RJ Wake Clearance for Piston Single

[avbug]

Mickey,

"There is no specified time in the AIM for a small aircraft (you) departing from the same threshold behind a large aircraft (CRJ). "

The AIM is not regulatory, but provides only general guidance. There is a lot of material not covered by the AIM. FAA Order 1770.65M provides, in paragraph 3-9-6 (copied below, for reference) distance separations for aircraft on the same runway.

Advisory Circular AC-90-23E advises that controllers must wait to minutes for separation between a light and heavy aircraft, unless the pilot advises otherwise. "b. For VFR departures behind heavy aircraft, air traffic controllers are required to use at least a 2 minute separation interval unless a pilot has initiated a request to deviate from the 2 minute interval and has indicated acceptance of responsibility for maneuvering his/her aircraft so as to avoid the wake turbulence hazard."

During an intersection takeoff, this time is expanded to three minutes.


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. If you can determine distances by reference to suitable landmarks, the other aircraft need only be airborne if the following minimum distance exists between aircraft:
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.

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.
b. A preceding landing aircraft is clear of the runway.

 

[Mickey]

Avbug...
I will restate it this way. The AIM nor the AC90-23E specify any time interval between small aircraft and large aircraft for takeoff separation from the same runway threshold. Why did you bring up AC90-23E. Are you trying to confuse or impress the original poster. AC90-23E reiterates what is already in the AIM(which is a good source of info in one place).
Bringing up FAA order 1770.65M still doesn't answer the poster's question. If you taxi into position and hold after my jet departs and then are cleared to take off, I,m quite sure I'll be off the runway and 6000'ft away from you unless you taxi really fast. You even added info about separation behind heavy aircraft. This is also available in the AIM without having to dig up AC90-23E. The poster didn't ask about heavy aircraft.
Remember KISS. Keep It Simple S.....
I mean no offense but hey. Some people spend way too much time going into details about things that weren't even asked on the original post way too much on this board.

 

[Snakum]

For those relatively new pilots reading this for assistance I'll add my .02 ...

I have been knocked around HEAVILY in a C152 by a departing DC-9 (not the stretch model either) and once thought I was going to die behind a B737 while in a C172 even though I had the required seperation. I don't remember the wind exactly but it must have been such that the vortext was lingering.

Moral ... if you ain't sure ... ask the controller to give you a quick turnout (on TO) or a looooooong landing. In a spam can you CAN GET INTO TROUBLE behind the smaller jets. And if ATC gets testy ... f*ck them.

Minh Thong

 

[avbug]

Mickey,

Why did I bring up other references? Why did you bring up the AIM? That was never a part of the origional poster's comments either.

"The AIM nor the AC90-23E specify any time interval between small aircraft and large aircraft for takeoff separation from the same runway threshold. "

Of course it advises a time interval; that's why I posted it. Didn't you read it? Two minutes, and three minutes if it involves an intersection takeoff.

The suggestion that because something is not in the AIM, it doesn't exist, is misleading. I introduced two other common references to show that it does in fact exist, and that other references are available which may be useful. In point of fact, with direct references to your previous comments, they are useful.

I am trying to impress nobody. The origional poster's questions have been awnsered in full, and the thread has crept somewhat. Simply because every post in a thread is not a direct address to the origional poster, don't get too excited. Life is too short.

"The poster didn't ask about heavy aircraft." The AIM reference you use refers to "larger aircraft", and for certification purposes, any aircraft over 12,500 is a large airplane. Heavy, large, whatever. The poster commented on being asked to depart behind an aircraft that was both considerably larger, and heavier. The point is simple and straight forward. The time intervals specified in the AIM and advisory circular refer to larger aircraft, and do not use "heavy" in the context of the ATC definition of "heavy." Therefore, yes, the origional poster did ask about heavy aircraft, and the question was answered nicely by a variety of different posters.

Note also that "larger" refers to an aircraft which is bigger, with no specific relative difference. Therefore, clearly this refers to the difference between the posters airplane, and the RJ in question.

AC 90-23E is not merely a reprint of what is in the AIM, as it contains more material and is specifically published to address the issue, rather than a small passing reference as found in the AIM.

Take it for whatever it's worth, and I'm certainly sorry it brings you heartache.

Incidentally, AIM 7-3-6(b)(8) advises a two minute interval behind departing or landing larger aircraft...just as it does in AC 90-23E. You'll note that it stipulates "larger" aircraft, rather than simply "heavy."

Finally, the advisory circular does not reiterate what is in the aeronautical information manual. The AIM reiterates what is in other publications; it's nothing more than a general common reference which is compiled from other Orders, Advisory Circulars, Regulations, and Handbooks.

 

[172driver]

I knew avbug would have you for dinner. Wrong guy to argue with!!

 

[XJAVRO]

The BAE146/AVRO takeoff weights are in the 90,000lbs range. The Avro produces very bad wake turbulence, much worse than DC-9, 737, 727 and so on

 

[Wefly4fun]

Going into JFK one afternoon in a B-1900 I was following an ERJ (not a CRJ) and we got rocked pretty hard. It was early afternoon so traffic was light so it was definately from the ERJ. It was not uncontrollable just a very rough ride. I've never ridden the tail of a CRJ so I'm not sure what the vortices are like on them so... You made a decision based on your past experience and you lived to fly another day!

 

[Mickey]

Avbug you really should read carefully and clearly before you quote. 7-3-6(b)8 of the AIM states that you should wait 2 minutes after a larger aircraft has executed a low approach, missed approach or touch and go landing. The two and three minute delays come from 7-3-9. Read them carefully. In regards to wake turbulence separation minima, ATC classifies aircraft as:small-41,000lbs or less mctow: large 41,000-255,000: Heavy more tahn 255,000. We are talking about wake turbulence and not certification so the 12,500lbs you mention does not come into play.

 

[Mickey]

Avbug. Read my original post again. (the you you started quoting from). Did I print any wrong information there? No.
Read your post and you will find several wrong things printed. If you are going to give people advice, make sure it is accurate before you give it out. Thats why it brought out the "heartache."

 

[AWACoff]

Mickey,
Please go easy. Avbug has provided a lot of valuable info on this board and to myself personally. He/she is only human however so if he/she makes a mistake, don't browbeat him/her so much.

In the words of a famous nutcase drug user:
"Can't we all just get along?"

 

[Mickey]

I'm sorry. AWACoff. I would have to agree with you. I guess what started it was when Avbug started his/her post off by quoting mine and then attacking it incorrectly. I don't feel that is a good way of 'giving' information.
The one thing that I know for sure is... I don't know everything.
I know what I know and I know what I don't know.
Take care.

 

[avbug]

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