Question about airspeed in class B?

[minitour]

I stand corrected. I guess I need to update my books!

When I took my ATP written, there was a question in there about being in class B airspace and what the speed restriction was, and the answer was 250 knots. But on second thought, I think the airplane in the question was also below 10,000 feet.

After reading through the current FAR's, I agree with the last post.

I'll admit that even I thought there was a 250KIAS limitation in Class B during my PVT stuff...

Then I started getting really close to the FAR/AIM in this Instrument crap and I've been probably reading too much of to much in this....

...oh well, at least the pages aren't sticking together like some people I know...

-mini

 

[English]

FAR 91.117 states 10,000' not Class B! Lots of people incorrectly assume that since most Class B's go up to 10,000' that's the reason for the speed limit.

In places like Denver and Atlanta it is common practice to accelerate to above 250 once above 10,000 and still within the Class B.

Here's an excerpt from a legal opinion dated 10/3/1993: "On September 16, 1993, the Airspace Reclassification Final Rule became effective. Under the provisions of this rule, TCA's are reclassified as Class B airspace areas. FAR Sec. 91.117(a) now states, "unless otherwise authorized by the Administrator (or by ATC in the case of operations in Class A or Class B airspace), no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 mph)." FAR Sec. 91.117(b) now states, "unless otherwise authorized or required by ATC, no person may operate an aircraft at or below 2,500 feet above the surface within 4 nautical miles the primary airport of a Class C or Class D airport at an indicated airspeed of more than 200 knots (230 mph)." Under this regulatory scheme, it is now clear that the pilot operating in a Class B airspace area at and above 10,000 feet MSL is not subject to a 250 knot speed limitation."

So, let's make this a little more complicated (but not a lot).

Let's say you have class b airspace in Hawaii, where the 250 kts below 10,000 feet does not apply more than 12 miles offshore. So, inside the class b, from 20 miles until reaching 12 miles, below 10,000 feet, 350 knots all the way?

 

[Freight Dog]

So, let's make this a little more complicated (but not a lot).

Let's say you have class b airspace in Hawaii, where the 250 kts below 10,000 feet does not apply more than 12 miles offshore. So, inside the class b, from 20 miles until reaching 12 miles, below 10,000 feet, 350 knots all the way?

Gotta love cargo...

 

[igneousy2]

So, let's make this a little more complicated (but not a lot).

Let's say you have class b airspace in Hawaii, where the 250 kts below 10,000 feet does not apply more than 12 miles offshore. So, inside the class b, from 20 miles until reaching 12 miles, below 10,000 feet, 350 knots all the way?

I would say it's true, unfortunatelly you wouldn't get to do it very often unless you were going out of your way just to go fast. Most of the routes don't go that far offshore. You may be more than 12 miles from HNL but you aren't usually 12 miles off shore unless you are coming from directly south, but there is nothing directly south. I've heard that Hawaiian and Aloha have an exemption but I don't know that for sure. I do know that they routinely do 300knots indicated while being vectored for the 8L channel. When I'm doing 240 and the controller is telling Aloha that the traffic they are following (me) is 50 knots slower then I'm guessing they aren't following the 250 rule. Legaly or not...I don't know.



Later

 

[Vector4fun]

When I'm doing 240 and the controller is telling Aloha that the traffic they are following (me) is 50 knots slower then I'm guessing they aren't following the 250 rule.

Heck, you don't have to be in HNL to see that happen.....

 

[islandhopper]

I would say it's true, unfortunatelly you wouldn't get to do it very often unless you were going out of your way just to go fast. Most of the routes don't go that far offshore. You may be more than 12 miles from HNL but you aren't usually 12 miles off shore unless you are coming from directly south, but there is nothing directly south. I've heard that Hawaiian and Aloha have an exemption but I don't know that for sure. I do know that they routinely do 300knots indicated while being vectored for the 8L channel. When I'm doing 240 and the controller is telling Aloha that the traffic they are following (me) is 50 knots slower then I'm guessing they aren't following the 250 rule. Legaly or not...I don't know.

Later

There is no exemption. it is legal, when you're 12 miles off shore, you are in international airspace. Or outside the ADIZ, that might be it. One or the other or both. Throw your radar on next time you get the JULLE arrival and stick a 20 mile ring on it. If you do a JULLE arrival you are not 12 miles until just before coming abeam Diamond Head. If you get roped into the Koko Head arrival then your going for a drive.

On our International runs.. Straight south of Honolulu may only be the arrivals and departures for the few South Pacific runs. But don't forget we do many more arrivals into Maui from California every day. Those are straight out of the North. It is legal fly a descent profile at say 290 until 8K that works out to about 240 @ 12 miles.

On our inter-island runs.. Going into places like Kona and Lihue you can adjust your descent profile to take advantage of the rule and slow down later as you approach both airports from the deep blue.

We slow it down coming from Lihue to Honolulu as Kaena Point sticks out into our flight path and puts us in the 12 mile deal way out over the water still. Going into Maui you are over 10K while still over Lanai so we slow it down from Lanai into OGG. Coming into HNL from the East you need to slow down when the controller asks you to, or abeam Diamond Head. (12 miles) The controllers kind of expect you to keep a certain pace and if you slow at 10K way out closer to Lanai than Oahu they will often ask you to speed it up.

Remember, the airspace between HNL and OGG is traditionally the busyest, most congested run in the USA. Not any of the NE or SO Cal corridors. But PHX into So Cal was impossible some days. 250 the whole friggin way some days!

All in all I like the way things are in Hawaii. Go fast, keep it safe.

 

[English]

islandhopper,


Our ops manual has a statement restricting us to 250 knots within the class B. Not sure why, since it is not a FAR. So that's about 20 NM out of HNL.

 

[islandhopper]

islandhopper,


Our ops manual has a statement restricting us to 250 knots within the class B. Not sure why, since it is not a FAR. So that's about 20 NM out of HNL.

I dont have mine with me, does it say anything about the controllers authority?

 

[English]

Nope.

 

[Guitar Guy]

Here's the applicable FAR, 91.117 (from the FAA's own website):

§ 91.117 Aircraft speed.
(a) Unless otherwise authorized by the Administrator, no person may operate an aircraft below 10,000 feet MSL at an indicated airspeed of more than 250 knots (288 m.p.h.).

(b) Unless otherwise authorized or required by ATC, no person may operate an aircraft at or below 2,500 feet above the surface within 4 nautical miles of the primary airport of a Class C or Class D airspace area at an indicated airspeed of more than 200 knots (230 mph.). This paragraph (b) does not apply to any operations within a Class B airspace area. Such operations shall comply with paragraph (a) of this section.

(c) No person may operate an aircraft in the airspace underlying a Class B airspace area designated for an airport or in a VFR corridor designated through such a Class B airspace area, at an indicated airspeed of more than 200 knots (230 mph).

(d) If the minimum safe airspeed for any particular operation is greater than the maximum speed prescribed in this section, the aircraft may be operated at that minimum speed.


Operations in Class B airspace are specifically addressed in para. (b) which states very clearly that Class B ops are governed by para. (a) - isn't that a nice bit of misdirection. That means that in Class B and below 10,000 ft. MSL, an aircraft is restricted to 250 KIAS. In Class B but at or above 10,000 ft. MSL, there is no 250 KIAS restriction. Of course, the caveat continued in para. (d) allows for speeds over 250 KIAS in Class B when operating below 10,000 ft. MSL.

I know that this question is sometimes asked in interviews, so it's a good one to know.