Alan Perlman

Permission needed if flying vertically up into Class E airspace?

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Asking for...a friend...this one is a doozy :)

(Refer to Figure 20, area 1.) You're hired to inspect a group of structures that are under construction 9 statute miles (SM) south of Norfolk International airport. What's the highest you're allowed to fly without needing to ask for additional FAA permission?

A) 470 ft. MSL
B) 853 ft. AGL - this is what we have marked as the right answer, but I'm now questioning it
C) 1,200 ft. MSL


The tower in question is 453 ft. AGL.

While the Part 107 regulations state a maximum altitude of 400 ft. AGL, you’re allowed to fly higher than that as long as you’re within 400 ft. of a tower / obstruction. You’re even allowed to fly up to 400 ft. over the topmost part of that tower.


In this case, the height of the structures under construction 9 statute miles (SM) south of Norfolk Intl airport is 453 ft. AGL. If you’re flying “as high as allowed under Part 107,” you’d be flying 453 ft. AGL + 400 ft., or 853 ft. AGL.

So the question then becomes, If you're flying a drone at 853 ft. AGL, what airspace would you be in, and would you need authorization from the FAA to operate there?

At first glance, the structures sit in Class G airspace at the surface, and Class C airspace from 1,200 ft. MSL to 4,000 ft. MSL. But THEN, someone just pointed this out to me, if you zoom out, it looks like the whole area is actually enveloped in the thick, fuzzy magenta line indicating Class E airspace starting at 700 ft. AGL.


So that means, and here's where it gets fun:

  • From the surface to 700 ft. AGL, it's Class G airspace
  • From 700 ft. AGL to 1,200 ft. MSL, it's Class E airspace
  • From 1200 ft. MSL to 4,000 ft. MSL, it's Class C airspace

OK, if this is all true, then at 853 ft. AGL, that would be Class E airspace.

So here's where I...I mean my friend. Right, my friend. Where he is stumped :)

When you look at the full 624 pages of Part 107 regulations and comments, it says :


Operations in Class B, C, D and E airspace are allowed with the required ATC permission. 

That's on page 11 in Table 1: Summary of the Major Provisions of part 107.

Then, later in the document, one of the section headers on page 329 says:



a. Operations in Class B, C, D, and lateral boundaries of the surface area of Class E airspace designated for an airport


Sounds similar, but this time it says "lateral boundaries of the surface area of Class E airspace."

On page 330, we see the same language:


The NPRM proposed to require prior permission from Air Traffic Control (ATC) to operate in Class B, C, or D airspace, or within the lateral boundaries of the surface area of Class E airspace designated for an airport.

Does this mean that if we're flying vertically up into Class E airspace, like we'd hypothetically be doing at 853 ft. AGL in this question, that we would need authorization to be there?

If so, then I need to re-write this question.

Waddya think?

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Yes,  you would need an airspace waiver or authorization for that portion of the flight that extended into class E airspace.  In that case, the portion above 700' AGL.

The regs reference class E with regard to airports because that is where class E to the surface generally exists.  Since generally flight is restricted to 400' AGL,  the regs don't mention class E that starts at 700' AGL.  But make no mistake it is still class E and permission is required.

Although you can fly higher if within 400' of a tall structure,  the FAA always defaults to the more restrictive regulation if there is overlap.

Very good question!

Edited by Dave Pitman
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3 minutes ago, Dave Pitman said:

the FAA always defaults to the more restrictive regulation if there is overlap.

That's a great way of thinking about it.

Thanks for your response, Dave!

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I don't think you do need permission.  For one there is no option for it under the ATC COA portal, there is only SFC-E.  You can't even request like Class E to 700 or 1200. If you ctrl-F Class E in the 107 "big document,"  all the references are just for boundaries of surface areas of Class E at airports. 

My thought is that they would have explicitly stated just simply Class E and not E to the surface.  I think the rationale is that E to surface at an airport would expect a higher volume of IFR traffic coming into altitudes that would put the remote aircraft closer to traffic.  IFR traffic is flying the "line."   All IFR traffic flies IAW with altitudes that provide obstacle clearance which usually allows for 500 feet of clearance over an obstacle.  E-SFC would make sense that you could have an approach without any obstacles but allow the pilot to descend down to the final altitude prior to runway visual decent point.  We call this the "dive and drive technique," to descend early to the min altitude to the approach plate.  The idea here is that you break out of the clouds sooner, level and proceed to the runway visually when doing a non precision approach.

Being that airways and routes have prescribed altitudes that ensure clearance of obstacles.  I think the reasoning why they did not state this is because of the existing rules provide a margin safety.  We can only go above 400 feet within 400 feet of a structure.  That gives a 100 foot buffer for both IFR and VFR traffic with the exception of helicopters which can get closer to things.  We are supposed to maintain line of sight of the aircraft at all times unless wavered.  This limits how far you can theoretically go with say a DJI Phantom sized aircraft.  At some point it would not be very visible.  We are to gave way to any manned aircraft.  Even in Class G if we cannot meet the other criteria, its not a free for all to take it to extreme high altitudes.

Now that's not to say they may not throw that restriction in on a altitude waiver, since now you would be going into controlled airspace where you could argue there is a reasonable expectation of IFR traffic at E-700 or 1200 near the boundaries of an airport or airway. Now you could be outside the limits of an obstacle where a plane could be at those altitudes causing conflict.  I think for normal operations since you can't even request it, it implies in my mind that it is allowed as long as you are compliant with the other criteria you can go into it.

Now I get that there maybe overlapping regs.  I don't think would be in conflict with the 107.  All the discussion in the big document is the FAA responding to equipment requirements in these various airspace and why having a waiver mitigates it.  There are equipment requirements in E.  Is the only controlled airspace where VFR pilots can enter without having to talk to an ATC facility.  Being that is the case I think we can infer that the FAA's clear intent is E to Surface.  


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The regs do only specifically mention the surface class E.


§107.41   Operation in certain airspace.

No person may operate a small unmanned aircraft in Class B, Class C, or Class D airspace or within the lateral boundaries of the surface area of Class E airspace designated for an airport unless that person has prior authorization from Air Traffic Control (ATC).

But, trying to guess the "intent" with regard to FAA regs is that.. just a guess.  Unfortunately there is not an easy answer to be found for every question.

Ultimately a judge decides the gray areas when or if an enforcement action comes to them.  Until that happens,  we all just have to guess... I guess. :)

Edited by Dave Pitman
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This is straight out of the Remote Pilot Study Guide.

"In most cases, a remote pilot will not need ATC authorization to operate in Class E airspace." 


The primary airport(s) within the TRSA become(s) Class D airspace. The remaining portion of the TRSA overlies other controlled airspace, which is normally Class E airspace beginning at 700 or 1,200 feet and established to transition to/ from the en route/terminal environment. TRSAs are depicted on VFR sectional charts and terminal area charts with a solid black line and altitudes for each segment. The Class D portion is charted with a blue segmented line. Participation in TRSA services is voluntary; however, pilots operating under VFR are encouraged to contact the radar approach control and take advantage of TRSA service.

Granted this is not law.  But it is a record of the federal government as an official training document.  Being that in 624 pages the only discussion is on E to Surface in the official 107 signed document.  That is reason to infer the FAA's thought process.  So they would be hard pressed on record for violating someone for anything that has conflicting guidance.  Also an attorney could argue because no mention was ever given for anything other than E to the Surface, that the FAA would have been complicit in their true intent.   Regulations are very specific, they can't be erroneous in their application.  Its one of the protections we have to prevent people making up rules at the lower bureaucratic level. In all reality they most likely would not violate you unless you did something else unsafe, else you would be fine.  Like I said before, you are not off the hook if you do something that considered careless or reckless.  If you do go 400 feet above the tower and have an incursion with an aircraft, you would still answer for that.

Here is the thing in my 22 years of flying the big thing we are harped on by any check airman is "where does it explicitly say that?"  Many people like to make hip pocket determinations and turn techniques into procedures.  It becomes a slippery slope when this happens because it makes the determinations of actual procedures more difficult.  This is why you have to have a valid reason you can defend yourself.  If some FAA official tried to solely violate you on being in E and you had no rationale or understanding on why you did what you did.  You will probably not be able to make a good argument in your defense.  

At the end of the day they have to go by written procedure.  If that procedure is erroneous, the ball is in their court to fix.  Realistically the FAA can't regulate every possible situation.  It is humanly impossible.  So what they have to do is put robust enough regulations out which provide for a level of safety but are not unnecessarily over burdensome.  At the same time it is up to individual pilots to use their individual judgement if what they are doing is unsafe and to discontinue.  In all practicality it makes sense.  They would get flooded with hundreds of requests for every single tower inspection that would go into E.  It just would not be practical.  This is the one time I think in dealing with sUAS ops the FAA used some rational thought.  

In the question above (A) is obviously wrong.  It is above 400 feet of the structure and at the floor of Norfolk's Class C.  (C) is not correct because you can go above 453 AGL.  If we were concerned (E at 700) 699 feet would be our max altitude.  I think with their training guidance,  (B) is the right answer.

On another note, when I did my FAAST test for the Part 61 method to get a RPIC, I believe actually had this same question and chose B, I got 100% after end of course exam. 

Edited by Shaun135
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DJI and AirMap need to watch this.  It probably explains why GEO has it wrong so much of the time..



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