Author Topic: A little turbulance?  (Read 13542 times)

Offline rekno13

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A little turbulance?
« on: December 17, 2009, 04:07:31 PM »
Comair 606 on approach to 31R at JFK



Offline rjs176cp

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Re: A little turbulance?
« Reply #1 on: December 18, 2009, 12:05:36 AM »
Someones in a bad mood.
Any expert opinions: Is six miles always a safe following distance? Could they have been feeling wake turbulence at 6 miles?

Offline NY Z Pilot

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Re: A little turbulance?
« Reply #2 on: December 18, 2009, 05:20:39 AM »
Legally all you need is 4 miles behind a 757 with a commair.

Offline tripp540

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Re: A little turbulance?
« Reply #3 on: December 18, 2009, 12:19:30 PM »
 :evil: Grouchy!

Offline glencar

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Re: A little turbulance?
« Reply #4 on: December 18, 2009, 12:55:15 PM »
Legally all you need is 4 miles behind a 757 with a commair.
No, you need 5 miles.

Offline joeyb747

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Re: A little turbulance?
« Reply #5 on: December 18, 2009, 06:57:59 PM »
...at th 27 sec mark, he says " Ah we're up here in the airplane sir, but thanks for your concern."

What? That made no sense!  :?

And yes, seperation behind a B757 is five miles, as with most heavy aircraft.

And just to split hairs here...Comair is an airline...not a manufacture. The aircraft in question is a
Canadair CRJ, built by Bombardier.  :wink:
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djmodifyd

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Re: A little turbulance?
« Reply #6 on: December 18, 2009, 07:23:08 PM »
no you need 4
large/heavy/b757 behind b757..look it up

unless its a heavy 757 (ie B753  or B752 w/added tip tanks) then its 5

djmodifyd

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Re: A little turbulance?
« Reply #7 on: December 18, 2009, 07:26:32 PM »
...at th 27 sec mark, he says " Ah we're up here in the airplane sir, but thanks for your concern."

What? That made no sense!  :?


And yes, seperation behind a B757 is five miles, as with most heavy aircraft.

And just to split hairs here...Comair is an airline...not a manufacture. The aircraft in question is a
Canadair CRJ, built by Bombardier.  :wink:

makes perfect sence
they were getting turb..saying they don't know if it's off the B757 or not, and the controller says "hes 6 ahead you have plenty of room"
pilot then says  "Ah we're up here in the airplane sir, but thanks for your concern" meaning we are feeling something so we are being careful, you are in the tower, we are in here trying to not endanger our lives

Offline joeyb747

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Re: A little turbulance?
« Reply #8 on: December 18, 2009, 07:29:44 PM »
When you say it that way it makes sense...just came off kinda snappy of behalf of the pilot...he could have just said "We are taking it easy here."
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djmodifyd

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Re: A little turbulance?
« Reply #9 on: December 18, 2009, 07:35:12 PM »
When you say it that way it makes sense...just came off kinda snappy of behalf of the pilot...he could have just said "We are taking it easy here."
yea i agree with you..but the tower controller didn't need to say what he did, that is probably what made the pilot say that
i would have just said "yea just do what you can" or something to that matter

Offline NY Z Pilot

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Re: A little turbulance?
« Reply #10 on: December 18, 2009, 07:49:20 PM »
Its def 4 miles behind a 757.

Offline joeyb747

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Re: A little turbulance?
« Reply #11 on: December 18, 2009, 07:49:46 PM »
no you need 4
large/heavy/b757 behind b757..look it up

unless its a heavy 757 (ie B753  or B752 w/added tip tanks) then its 5

When you say "b757 behind b757" are you referring to one B757 following another B757? If so, then four miles is correct. The aircraft in question in this case was a CRJ, I would classify that medium (not positive on that). If that is the case, and I'm reading the chart correctly, then the separation is five miles. This table comes form Wiki in the section on Wake Turbulence:

http://en.wikipedia.org/wiki/Wake_turbulence

(Sorry for the lousy copy job here... :wink:)

Preceding aircraft        Following aircraft                   Minimum radar separation
Super                          Super                                     4 NM
                                   Heavy                                     6 NM
                                   Medium                                   8 NM
                                   Light                                      10 NM
Heavy                         Heavy                                     4 NM
                                   Medium                                   5 NM
                                   Light                                       6 NM
Medium                      Light                                        5 NM
« Last Edit: December 18, 2009, 10:07:50 PM by joeyb747 »
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Offline joeyb747

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Re: A little turbulance?
« Reply #12 on: December 18, 2009, 08:05:42 PM »
I guess it would depend on what classification the CRJ is...

From FAA:
 
http://www.faa.gov/air_traffic/publications/atpubs/aim/Chap7/aim0703.html

"7-3-9. Air Traffic Wake Turbulence Separations

a. Because of the possible effects of wake turbulence, controllers are required to apply no less than specified minimum separation for aircraft operating behind a heavy jet and, in certain instances, behind large nonheavy aircraft (i.e., B757 aircraft).

1. Separation is applied to aircraft operating directly behind a heavy/B757 jet at the same altitude or less than 1,000 feet below:

(a) Heavy jet behind heavy jet-4 miles.

(b) Large/heavy behind B757 - 4 miles.

(c) Small behind B757 - 5 miles.

(d) Small/large aircraft behind heavy jet - 5 miles.

2. Also, separation, measured at the time the preceding aircraft is over the landing threshold, is provided to small aircraft:

(a) Small aircraft landing behind heavy jet - 6 miles.

(b) Small aircraft landing behind B757 - 5 miles.

(c) Small aircraft landing behind large aircraft- 4 miles."
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djmodifyd

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Re: A little turbulance?
« Reply #13 on: December 18, 2009, 08:34:12 PM »
no you need 4
large/heavy/b757 behind b757..look it up

unless its a heavy 757 (ie B753  or B752 w/added tip tanks) then its 5

When you say "b757 behind b757" are you referring to one B757 following another B757? If so, then four miles is correct. The aircraft in question in this case was a CRJ, I would classify that medium (not positeve on that). If that is the case, and I'm reading the chart correctly, then the seperation is five miles. This table comes form Wiki in the section on Wake Turbuence:

http://en.wikipedia.org/wiki/Wake_turbulence

(Sorry for the lousy copy job here... :wink:)

Preceding aircraft        Following aircraft                   Minimum radar separation
Super                          Super                                     4 NM
                                   Heavy                                     6 NM
                                   Medium                                   8 NM
                                   Light                                      10 NM
Heavy                         Heavy                                     4 NM
                                   Medium                                   5 NM
                                   Light                                       6 NM
Medium                      Light                                        5 NM


that might be true in ICAO standards..but not here in the good ol USA
a CRJ is considered a large..and as posted above referencing the .65.  a large behind a b757 is 4 miles.  and yes when i said a b757 behind 757 i meant following.


edit..i see thats from the AIM...but its still the same in the .65
« Last Edit: December 18, 2009, 08:37:26 PM by djmodifyd »

Offline joeyb747

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Re: A little turbulance?
« Reply #14 on: December 18, 2009, 10:05:40 PM »
Guess you learn something new everyday!  :-D I didn't know the CRJ was considered a large aircraft...I would have said medium...
Thanks for the info!
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Offline Fryy

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Re: A little turbulance?
« Reply #15 on: December 19, 2009, 12:25:06 AM »
...at th 27 sec mark, he says " Ah we're up here in the airplane sir, but thanks for your concern."

What? That made no sense!  :?


And yes, seperation behind a B757 is five miles, as with most heavy aircraft.

And just to split hairs here...Comair is an airline...not a manufacture. The aircraft in question is a
Canadair CRJ, built by Bombardier.  :wink:

makes perfect sence
they were getting turb..saying they don't know if it's off the B757 or not, and the controller says "hes 6 ahead you have plenty of room"
pilot then says  "Ah we're up here in the airplane sir, but thanks for your concern" meaning we are feeling something so we are being careful, you are in the tower, we are in here trying to not endanger our lives

Exactly, well put.
I don't think they were out of line at all. The pilots have final authority and if they were getting wake or just hitting rough air, they were still feeling something and were just taking care of themselves and the passengers. None of us were in the flight deck at the time, and neither was the controller, so the pilot(s) were just using their best judgment in regards to safety.


Offline Photle

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Re: A little turbulance?
« Reply #16 on: December 19, 2009, 08:43:30 AM »
Guess you learn something new everyday!  :-D I didn't know the CRJ was considered a large aircraft...I would have said medium...
Thanks for the info!
Well, in the FAA definitions, there is no "medium" class.
You have small (less than 12 500 lbs), Large (heavier than 12 500, but not more than 255 000) and heavy (more than 255 000)

djmodifyd

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Re: A little turbulance?
« Reply #17 on: December 19, 2009, 08:57:37 AM »
oh..i guess i could add on to this...all airplanes have a maximum turbulent air penetration speed. So no matter what is causing the rough air..pilots can only fly so fast through it.  So 180 knots (assigned by the controller) might be above that max airspeed