Visual Separation between departures
11-16-2008, 05:58 PM
#1
Gets Weekends Off
Thread Starter
Joined APC: Mar 2006
Position: Austin Tower
Posts: 175
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
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
11-16-2008, 06:16 PM
#3
Gets Weekends Off
Joined APC: Jun 2008
Posts: 107
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.).
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.).
11-16-2008, 06:21 PM
#4
Gets Weekends Off
Joined APC: Nov 2005
Position: 757 Capt
Posts: 2,419
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
Doesn't matter what he wants, airplane isn't turning invisible and the bug smashers still going to be practicing See and Avoid
11-16-2008, 06:39 PM
#5
Organizational Learning
Joined APC: Nov 2005
Position: Directly behind the combiner
Posts: 4,948
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.
.
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.
.
11-16-2008, 06:49 PM
#6
Gets Weekends Off
Joined APC: Apr 2006
Position: A300/310 Capt
Posts: 1,642
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.
In my previous military career, we used to takeoff in heavies, with 12 second spacing. That part of my life is over.
11-16-2008, 06:49 PM
#7
Organizational Learning
Joined APC: Nov 2005
Position: Directly behind the combiner
Posts: 4,948
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?
#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.
.
11-16-2008, 06:50 PM
#8
Gets Weekends Off
Joined APC: Apr 2007
Position: B777
Posts: 564
Not trying to defend the guy, but a Devil's advocate view and strictly hypothetically speaking (never happened to me 
)
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.
)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.
Last edited by FlybyKnite; 11-16-2008 at 06:55 PM.
11-16-2008, 06:54 PM
#10
Gets Weekends Off
Joined APC: Dec 2007
Posts: 829
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.
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.
