Departure Separation rule of thumb

ebykowsky

ebykowsky

Cleared for Takeoff
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How much time do you give yourself to get on the runway and get air born in front of a landing aircraft? Assume both you and the landing traffic are 172's. Plane was coming in on final last night at 1.5nm out, on final. I took off in front and was turning base by the time he touched down... what's your general rule on when to go vs when to wait?
 
I don't have a hard distance rule, just a visual picture based on experience. If it's going to be close I'll coordinate with the arriving aircraft before taking the runway, because a conflict perceived by the pilot of the landing aircraft is, by regulation, my fault.
 
there was an airplane 1.5 miles out on final and you took off and were on base when it landed? BASE?

thats a slow airplane on final . . . as in 10mph maybe. Sure you did not mean cross wind?
 
comanchepilot said:
there was an airplane 1.5 miles out on final and you took off and were on base when it landed? BASE?

thats a slow airplane on final . . . as in 10mph maybe. Sure you did not mean cross wind?
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Or maybe it was a lot more than 1.5 miles out. Perception is not always reality.
 
When landing plane is turning base, or midbase, I would take off, if I have pilot's ok to do so. There's some training activity at my home airport and I don't want to make some student nervous just by announcing departure and taking runway when he/she's on base.
 
At the class c airport I fly out of ATC will give you, " cleared for takeoff without delay," any time a plane is about 1 mile away. If it works for them it works for me.
 
comanchepilot said:
then that changes the decision point, ne pas?
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That's n'est-ce pas.

facts matter Ron .. . .
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Yes, they do, but so does the perception, and unfortunately, the perception isn't always the reality. If you put three pilots at the end of the runway (or three pilots in the plane looking at the end of the runway), you'll probably get four different estimates of the aircraft's distance from the runway. It takes experience to be able to look at a plane, recognize its type/speed, and then decide based on what you're flying and how close to the runway you are whether or not you have enough time to get in the air and be out of that other pilot's way without scaring the other pilot into going around because of what you did. Radio helps, but at the end of the day, it's mostly about perception, because if the other pilot perceives a conflict, you're the one in the wrong.
 
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Always confer with pilot on final,let them know your intentions,usually make a rolling take off . Try to cause as little discomfort as possible.
 
Sorry yeah, crosswind. I was going to take off on 35 for logistical reasons when he called 5 out. I taxied to 17 when I asked for position, he called 1.5 and I stated intentions.
 
I generally ask if there is radio contact and they are close enough for me to see them. If they are far enough out I cannot see them, then I announce...
 
frfly172 said:
Always confer with pilot on final,let them know your intentions,usually make a rolling take off . Try to cause as little discomfort as possible.
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what if they don't have a radio? Can we bring our own light gun
 
ebykowsky said:
Sorry yeah, crosswind. I was going to take off on 35 for logistical reasons when he called 5 out. I taxied to 17 when I asked for position, he called 1.5 and I stated intentions.
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thats better! Hey as long as you did not get called names and he did not have to go around its cool. A Skyhawk on a 70knot short final takes 70 seconds to reach the threshold - it takes a Skyhawk less than 30 seconds to be 50 feet up - its cool.
 
Typically the guy on final should roger up something like "you are cleared for the option, this is ATC" and then you are good to go. Other than that, I'd hold indefinitely.
 
35 AoA said:
Typically the guy on final should roger up something like "you are cleared for the option, this is ATC" and then you are good to go. Other than that, I'd hold indefinitely.
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Psssh... I only answer to people who claim to be Michael Huerta.
 
Will we get to close if he has to go around?

If yes I wait, if no I go.

Relative performance of the planes involved is important as well, if I'm faster than the landing traffic I don't need to give as much room and when slower need to give extra space.
 
Reminds me of something I witnessed a few months ago....

On the jumpseat on an unnamed airline at MDW. We are #2 for departure. #1 is a bizjet (Falcon or similar). A 737 crosses the threshold to land, and the tower immediately comes up to tell #1: "Line up and wait, traffic 2 mile left base a 737". Sure enough there is southwest, on base, wing already starting to dip. Myself and the crew I'm riding with share a mutual "This will be interesting" moment. The base traffic rolls wings level for a moment to build a few more seconds of separation in. The landing traffic clears and the falcon is cleared to go. He's off just in time for the second 73 to cross the numbers.

Ref speed on a 737 somewhere between 140-160 knots, add a bit more for the maneuvering part. 2 mile base.. it can be done.
 
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