Intersection Departures

[Typhoon1244]

I believe thats what I said initially.

Well, not exactly. I asked a performance question, and you gave me a certification answer.

Don't take it too hard, though. You're a lot like Mary Schiavo: even when she has the right answer, nobody takes her seriously because she's a wacko...

 

[dispatchguy]

Learnt somthing today. Sure never thought about 121 operations making intersection departures. I'm all for flying smart, but it reminds me of what my uncle used to say about runway behind you and fuel left on the ground. Just didn't think it was done with larger planes.

Last (I can't help not mentioning this one), what's with these "engineering departments"? Y'all building runways or using them?! Must be like the "engineering department" that fixes leaky plumbing and broken light switches in hotels.

Every airline, whether a major or a very small regional, has an ops engineering department - or someone that holds that responsibility. They generate all the performance data used in flight operations. Even if you dont have a perf engineering department in house, for 121 operators, they still have someone (usually contracted) to perform the function (ref. A009 of the OpSpecs). Even if a line crew cant access them, your dispatcher can get them 24/7 to generate a legal weights table, such as when runways are shortened, or in the case of an intersection departure that tower wants.

 

[wingnutt]

Don't take it too hard, though. You're a lot like Mary Schiavo: even when she has the right answer, nobody takes her seriously because she's a wacko...

roflmao...ba-hahahahahahahahaha

 

[WrightAvia]

Hey, flychicaga...hope school is going well! We'll be tangling out there at MKE soon as you get on the line, as I fly in there alot.

Some day you'll be taxiing to 7 Right in the Saab and some old Vin Diesel looking mofo in a caravan will landing and making Alpha 4 with whimsical ease. That'll be me.

Hope to see you out there soon!

 

[NEDude]

To put it basically, for 121 operators this is airline specific.

I have been at two 121 carriers, at one airline you could not use the intersection unless you had the numbers for that particular one. At the other airline you could use any intersection provided you had the numbers for a more restrictive intersection. Both procedures were spelled out in the particular ops manuals for each airline.

 

[JECKEL]

I think an example of this is "or was" BHM. They had cranes erected on the field for construction. Certain intersection departures did not allow for for the lateral consttraints under part 25.
However, intersections FURTHER down the runway (considered more restrictive, I guess) were allowable because the cranes were no longer a lateral concern.

More restrictive was allowable while less restictive was not.

If you don't have the numbers, don't do it. There is a reason!

 

[GCD]

Having the good fortune to have worked with and learned from the man who sold the performance data computations to Jeppesen, that most of you use, the short answer is no.

Read some of the above for the reasoning. I'm too lazy today.

Gary Owen! 4/7 Cav!

 

[Typhoon1244]

They had cranes erected on the field for construction. Certain intersection departures did not allow for for the lateral consttraints under part 25. However, intersections FURTHER down the runway were allowable because the cranes were no longer a lateral concern.

This must have been an isolated incident since lateral clearances are normally computed for the entire length of the runway, not certain intersections.

For the record: Atlantic Southeast Airlines pilots are authorized to make intersection takeoffs provided they have data for a more restrictive intersection. The problem we were having a while back is that some of our guys were reasoning that if we were legal for, say, 17R at Yankee, we must also be okay to use 17C at Yankee. Not true! Even if the remaining runway distance is equal or longer, you can't substitute one runway's numbers for another. (Frankly, it never even would have occurred to me to try this!)

I wonder why this varies so much from company to company? ASA can, Skywest can't. Eastern could, Sunjet didn't.

 

[ClassG]

Both airlines where I worked, the answer was "NO" simply because you don't HAVE the data on board to prove it, so you don't do it. The same held true if that particular APD PAGE happened to be missing from the performance data. If it wasn't on the aircraft, it wasn't legal. If you knew it was missing, you had it faxed prior to dispatch. If you found it missing after pushback, you used what you had or returned to gate to get it. (At least, that's how it worked in THEORY.)

As for Skyboss - I haven't seen such a Dork around here since Mr. Concorde. You just don't get it, bro. We don't want to be you. We don't want your job. We aren't interested in how much you think pilots should be paid. And when Maglev trains take over the planet we hope they shut your airport down first.

 

[surplus1]

Typhoon

I don't doubt you for a second when you say that your carrier "approves" this procedure. With all due respect, that doesn't make it right.

Many are the airlines that have come up with internally "approved" how-to's, that subsequently were proven to be the product of erroneous thinking on the part of some program manager or flight standards guru and the rubber stamp of the FAA. We are not infallible any of us and the incidence of bogus "approved" procedures for a variety of things is more prevalent than most of us know or are willing to admit. All too often they aren't uncovered until the NTSB gets into the act. When a procedure is questionable, someone should take the time to have it changed to one that is not. You make waves in the process but it needs to be done anyway.

I still say that if you don't have the data for the specific intersection, on board the a/c, you should not accept the departure.

For your own gratification I have a suggestion. Just take another look at that avatar of your beautiful baby boy, then tell the tower "unable" and taxi to the end. The minute or two you might save just isn't worth it. Sometimes one foot of altitude, two degrees of heading, 100 #s of fuel or 5 seconds of time can make all the difference in the world.

Sincerely --- and sorry I said too much.

 

[GCD]

Surplus,

I'll put my family on your airplane with peace of mind. As for some of the other respondants to this post...

Start thinking about the consequences of doing things that are not backed by proof. In other words, if the data isn't there for that intersection, your widow can't prove you were right when the vultures come for your estate.

 

[Typhoon1244]

Surplus, for once, you've actually offended me.

I am not a cavalier pilot. I've inconvenienced more passengers than I care to think about because I lean heavily to the conservative side operationally. In this particular instance, in Dallas/Ft. Worth, I took off with, I think, 12000 feet of runway available instead of 13400. It allowed us to depart in ten minutes instead of ninety minutes. (I had already abandoned one takeoff because we couldn't get a green "config OK" message even though there was nothing wrong. Turned out to be a queertron.) If I hadn't thought it was safe, I wouldn't have done it!

Safety was never a question in my mind. Legality was.

As far as this kind of intersection departure is concerned, safety still isn't a question, particulraly in light of the research I've done after the fact.

P.M. me and I'll tell you my name so you can take your family off my plane if you ever hear it. It's your loss.

 

[GCD]

Typhoon,

I don't think Surplus or I were trying to offend you. In fact, I applaud you for being the professional to ask the question.

When I eluded to "some respondants," I was actually referring to a couple who had cavalier attitudes, not you.

I think this is a valid discussion because there are so many pilots who fall into the rush-rush get the flight out mentality.

I don't think any of us need to PM our family names to you, as I believe that you are trying to be a professional by asking questions.

I sincerely apologize if you think I was trying to insult you.

 

[surplus1]

Typhoon

Surplus, for once, you've actually offended me.

I'm very sorry. I had no intention of offending you in any way. I'm not questioning your professionalism. On the contrary, the fact that you asked the question at all clearly indicates your high regard for what you do and how you do it. That's the mark of a Pro.

Safety was never a question in my mind. Legality was.

That is exactly what I assumed. I agree that legality is the prime issue, but to a certain extent safety is also a consideration. Some things are safe and legal. Some things are safe and not legal (like this one). Other things are more safe and legal and still others are more safe but not legal. It''s a mixed bag and there is always more than one option available to the professional pilot like yourself.

In this job there are literally dozens of people, most working quietly behind the scenes, trying to take your license directly or indirectly. They include your friends in the FAA, wheather reporters, dispatchers, chief pilots, check airmen, instructors, AME's, etc., etc. I'm against helping any of them if I can avoid it.

The variety of answers you got to your question reveals its importance and the magnitude of confusion that revolves around the concept. It was a great question and I'm sure you will make the right decision when the time comes.

Again, my apoligies. I did not mean to offend. I did mean to emphasize that the hurry-up zeal that appears prevalent in some operations can be catching and we pilots often make "safe" decisions that are not legal or that could be a lot more safe and a lot more legal, if we just took our time.

I'll ride with you any day and there is no need to know your name. My views are not personal in nature. I'm just one pilot talking openly to another pilot about an issue that is pertinent and obviously in need of study.

As we speak, a member of my family happens to be riding on your airline. I have no clue as to the crews name and I'm not worried. My only concern is the drive to and from the airport.

PS. I still think its not legal.

 

[WindyCityPilot]

I'm a bit confused here... are we talking planning for an intersection departure that gives you 6000 feet, then actually departing from an intersection that gives you 7200 feet, or are we saying you planned for something like 8000 feet, then took off from an intersection that gives you 7200 feet?

Also realize your takeoff data is predicated on you holding the brakes and departing from a stop with takeoff power. Those conducting rolling takeoffs would be in essence departing "illegally" if we are going to be picky. I think the key here is to ensure that you are completely safe and operating in accordance with the FARs and your company's procedures.

 

[Eagleflip]

OK, I follow the logic that prevails in this thread.

How about this twist? How do you accomodate partial runway closures, e.g. "the first 1200 feet of runway 31L is closed?" For example, this info is routinely included in the NOTAMS or ATIS at JFK due to surface icing.

You now have to use an intersection (conviently located 1200 feet down) that you may or may not have data for. (We at JB do have that info, but my question is for illustrative purposes.)

So...do you have a way to calculate takeoff data given NOTAM/ATIS info? We have a section in our computer-based performance software where one can enter closed portions of a runway, either at the approach or departure end, so we are legal. I would think every 121 carrier has a similar process, but you may have to contact the dispatcher for their input.

If so: Given the originial question, I'd say that since you have the capability to calculate your data using full length minus the portion that leads up to the intersection, you'd be legal.

Thoughts?

 

[Typhoon1244]

...are we talking planning for an intersection departure that gives you 6000 feet, then actually departing from an intersection that gives you 7200 feet, or are we saying you planned for something like 8000 feet, then took off from an intersection that gives you 7200 feet?

We're talking about having numbers for 9000 feet of runway, and using 12000...on a runway that's 13400 long total.

I think some of you guys are wrong about the lateral clearance data. If you might be okay laterally from a certain intersection but not from a longer one, then you wouldn't be okay for the full length.

I'm going to really get into this issue...might even call the ACDO...anonymously, of course.

 

[dispatchguy]

Also realize your takeoff data is predicated on you holding the brakes and departing from a stop with takeoff power. Those conducting rolling takeoffs would be in essence departing "illegally" if we are going to be picky.

Just an FYI - in Europe (I know we're not there, but humor me) the distance required to position the airplane from the taxi way to fully aligned and ready to takeoff is considered.

I have an Airbus brochure about flight performance, and it said (I thought) that it soon will be here in the US...

 

[Typhoon1244]

A fellow pilot who's better educated (and more experienced) than I said this on a different board:

YES - you may take off from any intersection on that runway that provides MORE runway than the intersection for which you calculated the takeoff data.

The premise is that increasing your runway over and above the minimum required for the intersection takeoff further balances your field - you will have more than the minimum runway required to accelerate to V1, have an engine failure, and stop on the remaining runway. Additionally, the earlier rotation point using the longer portion of the runway gives you an added margin in the required climb gradients above obstacles in the takeoff path - remember that those are covered by meeting the weight restrictions in the runway column of the runway analysis. The weight restriction in the climb column will not be affected by using longer runway portions - that column only changes with field elevation and does not take into account obstacle clearance.

...the lateral clearances will not be affected by using more of the runway available. The only times this really becomes a factor is when there is a charted departure procedure that must be used in the event of an engine failure - Roanoke's 24 Dixxy, for example. Regardless of which runway intersection you used, you MUST follow the charted procedure in the event of an engine failure in IMC if you predicated your takeoff weight on the numbers in that runway column.

 

[SSDD]

I'm surprised by some of the responses, and the conspiracy theories. I stand by my original answer: It depends. Ask your performance people, if they say its covered in the analysis, and your management approves it, then there's no problem.

We are making too many assumptions. WindyCity, yeah, some times performance is based on standing takeoffs, but not always. Even when it is, there are provisions for rolling takeoffs, for instance at my current airline, there is a "penalties" section, and one of the lines in it states, "for rolling takeoffs subtract XXX." So if I'm more than xxx pounds under my max takeoff weight, I'm legal to do a rolling takeoff.

In general, we can talk about how our respective companies do it, but thats not the only answer, even when we fly similar equipment.