Class D airspace question.

[Huggyu2]

Class "D" airspace is determined by a simple formula. This formula is located in FAA Order 7400.2F. The dimension is determined by measuring the distance from the ARP,(Airport Reference Point), to the end of the furthest runway then dividing that distance by 6076. Then by adding 3.5, this will give you the radius for that specific airport.

Does this answer give the distance in NM or SM?

 

[BushwickBill]

Hi,

Class "D" airspace is determined by a simple formula. This formula is located in FAA Order 7400.2F. The dimension is determined by measuring the distance from the ARP,(Airport Reference Point), to the end of the furthest runway then dividing that distance by 6076. Then by adding 3.5, this will give you the radius for that specific airport. Hope this helps.

Regards

(5000/6076)+3.5=4.3229

 

[paulsalem]

Captain says I checked in inside of airspace.

I would have looked at the guy like he was crazy. Since you were IFR you've allready been cleared in.

What did he want you to just step on everyone else's calls, and mess things up even more?

You should have told him, that as the PF and the more experienced captain he should have slowed down.

 

[Flymach2]

Originally Posted by Huggyu2
Does this answer give the distance in NM or SM?

Well, it doesn't specifically indicate the unit of measurement, but I believe since the divisor of 6076 is being used it would be considered NM.

Regards

 

[puddlejumper]

You may have been inside the Class D whne you contacted the tower, or you may not have been. Generally, and I use the term loosely, the diameter is 4 miles, but there may be extensions for IFR approaches.

I'm sure the term you meant to use was radius versus diameter. I just thought I would clarify your 4 mile thing.

On a related note, I had a guy look at me like I was crazy 'cuz I pitched up over 12 degrees the other day, no pax, to keep the IAS below 200 kts. He was like, "what are you doing?" He had no idea there was a speed limit below 2500' and within 4 miles of the airport on departure. We were empty, so I guess we accelerated better than usual.

PJ

 

[RipCurl]

Thanks FlyMach2. For those interested, I dug this description up in that document.

Edit - Here's a better resource (pdf): http://[SIZE=-1FAA Order 7400.9P. It is the current description of all designated airspace and reporting points in the US.

 

[A Squared]

A little ancient history here.

Before all the airspace was reclassified to make our fellow ICAO members happy, I suppose, airspace around airports with control towers were called Control Zones with lateral dimensions of 5 statute miles(plus IAP extensions) and vertical dimension of surface to, but not including, 2500' AFL. People complained for years about the use of statute miles for distances when everbody used nautical miles for navigation. DME distances were expressed in NM instead of SM.

A little corrected ancient history:

Before the airspeace redesignation, what we now call Class D airspace was known as the "Airport Traffic Area", not a control zone (a Control Zone has become Class E airspace). While the standard ATA was a 5 SM radius, it was 3000ft AGL, not the 2500 that it is now.

Despite the history, any attempt to define a "standard" class D segment are futile. There are plenty of exceptions. For example: I keep a plane based at a tower controlled airport in which the boundaries of Class D airspace are a North-south street, an East-West street, a shoreline, a line between the mouth of a creek and a point of land, and another line between the mouth of the same creek and a highway intersection. The point being, if there are exceptions to the standard, you can't rely on a "standard" definition of Class D airspace, so discussions of "standard" dimensions are merely of academeic interest. The only relevant question is what are the boundaries of the Class D airspace at the airport in question?

I would have looked at the guy like he was crazy. Since you were IFR you've allready been cleared in.

No, strictly speaking, you haven't complied with the requirements of 91.129. Remember, he said there was no approach control, so, I'm assuming the clearence for the visual came from Center. 91.129 requires you to "establish communication with the facility providing air traffic services prior to entering that airspace" In this case "the facility providing air traffic services" would be the tower.

 

[Say Again Over]

Good information!

 

[RipCurl]

Just thought I'd add this experience:

A few days after I made the above post, I took one of my students up to the tower at our airport. Order 7400.9P says the airspace here is 4.0 nm. When I asked the tower manager how big the airspace is, he told me 4.3 nm. I asked where he got that number, and he pulled out his SOPs and showed me the document he has outlining the airspace, which is several years old. Sure enough, it said 4.3 nm. Obviously, one of these documents is wrong. I suspect the SOPs would hold up in court if it came down to it, but who knows. I'd imagine there are tons of other airports with the same circumstances.

Moral of the story: the FAA makes policy, not sense.

Also, I learned something else: our tower is responsible for runway separation, nothing more. Technically, traffic advisories and sequencing are additional services provided on an as-available basis. Of course, in practice, this seems to be their primary job. It was just a bit of an eye-opener for me.

~Mike, a perpetual student of aviation

 

[BushwickBill]

Also, I learned something else: our tower is responsible for runway separation, nothing more. Technically, traffic advisories and sequencing are additional services provided on an as-available basis. Of course, in practice, this seems to be their primary job. It was just a bit of an eye-opener for me.

~Mike, a perpetual student of aviation

That makes the trip into APC even more frightening. We are missing an approach sector in the North Bay and center just sort of turns you loose about ~ 10 -15 miles. It's a very crowded sector lots of VFR traffic some without transponders. JAL has training in the pattern and the radio calls can be well quite long. Sometimes 2 or three calls for 1 aircraft. If Tower is not being responsible for seperation then who is? I guess no one? Not a diss on the tower guys I like them all. Maybe more controllers is an answer?

Thanks for all the positive input by the way I have been following this tread for a while.