're always asking the longest available runway even if they know full well that one isn't open for takeoffs.I've heard an aircraft requesting a different landing runway once, to save on taxi time (they were seriously delayed). That one was granted, all it took was assigning a different parallel runway.

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In my commercial flying getting or even hearing assigned intersection departures is pretty rare (at least at the airports I frequent). In most cases when it does occur ATC asks if you can accept an intersection departure (BTW some company op-specs forbid intersection departures period). They usually don

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If only calculating takeoff performance were that simple. There are several factors that determine takeoff performance and weight is only one of them. That's why this calculation is done by the flight crew, not ATC.I think you have a basic misunderstanding about ATC always being the "boss." In the US, as evidenced by the regulation I cited (14 CFR 91.3), the PIC can refuse a clearance and I have on several occasions in my flying career. ATC isn't flying the plane, the pilot in command is.I'm curious, is your experience as a pilot or as someone who listens to ATC communications on a radio?

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In my experience ATC do not usually issue an intersection departure to an aircraft without the aircraft requesting it. I issue full length to all aircraft unless they request an intersection departure, or unless there is an established procedure or agreement for aircraft to take an intersection departure, (usually due to taxi times.) ATC do know the MTOW of an aircraft for wake turbulence requirements but that is not used to 'make' an aircraft take an intersection departure. Having said that, intersection departures are sometimes offered for expedition, usually with the remaining runway length included in the offer.Mike

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Come to Schiphol, intersection takeoffs are the norm here rather than the exception.There may be an F50 at S4, an F70 at F5, a 737 at F6 and a 777 at F7 (which is the full length), all waiting for whomever is rolling to get past their intersection to line up.Taxi instructions include the intersection, these are not mentioned in the clearance delivery.

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>Come to Schiphol, intersection takeoffs are the norm here>rather than the exception.>There may be an F50 at S4, an F70 at F5, a 737 at F6 and a 777>at F7 (which is the full length), all waiting for whomever is>rolling to get past their intersection to line up.>>Taxi instructions include the intersection, these are not>mentioned in the clearance delivery.Whether you are given instructions to an intersection or full length to depart depends on the particular layout of an airport and how the ATC people at that airport like to flow the traffic there. At some airports, you would hardly ever see anybody use an intersection. At some airports, you would see people use intersections all the time. However, no takeoff accomplished under most commercial regulations can be done without having checked takeoff data. The takeoff data is available in a cockpit manual or electronically transmitted from dispatch specifically for each runway or each runway intersection takeoff. For example, at Chicago O'Hare, an often used intersection departure is Rwy32L at T10, which is available in the takeoff data of our planes so that we can do this if assigned. If they gave us Rw32L at T9, we would have to respectfully decline since there is no Rwy32L at T9 intersection page in our books.So at Schipol, it means that those intersections are common procedures for that airport and the airlines that use Schipol would have had their engineering departments provide takeoff data for all those intersections. So this is something that is specfic to the airports, the airline and the type of plane.To get in an argument about whether airports "normally" do intersection departures is kind of dumb because it may be normal here and not normal there. So what we have is some guy who lives near schipol arguing it is normal while some guy living by la guardia argues it is not normal.

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Agreed and thanks for describing/writing that better than I ever could!

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Wow what great responses to my question - thank you all very much :) Interesting to see how its a regular occurence in some countries but not in others. The bit about taxiway departures was cool - I didnt know those even happened! Makes sense though for small planes at massive airports. I also did not know that the level of detail FMS systems held - down to airplane performance from X intersection @ X airport! Impressive! The wonders of computers.About wake-turbulence....correct me if Im wrong but planes like Fokker 50, Caribou etc...if they drop lots of flap and then depart they can climb more steeply than a jet right....and so get above and well away from a preceding heavies vortex?

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