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Prop Jet Take-off From Mid-runway?
Posted: Sun Apr 27, 2003 5:28 pm
by United777
Hi all
I was just wondering why prop aircraft like the Q300 or Q400 have to go to the end of the runway to take-off when they need just half the runway most of the time. I was flying from
SEA-
BOI on a Q400 and we had departed from RW16L in Seattle. We taxied for about a few minutes but while doing so I was just wondering why these small regional aircraft can't get clearance to depart from the middle of the runway. Is it more of a safety issue these small prop jets can't do so.
RE: Prop Jet Take-off From Mid-runway?
Posted: Sun Apr 27, 2003 5:44 pm
by 744rules
runway lenght is useless when it is behind you in case of emergency
RE: Prop Jet Take-off From Mid-runway?
Posted: Sun Apr 27, 2003 8:55 pm
by Airbus Lover
Yup 744rules is correct. In case of a RTO (Rejected Take Off) you would need runway length. and If you did an interesection take off, you might not have enough time to stop even though you might be far before V1 and have no choice but to rotate!
RE: Prop Jet Take-off From Mid-runway?
Posted: Sun Apr 27, 2003 9:22 pm
by L-188
I don't belive any ATC will tell you to take-off mid-field.
That being said, I have heard them politely ask if it was acceptable.
Up here in
ANC......
Often the Medevac flights, (Metro, Merlin, King Air, Lear 25 and 35) will go ahead an launch out of 24L at Foxtrot or Echo, which is the entrance to South Airpark where most are base.
Just saves that much taxi time, and they don't need that 1500 feet or so, they still have something like 8500 to play with.
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon Apr 28, 2003 1:41 am
by avt007
Mid field T/O is quite common at
YVR for Dash 8 100s, and 300s on runway 26L.
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon Apr 28, 2003 1:44 am
by ScooterTrash
I personally don't like intersection takeoffs with allot of runway behind me. I have to think, how would it look in the accident report if something went wrong? I like to have lots of pavement to deal with a problem on the ground, even though I fly an airplane that is a really good short field performer.
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon Apr 28, 2003 3:03 am
by VIflyer
More than likely Horizon doesn't have the take off performace charts for a mid-runway takeoff out of
SEA. I know in
ORD depending on the winds, they use rwy 32L from taxiway T10, which is only 3/4 of the runway (8800 Ft available I think), and the only way we can do that is that we have the performance charts for rwy 32L for the whole length and from T10 for the EMB.
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon Apr 28, 2003 3:06 am
by ben
"There is nothing as useless as runway behind you" .. that goes for both takeoffs and landings.
Along the lines of what Scootertrash says, how are you going to explain it to the owner when you give them back a bent aircraft?
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon Apr 28, 2003 3:07 am
by sllevin
I've seen a few instances where operating specs allowed for intersection takeoffs as long as 9000' was still available.
This was to specifically deal with some 14 and 15 thousand foot long runways -- in short, it was felt that constantly taxiing another mile would in the long run create more wear and tear and potential hazard than by operating off of 9000 of runway (this was with Beech 99's). It was always PIC's discretion,though.
Steve
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon Apr 28, 2003 11:10 am
by ScooterTrash
In the airline (
FAR part 121) world it is pretty easy to decide whether to perform an intersection takeoff. It is not even legal unless you have specific performance numbers for that intersection which tell you it is ok to go at your particular weight.
Even if I have the numbers, I usually try to talk the captain out of intersection takeoffs with substantial runway behind me. "Hey, we get paid by the minute, and going to the end will be worth at least .1!" I usually say.
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon Apr 28, 2003 11:35 am
by AJ
As V1 cannot exceed rotate in a transport category aircraft once you rotate you are committed to flight, insurance company lawyers would tear you to shreds if you aborted after this point and put the aircraft back on the remaining runway unless a greater emergency existed.
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon Apr 28, 2003 12:01 pm
by wagz
If I'm not mistaken, I remember seeing Dash 8s and other props depart runway 35 at
PHL from taxiway K, leaving them maybe 4500 to 5000 feet (Runway is only 5459 feet total). I'm assuming this done so departing aircraft don't intefere with 27R arrivals, as the 35 threshold is just beyond the intersection with 27R. Arrivals on 35 crossing in front of arrivals on 27R can get hairy sometimes, as I've seen many go-arounds and even last minte 90º left turns by 35 traffic to land on 27L (traffic permitting).
Joe Wagner
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon Apr 28, 2003 12:23 pm
by ScooterTrash
Wagz:
You are not mistaken... We do that in the dash all the time. It is not always possible in the -300 series, especially if it is warm. I don't have a problem with it in the "short" dashes because 500' is really not an appreciable amount of runway for a Dash 8.
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon Apr 28, 2003 9:48 pm
by 2000first
I have been on a
BMI 734 that took off from half way down the runway at
BFS. There were only about 30 passengers on board at the time and we seemed to take off pretty quickly. For those of you who are familiar with
BFS we started out take off from the poibt directly opposite the viewing gallery, which i am sure is exactly half way down the approx 9000ft runway!
RE: Prop Jet Take-off From Mid-runway?
Posted: Tue Apr 29, 2003 9:05 am
by POSITIVE RATE
On my last flight
ADL-
MEL on a
DJ 737-700 we did an intersection departure from hold point D1 runway 23. I was amazed that the 737 could take off in such short a distance and this was in summer with about an 80% load capacity on board. Total runway length is 3,100 metres, so i guess we would have taken off at about the 2,000-2,500 metre point. I've also seen other 737
NG's doing the same.
RE: Prop Jet Take-off From Mid-runway?
Posted: Tue Apr 29, 2003 10:39 am
by 411A
The airport authority is many times the regulating authority as regards intersection takeoffs, generally due to noise considerations.
The FAA will approve providing takeoff performance is available for the operation of the respective airline.
For example, PSA many years ago very often departed mid-field with Lockheed Electra aircraft from 25L/R in
LAX, because the FAA approved, takeoff performance was available, and the LosAngeles Department of Airports also approved the operation.
RE: Prop Jet Take-off From Mid-runway?
Posted: Fri May 02, 2003 1:52 pm
by jetskipper
At
CLE it is pretty common for all aircraft including mainline aircraft to depart from 24l at intersection N or
6L from W, but as previously stated we are given the performance charts for that specific intersection and have the required start-stop distance plus a large buffer.
Intersection Departures
Posted: Sat May 03, 2003 6:50 am
by musang
On the jumpseat of a SAA 743 about 18 months ago, Cape Town to J'burg, we were no 3 to leave the ramp behind a 732 and a 722, which both turned left and went to the full length. We just headed straight from the ramp out to the runway, turned right and launched southeast bound. Airborne in about half the runway remaining, very impressive.
Don't have any
CPT charts to hand so can't quote distances, but any aircraft's performance is going to be good with less than half a pax load and minimal fuel (it was replacing two 737 flights).
I'm a firm believer in runway behind being as useful as fuel in the bowser and altitude above you, and will always take full length unless there's an considerable performance surplus.
Regards - Musang
RE: Prop Jet Take-off From Mid-runway?
Posted: Sat May 03, 2003 8:13 am
by jhooper
Call me paranoid if you want, but I don't even do intersection takeoffs in my Piper Cub anymore. I take every piece of pavement they'll give me. The cub doesn't even need 1000ft to takeoff, but if the runway is 14000ft, I'll take every bit of it. If the engine quits, it gives me far more options and margin of safety. And I'm part 91, so I basically make up my own rules.
RE: Prop Jet Take-off From Mid-runway?
Posted: Sat May 03, 2003 4:31 pm
by justplanesmart
I know that Horizon Air used to have their DHC-8-100's take-off from the intersection at
SEA frequently. However, after the USAir/Metroliner collision in 1991, there were restriction placed on intersection take-offs, although these were primarily nighttime/low-vis situations, as I recall. It maybe that some airports have chosen tighter rules, or it might be that the DHC-8-Q400 needs more runway.
RE: Prop Jet Take-off From Mid-runway?
Posted: Sat May 03, 2003 5:02 pm
by ha763
I'm pretty sure IslandAir and Pacific Wings do intersection takeoffs on
8L from Lima in
HNL during regular tradewind weather. I also remember seeing a Pacific Wings Caravan takeoff from Lima during kona weather.
HA's 717's and
AQ's 737's also do intersection takeoffs on 26R from Echo during kona weather. But then,
8L/26R is 12,357 ft long and taking off from Lima would probably give you somewhere around 7000 ft in the
8L direction and over 5000 ft in the 26R direction, which should be more than enough for the Dash 8 and Caravan. Both planes and the 717 fly to Molokai where the main runway is only 4494 ft long. From Echo, you have about 10,000 ft of runway and the 717's and 737's are off the ground by about Lima, so they even have a lot of space if they do a RTO.
I can probably guess that IslandAir and Pacific Wings do intersection takeoffs to ensure the proper spacing from landing planes and the interisland jets due to their slower speed.
RE: Prop Jet Take-off From Mid-runway?
Posted: Sun May 04, 2003 1:26 am
by JA54123
At my hometown airport,
AMA (Rick Husband Amarillo International Airport in Amarillo,
TX--
http://www.amarillo-cvb.org/airport.html ), I have seen mid-field takeoffs quite a few times. The runway is 13,502'x300' & the only airline that does these type of takeoffs is Southwest. American Eagle (ERJ145), Delta Connection(CRJ200), Continental Express(ERJ145) & United Express(Beech1900) all seem to always taxi to the end of the runway and use the full thing, usually lifting off less than halfway down it. Southwest on the other hand will taxi from the terminal, which is located at approximately midfield, straight to the runway and take off from there with their 737s of various types. As I have been flying on these Southwest aircraft a few times when they took off midfield & I kind of wondered about the safety of taking off on a hot July day in a 737-200 fully loaded from this point, but it seems to work.
RE: Prop Jet Take-off From Mid-runway?
Posted: Tue May 06, 2003 10:56 am
by L1011
When I was in Frankfurt, Germany, in the sixties, Lufthansa Convair 440s often took off from the middle of the runway, but other prop planes such as Turkish DC-7Bs and KLM Electras didn't.
Bob Bradley
Richmond, VA
RE: Prop Jet Take-off From Mid-runway?
Posted: Wed May 07, 2003 4:05 am
by Guest
Intersection takeoffs are against my airline policy, and my own... under all circumstances, and even when I flew for other companies, I always took full length of the runway... even if the company permitted intersection takeoffs...
xxx
When I train pilots on the line, I INSIST that they line-up on the runway with a MINIMUM amount of runway length wasted to do so... A tail which is above the "grass" when lined-up, brings a big smile on my face...
xxx
... besides, I am paid by "block time"... I taxi slow, and go "to the end"...
(s) Skipper
RE: Prop Jet Take-off From Mid-runway?
Posted: Fri May 09, 2003 5:38 am
by Jj
Skipper
You may have a point in your last comment!
At least I'm sure that Aerolineas does use the whole runway! =) I actually hate intersection take-offs... plus it brings up a new thing: If an accident similar to MJ3142 back in 99 should happen again, but the pilot had been taking off from an intersection, I'm sure I wouldn't be happy to say the least...
RE: Prop Jet Take-off From Mid-runway?
Posted: Fri May 09, 2003 6:22 am
by RightWayUp
What is wrong with intersection departures? If you take full length you will only reduce thrust more, and probably end up losing an engine at V1 in the same position as if you had taken the intersection.
RE: Prop Jet Take-off From Mid-runway?
Posted: Fri May 09, 2003 9:53 am
by Herman
In Singapore Changi Airport(WSSS), the ATC cleared a prop plane for take-off using half of the runway but instead it turn into the wrong direction for take-off and immediately ATC cancelled take-off clearance. By the way, there was a plane on final 6miles.
Herman
RE: Prop Jet Take-off From Mid-runway?
Posted: Fri May 09, 2003 10:26 am
by ScooterTrash
RightWayUp:
What is wrong with an intersection takeoff is that anytime you leave runway behind you are eliminating options in an emergency. Most turboprops do not use reduced power settings for takeoff, so the reduced thrust argument is moot.
RE: Prop Jet Take-off From Mid-runway?
Posted: Sat May 10, 2003 11:11 pm
by XXXX10
I bet no-one has ever seen an A340 do an intersection take off
RE: Prop Jet Take-off From Mid-runway?
Posted: Sat May 10, 2003 11:17 pm
by L-188
I caught the first minutes of an intersection takeoff of a China Air A340 here in
ANC.
Unfortunatly rather then turning right to go up runway 32 here, the pilot, how was apparently Blue-white colorblind, chose to use Taxiway K for takeoff.
He got it off, but dragged the mains through at least one berm on his way out of here.
RE: Prop Jet Take-off From Mid-runway?
Posted: Sun May 11, 2003 2:02 am
by Rick767
"What is wrong with intersection departures? If you take full length you will only reduce thrust more, and probably end up losing an engine at V1 in the same position as if you had taken the intersection."
RightWayUp is actually spot on here. In our company we always derate takeoff thrust wherever possible. On a typical flight to Palma from a 10,000ft runway we might be able to fully derate the thrust on takeoff (i.e. to the maximum permitted level, about 75% of max thrust).
Now our airline does not allow derated take-off thrust settings to be used when making an intersection departure (for one, it would be too time-consuming for them to create take-off charts for every intersection and then calculate derate allowances, so it's easier just to publish full-thrust tables for intersections).
This means on a flight from say Manchester to Palma, a full-length take-off with max derate will see us hit V1 perhaps 7,000 to 8,000ft down the strip. If we accept a take-off from "Juliet Alpha", the first intersection down 24R, we have about 9,000ft runway ahead of us. With a full thrust takeoff (mandatory from an intersection) under the same conditions we will be off the ground just over half way down the runway, probably climbing through 300ft over the point at which we would only have just hit V1 on the full-length take-off.
So not a big concern for us departing from an intersection, often it is imperative to get us out ahead of the queue (for slot reasons). Turboprops depart from that intersection at Manchester all the time, because otherwise they'd be waiting with all the jets for full length and also pick up a time delay for wake seperation. Why do that when you can jump off ahead of them?
RE: Prop Jet Take-off From Mid-runway?
Posted: Sun May 11, 2003 2:44 am
by KLAX
I bet no-one has ever seen an A340 do an intersection take off
I have, and it was deliberate
F-WWCA the A340-600 demonstrator does it often here
At
LAX sometimes ATC clears Brasilias and Saabs for take off from twy Echo, which leaves them 9000 and some feet left.
Interesting story about intersection take-offs comes from the airport where I did flight training KVNY/Van Nuys California
The runway there is 8000ft long. Our FBO was halfway down that runway at a taxiway entrance known as 13 Echo. Routinely, Cessnas and Pipers depart from that intersection to reduce taxi times and make room for the G-Vs and Lears holding at the full-length. I always thought it was stupid to take that intersection, both dangerous and risky, especially when a taxi to the left runway (4000 feet long) would keep us out of the way of any other aircraft, on our own runway.
Sure enough it happened. Infact, an Aircraft I flew numerous times was being rented, and the pilot took it out to 13E and was told to "taxi into position and hold". Unfortunatley the tower controller had forgotten he had just cleared a Cessna 182S to land on the same runway. The 182 sliced off the right wing of the Piper 140 (N15831) spilling fuel all over the concrete. Luckily both pilots came out un harmed, but its just not a smart procedure IMO.
The same thing happened when a USAir 737 hit a Metro at
LAX (24L) in the early 90s. Metro was doing an intersection departure...
-Clovis
RE: Prop Jet Take-off From Mid-runway?
Posted: Sun May 11, 2003 10:03 am
by Guest
Dear Rick -
xxx
Looks like your airline and my airline have different philosophies... you can take it personally - against me... since when I joined
AR in 1993 as their flight training manager, I insisted to forbid intersection takeoffs, it took about a year of politics, and business dinners in exclusive restaurants, to finally get the blessings and approval of the chief pilot...
xxx
Reduced power takeoffs... inherently reduce the incidence of engine failures during the critical portion of takeoffs... you and I both agree, but I differ with you for the use of intersection takeoffs... that is a remainder of my years with the PanAmigos...
xxx
We do other things to try to improve flight safety, one that I got from TWA and that I got approved as well is the V1 speed reduction when the runway required is less than runway available, after reduced power computations...
xxx
But please, agree with me about one thing, there must be a few pilots who have wished not to have taken that intersection when they arrived at the scene of the accident... at the other end of that shorter runway...
Happy contrails Rick...
(s) Skipper
RE: Prop Jet Take-off From Mid-runway?
Posted: Sun May 11, 2003 11:47 am
by Guest
Forgot to mention, Rick...
xxx
Another thing that we do down here is "improved climb" when we have excess runway to increase the climb (performance) limit weight...i.e. at Barajas... It is an approved Boeing alternate procedure...
xxx
Some people say that it is more dangerous... I personally dont think so - your opinion, and do you Gentlemen do that in UK?...
xxx
(s) Skipper
RE: Prop Jet Take-off From Mid-runway?
Posted: Sun May 11, 2003 8:18 pm
by Rick767
Skipper,
Every airline has their own policy in this regard, and that is to be respected of course. I have done very few intersection departures in my time, but those I have done are like I used in my example 1,000ft down a 10,000ft+ runway. With our policy that this means no thrust reduction such a takeoff is normally far less limiting in performance than a full-length departure (V1 will be reached much sooner).
Do bear in mind this is not typical procedure, like I say I have done this only a handful of times (mainly so that we don't miss our ATC restriction, so we need to "jump" the queue of departing aircraft at full length). This could avoid a long wait for a new slot at some times of day, not what you want with the engines running at the end of the active...
As far as reduced power take-offs go, like you my airline stresses that every bit of thrust reduction will go a long way to preserving the life of our engines. We always reduce take-off and climb thrust wherever we can, despite the increase in trip fuel burn and noise footprint that this creates.
Our calculations under JAR for reduced thrust take-off require that ASDA is greater than or equal to ASDR. (Accelerate-Stop Distance Available is greater than Accelerate-Stop Distance Required, for those not familiar with the terminology). That is assuming our ASDR is the sum of the following distances:
(1) Acceleration on all engines at the take-off thrust setting to V1
(2) Further acceleration with all engines operating for a further 2 seconds
(3) Full braking and speedbrake for the aircraft to come to a complete stop, assuming any deceleration is not initiated until the end of (2) above.
Reverse thrust does not come into the equation.
Since in reality we are not going to take 2 full seconds to initiate braking action after passing V1, and that we will in reality use full reverse thrust on all (available) engines, there is a good margin of safety built in to the calculations.
Our company also stresses that a take-off with maximum derate can be
just as limiting in runway performance as a max-weight departure.
"Improved Climb" with excess runway is not a procedure I am familiar with. What does it involve exactly? I recall discussing something like this with regard to PIA 747 departures from Manchester (using up more runway than you need to attain a higher rotate speed?).
Personally I didn't see how this helped improve the climb, perhaps you can describe the procedure better?
Happy contrails Captain
Rick.
RE: Prop Jet Take-off From Mid-runway?
Posted: Sun May 11, 2003 11:57 pm
by ScooterTrash
Several years ago, I was fortunate to do some B737 training at the UAL training center at
DEN. Then (and would imagine now as well) had a procedure called the "Improved Flaps 1 Takeoff." The purpose of this procedure was to carry more weight out of high elevation fields such as
COS.
It has been a while, but my understanding of the Improved Flaps One Takeoff is this. A lesser flap setting and greater rotation speed is used to increase the initial climb rate, in order to lift greater weight. This necessitates having a long runway, long enough that you can "re-balance the field" taking into account the higher V1. Maybe there are some more jet pilots who can shed more light on this procedure, but that is what I remember about it.
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon May 12, 2003 12:09 am
by Rick767
I think what you are referring to would simply be regarded a "Flap 5" takeoff on the 757/767... results in a higher rotate speed but a better second segment climb performance. Flap 15 (a more typical setting) gives us a lower rotate speed (so less runway used) but a poorer second segment climb.
It all depends whether the take-off is limited by runway length or climb performance.
The greater rotation speed associated with the lower flap setting is required merely to create the same amount of lift for the given weight. The initial climb angle is increased with the lower flap setting due to the reduction in drag.
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon May 12, 2003 9:29 am
by Guest
Improved climb (or sometimes named "improved performance") - example (747)
Runway limit weight 350 tonnes (flaps 20)
Climb limit weight (2nd segment) 330 tonnes (flaps 20)
Therefore we could takeoff at 330 tonnes...
xxx
However the aircraft AOM contains a graph permitting increased takeoff weight when extra runway will be available, possibly a gain of say 10 tonnes, where the increased Vr speed (and increased
V2)... for 340 tonnes or so in this case, will permit a 2nd segment at higher weight - since higher Vr and
V2 is used...
xxx
Obviously Rick, your airline does not use that procedure, however if you look in your aircraft AOM - chapter 23 or 24 for Boeings... you will see it illustrated, unless "they took that page out" - The gain is most beneficial for higher flaps setting i.e. flaps 20 takeoff, generally we use 10 flaps... in the 747.
xxx
Here we use it at airports which are at high elevation, if we are "climb limited", such as LEMD in summer...
All the best
(s) Skipper
RE: Prop Jet Take-off From Mid-runway?
Posted: Mon May 12, 2003 5:11 pm
by Rick767
Skipper,
Thanks for the description, very interesting procedure. I wonder if any US 757/767 operators use that at all (HAL?).
As you guessed they "missed that page out" on our manuals for sure. Perhaps it is not even a 757/767 approved procedure?
Cheers.