Visual Separation between departures
 

(Also posted in Hangar Talk.)

We had an interesting situation tonight which resulted in more debate and discussion in the Tower Cab. Here's what happened:

Local Controller rolls a B727 runway heading climbing to 5,000, then rolls an MD11 or DC10 right behind the B727 doing the same thing. The B727's route of flight would continue south, and the MD11 would eventually turn west when radar and communications contact was made with the Departure Controller.

The Local Controller asked the Heavy if he still had the B727 in sight in an effort to apply Visual Separation, and the Heavy driver responded with "I refuse to accept or provide visual separation" (paraphrased).

The Local Controller then had to coordinate with the Departure Controller for an early turn to the west, and some gnashing of teeth and cursing followed. The Supervisor then called the airline and asked for the Chief Pilot to call the Tower Cab. Supervisor tells the Chief Pilot that "our" expectations were for the pilot to tell the Tower if he/she was unable or unwilling to accept or provide Visual Separation between successive departures, and that Visual Separation was a tool that ATC uses to expedite traffic. Chief Pilot concurred, and said that this information would be disseminated.

So...

1. How do you feel about ATC asking YOU to provide Visual Separation between yourself and the preceding departing aircraft?

2. Would it matter if ATC did this every once in a while to get themselves or you out of a bind?

3. What are your thoughts on ATC issuing Visual Separation to each and every aircraft in the departure push as a method to expedite the flow of traffic?

4. Any other thoughts or comments about Visual Separation between successive departures?

Thanks,

MEM_ATC

I think the heavy driver was/is a prick.

Yeah, sounds like heavy just needed to respond to the Local's question by simply saying, "Yes, but we're unable."

It's the first refusal of this type that I've ever heard.

Call your colleagues in LAS about answers to your 4 questions, as visual separation is common practice there. They clear guys for takeoff while the preceeding departure is still on his takeoff roll.

I think flight crews are very willing to help his friendly ATCer get out of a potential bind. Just listen to the responses you get when you query a flight about his speed or climb/descent rates.

"...Mach .79, whaddya need?"

"2000 fpm, whaddya need?"

They don't seem to realize that you're asking out of curiosity and not necessarily because you "need' anything (apologies for the slight thread creep.).

Should have told him he's unable to engage the klingon cloaking device below Class A airspace,
Doesn't matter what he wants, airplane isn't turning invisible and the bug smashers still going to be practicing See and Avoid

During takeoff roll, I've got more important things to watch than an airplane that I'll probably be overtaking. Especially with the newer takeoff profiles we're using (early acceleration), I would be disinclined to accept responsibility for spacing unless the conditions were optimal. How fast was the 727 climbing? What was the visibility? How heavy/light am I, and do I expect to have trouble seeing him with my pitch attitude and climb rate?


I can't say that the above paraphrased response from the heavy driver was the most diplomatic, but I can't fault him for declining to accept a clearance based on him being able to maintain visual separation.




I wonder who could have been operating 727s and DC-10s. :)







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I agree with Tony. If I am taking off after a 727-200 maxed out, and am in a light A-300, I am out climbing him and cannot see him with my pitch angle. There is too much going on during t/o roll, rotation and climb out to keep another acft of unknown performance in sight. I understand that you are attempting to help the company out with decreased departure spacing, but at this point in my career, I don't feel that it is my problem, and neither should you.

In my previous military career, we used to takeoff in heavies, with 12 second spacing. That part of my life is over.

Upon further review, it appears I didn't really answer your battery of questions. I think my previous post answers #1.

#2. If I'm on the ground waiting for takeoff clearance, I'm not in a bind. What bind would you be in?

#3. I think my answer to #1 addresses this -- I would be reluctant to accept such a clearance in anything less than ideal circumstances. Excellent visibility, preceding traffic is climbing quickly, and my anticipated climb rate will be such that I won't have to struggle to look over the nose of my airplane to keep him in sight.

#4. Other thoughts? Yes. What happens when I roll down the runway, lift off, raise the landing gear, and then report that I've lost sight of the preceding traffic? Does that put you in a bind? That's the situation I think I'd like to avoid.

IF you're going to use the visual separation trick, I'd prefer the preceding traffic be assigned a heading that diverges from runway heading. That helps me see him, and gives me more of a warm fuzzy that I won't overrun him if I do lose sight.








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Not trying to defend the guy, but a Devil's advocate view and strictly hypothetically speaking (never happened to me :rolleyes:)

ATC: got the preceding traffic in sight?
Heavy: Roger
ATC: Maintain separation, turn left/right heading 000 to intercept J99, maintain 10,000, contact departure on 123.54
Heavy PilotNotFlying starts twisting heading and altitude bugs and radio knobs and then begins the readback as PilotFlying calls for "Slats Retract, After Takeoff Checklist", and adds "What was the heading again?" And then you ask yourself, where's that traffic??

Let's see the original intent was to 'drain the swamp', right?

Usually, most days/nights it isn't a problem; but, every so often caution (and events) overrides reasonable expectations. Then again some guys just enjoy being the exception to every rule.

edit........

Both aircraft are going the same way, both aircraft are cleaning up about the same altitude and accelerating at a somewhat similar rate, and both aircraft are accelerating to the same ultimate airspeed - 250 knots. Other than different climb rates that could prevent the trailing aircraft from seeing the preceeding aircraft over the nose (then you either see him or don't - it isn't about "refusing'), what is the issue?

Compare it to accepting visual sep on approach. In that case, both aircraft configure completely randomly and fly speeds that may or may not be the same. In addition, the crew is working to configure at the appropriate speeds without getting to slow for the current config (leaving few maneuvering options available to the trailing aircraft to maintain sep), they are working to align with the runway while maintaining terrain clearance, they are working to avoid wake turb issues, and they are running the Before Landing checklist.

Barring aircraft malfunction or weather (neither seem to have been mentioned), take-off is a much more benign environment relatively speaking and I see no issues with the aircrew agreeing to stay visual if it results in decreased spacing, decreased ground delays, and increased fuel savings.

O'hare approach: United xx, do you have the field in sight?

United xx: I do not, but my first officer does.

O'hare approach: United xx, your first officer is cleared the visual. :D

Vmcl for a heavyweight MD-11 could result in overtake speeds upwards of 40 knots. In other words, it's not a given that they'll both be 250KIAS.







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Well, all I can say is there are plenty of anal-retentive aviators at our airline. My personal motto is to try and un-complicate things and if I can help you out in the tower by watching a Boeing blast off to the South, while we are heading West I am happy to help. I hope I speak for the majority, but these days I don't know.

I used to fly in and out of DFW before they had a boatload of runways. This was also when AA, DL, Eagle, and ASA made DFW one of the world's busiest airports. Our airline would land 17R with an AA or two holding short to cross downfield. No long after landing and when we felt it was appropriate, we'd tell the tower - "XX 412's at taxi speed". They would then give crossing clearance to the jets holding downfield, granted 4,000 feet or so ahead of us, but by the time we told them "taxi-speed", we were below 80kts. In our opinion it helped the tower, and that would come back to us one day and it usually did.

Perhaps a better time to notify the crew of your expectations would be prior to getting them airborne, when you need immediate compliance and response. If this is a frequent expectation of ATC, put it on ATIS like LAHSO, so they can let you know if they'll be unable.

Diplomatic refusal or not, ATC gave them the option of saying no and painted themselves into a corner when that's the answer they got.

I'm all for exercising options that allow us to expedite departures when it makes sense. There are pilots out there who refuse to accept visual approaches by "following traffic" because they don't want the shift in responsibility re: wake turb & separation off ATC and on to them. They'll probably be the minority that will stiff you on this kind of departure request. Therefore, you need to make plans for dealing with the 1% factor.

Whew!!! An overtake upwards of 40kts? So, let's figure this out...

Aircraft # 1 takes off, gets say a minimum 2mile headstart, then you takeoff behind him and are climbing out at 170kts while he's accelerating to 250. So, now let's say he gains another mile. That makes his lead 3miles in front of you. But, you accelerate to 290, and with your 40kt overtake will catch up to him in 4.5 minutes. That will take you another 22 miles to catch up to him.

Bottom line...You're going to have to travel over 30 miles, and say 8-9 minutes(+/-) just to have any possibility of a collision. Doesn't seem real scary to me.

Having said all that...I think it might depend on if I'm trying to catch a D/H home on the other end.

Then why the requirement/request to maintain visual contact at all? Big sky little airplane, right? :rolleyes:

How about this?
 

I agree with the guys who don't think it's wise to accept responsibility to maintain visual separation if there is a chance that you can't see and avoid.

How about this? Instead of both aircraft using the same heading for departure, give them different headings. First aircraft-runway heading, second aircraft-runway heading plus 30 degrees, third aircraft-runway heading plus 60 degrees, fourth aircraft-runway heading....

Being able to turn at 400' (700' MSL in MEM) and fly a different heading than the guy in front of you would allow at least one guy in the cockpit to see the traffic for longer.

Yeah, like golf...trees are 90% air. Just go for it.

Seriously, though...Without the visual/request option in VMC. I believe ATC would be required to radar separate us, as if we didn't have a window to look through, or like the WX was at mins. But, it is a request. And, if Tony isn't comfortable with it, that's his call. The rest of us can just sit there and whine a few more minutes in the Conga line.

The amount of headstart would be another factor to consider in accepting a visual clearance. The original post stated, "rolls an MD11 or DC10 right behind the B727 doing the same thing." I've witnessed the clearance being given with what appears to me to be much less than 2 miles headstart, and the assumption here is, initially anyway, and certainly until achieving radar contact, the same heading. With the MD-11 using NADP2 (accelerating and cleaning up at 1,000' AGL), the closure is nothing to scoff at.

I don't like sitting in line any more than the next guy, but I really hate the paperwork involved with reporting a TA. ;) A few seconds is a tiny sacrifice for safety.







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Sounds like that's exactly what happened: The Capt was unable or unwilling to accept or provide visual separation, and he told the tower. This seems in line with "your" expectations above, so why was the Chief Pilot involved? What was the plan if the Capt said, "No, I don't have him in sight."?

I'm with Tony... I don't see where an aircraft on the ground waiting for normal separation constitutes a "bind" that ATC needs the next pilot to fix.

I may be wrong here...But, it seems that the tower controller tells you to maintain visual contact with the departing A/C in front of you, when he gives you your "reduced separation" T/O clearance. By accepting the T/O clearance, they're expecting you to at least make an attempt of continuing that visual contact/separation. If you don't want to do that, then don't accept the T/O clearance.

Isn't that what the problem was here? He accepted the reduced separation for takeoff...But, then surprised them with the refusal, once airborne.

Yes and they're out there saving commercial aviation every day one departure at a time. That said, I do respect the right of the crews to refuse such separation although the manner in which it was done likely needs work as many of us need better table manners. I will say that outside of RW 27, MEM rarely asks us if we have the preceding traffic insight when they put us into position, so it may not be surprising that a subsequent separation situation resulted in some saltiness. Other airports that do this regularly seem to be far more routine about asking if the preceding traffic is in sight, giving ample time for the safety award winners to refuse the visual separation.

...................

Why is this thread even in place? Upon executing an IFR clearance you are ATC's responsibility from T/O roll until landing........ period. in terms of separation , (unless the Capt accepts otherwise, vis-a-vie a visual approach). So how is MEM Tower mixing the two? A SID is a SID even if it's radar vectors. :rolleyes::mad::cool:

I have never in my life read ONE report of an overtake/collision on take-off in the civilian airline world.

Just read some of the ridiculous safety reports if you want a glimpse into the world of the anal-retentive here. I am not saying that an AR pilot here is unsafe, I am saying that of the many AR pilots we have, they would be least likely to comply with a request from ATC to maintain visual on departure.

Yeah but think about all the environmemtal impact studies which will have to be completed then! lol

It has also been said that there are plenty of cowboys at our airline.


I'll gladly be counted in the former group. ;)





But, we're not really talking about labels here, as labels aren't terribly useful to the discussion. We're talking about a procedure, and its relative merits and shortcomings. In some circumstances, it is a safe and useful procedure. In some circumstances, it is less safe. Given the choice of something that saves a few seconds versus something that is safer, I'll always opt for the safer route, even if it means you'll give me a dirty look. I've endured worse.







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Delivery is everything, and the delivery of "unable" by the Heavy was a little hard -- but he certainly made his point.

I found it interesting that the Tower Supervisor conveyed his expectation that the pilot should notify ATC prior to the issuance of Visual Separation -- that he would/could not accept Visual Separation.

There have been several instances in my career where I've been informed by a pilot that he was refusing to accept Visual Separation, and I've had to move on to Plan B. These were generally not a problem, as long as had not painted myself into a corner.

Personally, I believe issuing the Visual Separation before takeoff clearance is preferable -- at least this would give the crew the opportunity to say "unable" and allow ATC to switch to Plan B before the aircraft gets airborne.

MEM_ATC

Tony,

This has always been my impression -- that pilots were supposed to fly the airplane, and controllers were supposed to separate the aircraft. The longer I watch things change within the FAA, it seems as if these roles are getting mixed together.

There have been previous discussions on this forum about Visual Separation with regards to Visual Approaches, and many of the comments were the same -- you guys want to fly the aircraft, and you want ATC to separate you from any surrounding aircraft.

Well... I wonder too! :-)

Take care,

MEM_ATC

Well here in Pinehurst/Southern Pines the trees really are 90% air - well, maybe at least 75%. ;)

I agree with the spirit of the request to maintain visual seperation, but I support the Capt's right to refuse. This particular Capt just scores low in the Style Category. :D

If I launch a B727 in front of an MD11 or any other type of jet that I believe will accelerate quickly -- I will always use a little extra room to avoid an overtake situation.

It has been my experience at MEM, that the B727's do not climb or accelerate very well on departure, and that the Airbuses and MD10/11's generally have very good climb-rates. With that said, it would seem to me that maintaining Visual Separation with the B727 from the cockpit of an Airbus or MD10/11 might be difficult due to the climb angle.

If something happens downstairs in the TRACON and both aircraft level at 5,000 on the Tower assigned runway heading because they can't talk to a radar Controller -- I predict a major overtake situation, and someone's gonna take evasive action at some point.

MEM_ATC

Same rules that let them tell you maintain 170kts to the FAF on a visual approach? :rolleyes:

Tony,

Some airlines get a little concerned when their aircraft start to pile-up along the taxiway awaiting a takeoff clearance. Phone calls get made... FAA Management gets involved... and then the Supervisors start telling Controllers to "tighten-up the departures" -- meaning: use some visual separation and get things moving.

There's no real bind unless the Controller is hitting a gap, but many of the new guys have taken this practice to heart and they are using Visual Separation as a means to expedite the flow of departure traffic -- and the technique is used at every opportunity.

Yes, but I try to anticipate that and switch to Plan B, which might mean that 1) I provide the Visual Separation, 2) assign you a new altitude to maintain, or 3) coordinate with the TRACON for a new heading.

One of our Rookies found himself in this predicament a while back, and the Supervisor had to coach him through the process to resolve the situation.

I agree. Unfortunately, our Informal Noise Abatement procedures have been made mandatory by the FAA, and this prevents us from turning jets off certain runways unless certain other conditions exist.

Thanks for your comments.

MEM_ATC

On that Noise Abatement note.... since we started NADP 2 departures a few months back (cleaning up at 1000 ft), has there been an increase in noise complaints?

And my two cents, the guy in question didn't have to be so rude about it. We do appreciate ATC trying to help get us out of there. It just isn't always possibly to comply with the requests, even in day light. And I certainly don't call traffic at night coming into the sort! But I can usually pick out the runway.

A SAC twenty ship MITO!! "That's what I'm TALKING about!!"

At my previous employer, PHX tower would clear you into position & hold followed by a question about maintaining visial seperation with the departing a/c.

Here is the time and place to find out. Crew responds yes, now as a crew I know that I may need to alter my normal climb profile to maintain sight of the previous departure. Not that big of a deal if I am aware of what is expected of me ...

On the other hand, crew says NO. Controller doesn't get in a bind but leaves them on the runway for a minute or two ...

Wasn't a big deal either way ...

Was the question asked of the heavy well in advance of him beginning the roll ?

caution: thread drift
 

Also having flashbacks! #18 in a 23 ship MITO outa' KI one winter. By the time we took the runway the takeoff temp was way hotter than planned.:)

In DCA, you get this type of clearance all of the time.

Since I did formation takeoffs in the military, this isn't such a big deal for me. None of my Capts have had a problem accepting it.

Usually when they give us the clearance, we have an RJ in front of us. We accelerate and climb faster than they do. We usually get turned early before they do and they then end up behind us.

-Fatty

FAA Order 7110.65, Chapter 3

3-9-6. SAME RUNWAY SEPARATION

Separate a departing aircraft from a preceding departing or arriving aircraft using the same runway by ensuring that it does not begin takeoff roll until:

a. The other aircraft has departed and crossed the runway end or turned to avert any conflict. (See FIG 3-9-1.) If you can determine distances by reference to suitable landmarks, the other aircraft needs only be airborne if the following minimum distance exists between aircraft: (See FIG 3-9-2.)

1. When only Category I aircraft are involved- 3,000 feet.

2. When a Category I aircraft is preceded by a Category II aircraft- 3,000 feet.

3. When either the succeeding or both are Category II aircraft- 4,500 feet.

4. When either is a Category III aircraft- 6,000 feet.

5. When the succeeding aircraft is a helicopter, visual separation may be applied in lieu of using distance minima.

FIG 3-9-1
Same Runway Separation
[View 1]
http://www.faa.gov/airports_airtraff...0309_Auto8.gif

FIG 3-9-2
Same Runway Separation
[View 2]
http://www.faa.gov/airports_airtraff...0309_Auto7.gif

NOTE-
Aircraft same runway separation (SRS) categories are specified in Appendices A, B, and C and based upon the following definitions:

CATEGORY I- small aircraft weighing 12,500 lbs. or less, with a single propeller driven engine, and all helicopters.

CATEGORY II- small aircraft weighing 12,500 lbs. or less, with propeller driven twin-engines.

CATEGORY III- all other aircraft.

You are scaring me Fatty...breaking out the 7110.65.

Next thing you know we will start doing approach TERPS criteria reviews.:eek:

Beertini