Class B Clearance Questions

[SkyHog]

Ok - so I have a few questions about clearances into Class B airspace.

If I am cleared into Class B airspace, and the altitude I have chosen will put me into the Class B at one point, out at another and then back into it, do I need to get clearance each time I penetrate, or does the first clearance clear me until I exit the lateral limits of the class B airspace?

If one is going to an airport that happens to be inside the Class B to surface area, and ATC says "Remain clear of the Bravo," what to do? Land elsewhere and hope that a different controller later on will let you in, or can you plead your case?

Does ATC frown on flying over the Bravo airspace? I know they can't really control it, but is it something they'd rather not deal with? I don't want to be a pest to anyone, especially someone whose job is to separate traffic.

Just how hardcore are the altitude assignments generally? I have flown in Boston's bravo, and they were super friendly to GA, but that was a while ago and I was still like a 10 hour pilot. I believe my CFI was doing most of the flying. How many feet is an acceptable deviation before getting dinged? I know that consensus is that a pilot shouldn't drift at all, but there are times, such as looking at a chart that things can get away for a few seconds.....50 ft? 100? 300?

What happens if a clearance is cancelled after a pilot is already in the bravo airspace? Does the pilot have to leave immediately, or is this one of those things thats never really done?

 

[SCCutler]

Nick, I am trying to envision the airspace where you'd be in - out - in at one altitude (except if you are touring / sightseeing). As a practical matter, when you are cleared into the Bravo, you are also by definition being positively controlled, so you'll be squawking a discrete code and talking to the controlling authority, so if you are discussing what you're doing and where you're going, you'll be fine (except, I hear, in Chicago).

As for when you are headed to a facility within the surface B-space, you'll have already determined the airport-specific procedure for that field, and they will clear you into the B for that transition. But if they don't, for some reason, you sure ain't goin' in! Again, hard to imagine this circumstance (flat refusal to allow access to the B to use a facility in the B ).

Remember, their job is not to exclude traffic from the B-space at all cost, it is to safely administer traffic entering, transiting and exiting the B. If traffic is a problem, of course, they can certainly deny you entry to the B space for trasiting, but if you are originating or "destinating" (is that a word), you should not have a problem being granted access- that's what hey are there for- but you will do so under their control an dfollowing their procedures.

Over the B- "frowned-on"? Nope, you're not in their world, you don't matter to them.

Altitude assignments matter very much; these guys are handling complex traffic in 3d in real time.Maintain altitude and heading as assigned, or you mess up their sometimes-elaborate plan. I can tell you (fom experience) that if they decide from behavior that you cannot follow instructions well, then the routing you get may become much longer, not for punishment, but for safety.

Have never heard of a B clearance being "canceled" when you're in the space. Have definitely heard of them sending someone out.

 

[HPNPilot1200]

Nick, I am trying to envision the airspace where you'd be in - out - in at one altitude (except if you are touring / sightseeing). As a practical matter, when you are cleared into the Bravo, you are also by definition being positively controlled, so you'll be squawking a discrete code and talking to the controlling authority, so if you are discussing what you're doing and where you're going, you'll be fine (except, I hear, in Chicago).

As for when you are headed to a facility within the surface B-space, you'll have already determined the airport-specific procedure for that field, and they will clear you into the B for that transition. But if they don't, for some reason, you sure ain't goin' in! Again, hard to imagine this circumstance (flat refusal to allow access to the B to use a facility in the B ).

Remember, their job is not to exclude traffic from the B-space at all cost, it is to safely administer traffic entering, transiting and exiting the B. If traffic is a problem, of course, they can certainly deny you entry to the B space for trasiting, but if you are originating or "destinating" (is that a word), you should not have a problem being granted access- that's what hey are there for- but you will do so under their control an dfollowing their procedures.

Over the B- "frowned-on"? Nope, you're not in their world, you don't matter to them.

Altitude assignments matter very much; these guys are handling complex traffic in 3d in real time.Maintain altitude and heading as assigned, or you mess up their sometimes-elaborate plan. I can tell you (fom experience) that if they decide from behavior that you cannot follow instructions well, then the routing you get may become much longer, not for punishment, but for safety.

Have never heard of a B clearance being "canceled" when you're in the space. Have definitely heard of them sending someone out.

Great post there!

I wanted to add most facilities only see 100 foot changes of altitude. I'm assuming your using a Mode C xpndr. Mode S is more exact, but not even certain ATC can see the extremely accurate altitudes on their screen. Besides on a controllers scope your datatag reads out altitude in 100's of feet so say you're at 5,500 and your a PA28; this would be 2 sample datatags (in a terminal environment, Center tags are 3 lines):

N1234A
055*010 (altitude and speed)
(The 2nd line also alternates between the one I just showed and this
DXR*P28 (dest. and type..of course you have to tell them that info when you contact them)

I believe a Class B clearance is a class B clearance (whatdoyaknow! )

Usually when getting a Bravo clearance, controllers like to tack on "advise prior to any altitude change." so that saves their bacon. You're still cleared into the class B still if I understand your specific situation correctly.

Jason

 

[MSmith]

Just how hardcore are the altitude assignments generally? I have flown in Boston's bravo, and they were super friendly to GA, but that was a while ago and I was still like a 10 hour pilot. I believe my CFI was doing most of the flying. How many feet is an acceptable deviation before getting dinged? I know that consensus is that a pilot shouldn't drift at all, but there are times, such as looking at a chart that things can get away for a few seconds.....50 ft? 100? 300?

It depends on what's going on.

If they are routing you across an approach route for IFR traffic, especially into the "Main" B airport, they'll expect you to be pretty good (within 100 feet, better if you can). They may be routing someone only 500 feet above or below you and they are timing your crossing with others' descents.

If you're in a quiet area of the airspace (say, 90 degrees out of the approach in use to the Main airport near the edge) they probably won't even notice your deviations as long as you correct.

They also have a general idea of weather, so they're going to be a bit more lenient to a PA28 being ping-pong'ed up and down on a warm, sunny day with a scattered to broken layer above them.

 

[jesse]

I would think the controllers would expect you to be able to maintain at least 100 feet either way. There are very few days where this is not possible.

You should make an honest effort on all your flights to maintain altitude. This is of course more difficult on unfamiliar aircraft but once you get used to the feel of them it's not all that hard.

 

[Toby]

Once when I was coming back home through the Bravo over the NY area, I asked to transition, and the controller said, "Are you sure?" That threw me! I said yes, and he told me to watch out for the traffic coming down from the north toward Newark, and I was not to deviate from my altitude at all. "Not one foot higher or one foot lower," were his exact words. That was a particularly busy day, but yes, they do want you to stick to your altitude and heading.

 

[SkyHog]

Thanks for the info guys. My question about the deviation was more a question of how much deviation before the magic "I have a number for you to call" words are spoken.

I always strive to mantain altitude and heading +/- nothing. I'm just curious what the regulatory limit is.

 

[Jeff Oslick]

I was taught in my instrument training that it was far more important to maintain altitude than heading. Of course both are important, but a 10 or even 20 degree heading deviation for 30 seconds (in cruise flight) typically matters much less than a 200-300 foot altitude excursion.

Jeff

 

[jesse]

Thanks for the info guys. My question about the deviation was more a question of how much deviation before the magic "I have a number for you to call" words are spoken.

I always strive to maintain altitude and heading +/- nothing. I'm just curious what the regulatory limit is.

Not sure. But I've had them pass traffic over me without much altitude clearance at all. If you drift from your assigned altitude and the other guy drifts too. You never know how busy the controller is. He might not catch it. It would be an ugly sight.

 

[wsuffa]

If I am cleared into Class B airspace, and the altitude I have chosen will put me into the Class B at one point, out at another and then back into it, do I need to get clearance each time I penetrate, or does the first clearance clear me until I exit the lateral limits of the class B airspace?

Depends on the facility.

Assuming you remain under positive control, and the controller is clear that you wish to exit then enter again - and they don't say "now clear of the Class B airspace", you should be OK. I'd be asking "confirm cleared to enter Class B" when you re-enter if there is any doubt at all.

Example: you depart a Class B, go out, do some maneuvers, come back into the Class B. You'll need a separate clearance for reentry.

If one is going to an airport that happens to be inside the Class B to surface area, and ATC says "Remain clear of the Bravo," what to do? Land elsewhere and hope that a different controller later on will let you in, or can you plead your case?

I'd be saying "intended destination is xxx airport, how soon can I expect clearance or is there a better routing?" If clearance is still denied - and they refuse to answer the questions, I'd be landing somewhere and having a talk with the ATC supervisor. Note that the major airports may delay indefinitely clearance for VFR aircraft to their airports. If you're landing at a satellite, it shouldn't be a problem (Chicago excepted).

Does ATC frown on flying over the Bravo airspace? I know they can't really control it, but is it something they'd rather not deal with? I don't want to be a pest to anyone, especially someone whose job is to separate traffic.

Yes, most - not all - ATC facilities frown on overflight. If you're on flight-following, many will reroute you around. The solution, then, is to request cancellation of flight following services early enough that they won't hold onto you and send you around. This is a problem even IFR. Dallas won't let you go over the Class B as IFR if you're below the flight levels. Same with Cincinnati, St. Louis, and Memphis. Houston requires you to be at 16,000 or above. That's IFR.

If you're not on flight following (or assigned an ATC vector), go right ahead over. If you're on flight following, you might ask the controller whether they have any issues with you going over the Bravo. Then act accordingly.

Just how hardcore are the altitude assignments generally? I have flown in Boston's bravo, and they were super friendly to GA, but that was a while ago and I was still like a 10 hour pilot. I believe my CFI was doing most of the flying. How many feet is an acceptable deviation before getting dinged? I know that consensus is that a pilot shouldn't drift at all, but there are times, such as looking at a chart that things can get away for a few seconds.....50 ft? 100? 300?

Depends on traffic. Generally, ATC can't see less than 100' deviation. I like to stay as close as I can, within 20-30 feet.

What happens if a clearance is cancelled after a pilot is already in the bravo airspace? Does the pilot have to leave immediately, or is this one of those things thats never really done?

I can't recall hearing of a clearance being cancelled once you're in. If it is, you'll generally be directed to leave the airspace immediately.

 

[Dave Siciliano]

Nick:

Everyone has added very positive remarks. Of course, there are variances. I've gotten routed through class B in many cases below the flight levels: Dallas, San Diego, St. Louis, Atlanta. It depends on traffic, workload and how you sound to them. I've had controllers tell me, and seen first hand, times when professional sounding pilots got clearances others have not. OTOH, there have been times when everyone has trouble with clearances. In general, plan on going around or over Class B if below 15,000 and you'll be safe. If you get a clearance through, that's great.

As far as VFR over Class B, just keep in mind how much traffic is coming in and out when you are flying over. You may technically be able to do this, but it may not be smart: it's Class B for a reason. Pilots have told me they've had plane after plane pass near when flying VFR over class B. Each area has approach and departure corridors, if you know where those are, you might be able to avid them. If you don't, you could be flying right into the busiest portions of the air space with no one able to warn you of a possible problem.

Kinna like MOAs, you can fly through VFR, but much faster, more maneuverable traffic may be busting through there.

Best,

Dave

 

[Everskyward]

I think most of your questions have been answered but I'd like to add:

Does ATC frown on flying over the Bravo airspace? I know they can't really control it, but is it something they'd rather not deal with? I don't want to be a pest to anyone, especially someone whose job is to separate traffic.

It's perfectly legal to fly over Bravo airspace, and directly overhead the airport is probably pretty safe. However, remember that it's going to be pretty busy to the sides above the Class B as airplanes (airlines and others) fly the departures and arrivals. They'll be traveling a high rate of speed too.

I know that consensus is that a pilot shouldn't drift at all, but there are times, such as looking at a chart that things can get away for a few seconds.....50 ft? 100? 300?

If your altitude deviation causes you to lose separation with another aircraft the magic altitude is 300 feet, I believe, at least for IFR airplanes. If there are no airplanes around the controller will probably forgive you.

 

[Pilawt]

I am trying to envision the airspace where you'd be in - out - in at one altitude (except if you are touring / sightseeing).

It can happen. In Washington State, a straight-line route from Olympia to Bellingham between 8,000 and 10,000 will bust corners of Seattle's Class B twice, 50 NM apart. That's a busy corridor, with near-8,000' mountains close to the west and a prohibited area below, so it is a concern in this area.

-- Pilawt

 

[gismo]

Altitude wise, the "legal limit" is +/- 300 ft AFaIK, but remember that there is some error in your encoder plus that 100 ft quantization which means you could hit the 300 ft limit when you were only 100 ft off on your altimeter. If your altitude doesn't vary more than 100 ft ATC will be happy and they can't tell if you do any better than that, given any instructions to maintain within 1ft or not. Of course if you are VFR in VMC, you ought to be able to see any potential conflicts unless you're being overtaken from the rear.

IME once you've been cleared into Class B, your clearance is valid until you are told otherwise or stop talking to the TRACON regardless of how many times you enter or leave. You could face the same problem vertically if you were given a clearance to enter but held at the altitude of the floor in your vicinity (BTDT). Everytime you descended 20 ft and came back up you wouldn't expect to need a new clearance would you? If you are told "radar service terminated", exit or remain clear of Class B, or handed off to a control tower outside the class B (VFR) you need a new clearance to enter but not otherwise AFaIK.

As far as landing at an airport where the class B goes to ground (fairly rare IME), you shouldn't be denied entry. It might be delayed ("remain outside... I'll get back to you") but they should eventually let you in to land.

And AFaIK the ATC bible prohibits controllers from cancelling your clearance while inside Class B. They might instruct you to exit, but they can't cancel till you comply. That doesn't mean it can't happen, but if it does, just come back with the fact that you believe you are still inside Class B.

 

[Ed Guthrie]

Altitude wise, the "legal limit" is +/- 300 ft AFaIK, but remember that there is some error in your encoder plus that 100 ft quantization which means you could hit the 300 ft limit when you were only 100 ft off on your altimeter.

I don't know that I've ever seen a maximum altitude physical deviation limit published. I believe the reason you vaguely remember +/- 300' is becuase that number is the encoder to altimeter error limit (i.e. "stop altitude squawk).

 

[Skip Miller]

Nick others have answered this nicely but I would like to add the following:

Ok - so I have a few questions about clearances into Class B airspace.

If I am cleared into Class B airspace, and the altitude I have chosen will put me into the Class B at one point, out at another and then back into it, do I need to get clearance each time I penetrate, or does the first clearance clear me until I exit the lateral limits of the class B airspace?

Listen for the magic words: Now clear of the Class B airspace, contact BigCity Departure, 120.xx." You are now out and need permission to get back in. If the controller knows your route will bring you back in, he may not terminate you as above, workload permitting. But I would always ask the controller in this case... you don't want to be busting Bravo space!

If one is going to an airport that happens to be inside the Class B to surface area, and ATC says "Remain clear of the Bravo," what to do? Land elsewhere and hope that a different controller later on will let you in, or can you plead your case?

If it is busy pleading your case won't work. Most likely a secondary airport within the B surface area will have special arrival/departure corridors and perhaps you are not lined up/proper altitude to access them, and they cannot for whatever reason vector you to the right approach. Call FSS and ask, or land somewhere else and ask what the procedure is. If you are in position for the preferred routing into the smaller airport within B space, you will get the clearance. Possible exception: your destination airport is closed due to an emergency in progress.

Does ATC frown on flying over the Bravo airspace? I know they can't really control it, but is it something they'd rather not deal with? I don't want to be a pest to anyone, especially someone whose job is to separate traffic.

Others have said that ATC frowns on this. I have found just the opposite. I have been over the NYC Bravo several times and it seems like NY Approach wants to be talking to you if you are that close to the B. And I have never been given long vectors out of my way while flying VFR over the top of the B space. Yes, I have gotten vectors for traffic and who wouldn't want them????

What happens if a clearance is cancelled after a pilot is already in the bravo airspace? Does the pilot have to leave immediately, or is this one of those things thats never really done?

They cannot cancel your clearance to enter B space if you are already in. What would be the point? Violate you for being there legally? What they can do is vector you out of the B space if they 1) need to, 2) see you flying so poorly you are a danger to the other traffic, or 3) are having a bad hair day. Chicago has that reputation.

-Skip

 

[poadeleted20]

If you're headed my way, keep in mind that the top of the ADIZ is the base of the Class A (18,000 MSL) -- which is way above the top of the B-space (10,000). So you can't fly over the BaltoWash B-space with the same impunity as going over all the others.

 

[HPNPilot1200]

Well I figured I'd hop into PhotoShop and Imageready when I came home for fun...finally decided on making this. Note: Most real life radar targets are updated on a 4 second rate the one in this is example is 2. Note that this guy must be climbing awefully fast to go 300 feet in 6 seconds AND maintaining 100 knots

The "A" means that the controller using the "A" tag owns you (yes..not only radar wise, he OWNS you )

I explained the other info earlier. I can also show you a tag from a Center's scope later tonight.

Also--some facilities (and controllers usually using Arts Color Display (ACD) or Standard Terminal Automation Replacement System (STARS)) have different colors. N90 (NY TRACON) for example ONLY has the FULL datablock on the aircraft he owns and both the target and datatag are white. Other aircraft owned by other controller are only visible when the controller hits a key to display a/c from that controller and those are shown in green. Clicking or "slewing" a target when the button is pressed down (to see him) enables the controller to release the button, but have a full datablock and target in green.

It only gets more complicated when you actually have to control em'


It's just an example...http://www.pilotsofamerica.com/forum/attachment.php?attachmentid=2988&stc=1

 

[SCCutler]

It can happen. In Washington State, a straight-line route from Olympia to Bellingham between 8,000 and 10,000 will bust corners of Seattle's Class B twice, 50 NM apart. That's a busy corridor, with near-8,000' mountains close to the west and a prohibited area below, so it is a concern in this area.

-- Pilawt

See, there, and that's why I never say, "never." Sure enough, someone will show me the exception to my experience, especially since my experience is rich with exceptions.

Now I gotta pull up a chart and take a look at that.

Thanks. Great discussion, all.

 

[gismo]

I don't know that I've ever seen a maximum altitude physical deviation limit published. I believe the reason you vaguely remember +/- 300' is becuase that number is the encoder to altimeter error limit (i.e. "stop altitude squawk).

You may be right, but I know I've heard and or read more than once that an altitude deviation in excess of 300 ft can cause a "deal" for ATC and a phone number to call for the pilot.

 

[AirBaker]

I'm guessing that most 'small' airports aren't inside of Bravo, but underneath some layer. Several class D airports are that way here in the Bay Area.

While everyone should strive to nail those headings and altitudes, I think the controllers look for how predictable you are. If you have that altitude down solid, they'll be able to squeek that TurboProp in just above you. Flounder around too much and they'll vector you way out of your way.