Disagreement with FAA Re: Airport Distance

[davoud]

The FAA's B4UFly App shows that I live in a no-fly zone within a five-mile radius of BWI; about 4.5 miles. This measurement is incorrect.

Using the FAA's own published coordinates for BWI from AirNav: KBWI - Baltimore/Washington International Thurgood Marshall Airport and my own precision measurements of the geographic coordinates of my house, compiled over a number of years with various GPS devices for purposes of astronomical observing, WolframAlpha.com and Google Earth Pro agree that I am 6.8 statute miles (5.9 nm) from BWI.

Using my own conservative measurements of the distance from the nearest point on BWI's perimeter to my home, WolframAlpha.com and Google Earth Pro agree that I am 6.6 statute miles (5.7 nm) from BWI.

I'm going with my measurements.

 

[N017RW]

The FAA's B4UFly App shows that I live in a no-fly zone within a five-mile radius of BWI; about 4.5 miles. This measurement is incorrect.

Using the FAA's own published coordinates for BWI from AirNav: KBWI - Baltimore/Washington International Thurgood Marshall Airport and my own precision measurements of the geographic coordinates of my house, compiled over a number of years with various GPS devices for purposes of astronomical observing, WolframAlpha.com and Google Earth Pro agree that I am 6.8 statute miles (5.9 nm) from BWI.

Using my own conservative measurements of the distance from the nearest point on BWI's perimeter to my home, WolframAlpha.com and Google Earth Pro agree that I am 6.6 statute miles (5.7 nm) from BWI.

I'm going with my measurements.

Cool. But aren't you curious about the source of discrepancy?

 

[Loudon MacReady]

@davoud. Your problem is assuming that 5nm is the criteria. The BWI Class B Airspace extends upward from the surface out to a radius of 7 nm around the airport except for a little wedge to the southwest.
Learning how to read an aeronautical chart might be a good idea for some rainy day.


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[davoud]

@davoud. Your problem is assuming that 5nm is the criteria. The BWI Class B Airspace extends upward from the surface out to a radius of 7 nm around the airport except for a little wedge to the southwest.
Learning how to read an aeronautical chart might be a good idea for some rainy day.
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Well, it has been a while, but I had 7-½ years experience reading aeronautical charts during my tour in the USAF. If I made an error it was in accepting the FAA's written word that the BWI radius is 5 nautical miles.

 

[Loudon MacReady]

What written word are you talking about? The sectional chart and Terminal Area Chart clearly show the radius.

Your link to Airnav even includes a handy snip of it!

Again, your assumption that B4UFly is just a 5-mile-circle-generator is the problem.

Well, one of the problems.


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[Loudon MacReady]

While I'm at it, you might also note, depending where exactly you live, you may be in the DC Special Flight Rules Area, which, while not a no-fly for hobbyists, does have specific requirements set forth in a NOTAM.


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[davoud]

While I'm at it, you might also note, depending where exactly you live, you may be in the DC Special Flight Rules Area, which, while not a no-fly for hobbyists, does have specific requirements set forth in a NOTAM.
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I have read the NOTAM and the FAA notification on the reduction of the DCSFRA from 30nm to 15nm. I am not in the DCSFRA. Thanks for bringing that to my attention, though.

 

[davoud]

Cool. But aren't you curious about the source of discrepancy?

In part, the unreliability of the iOS app. Gave variable results, then quit functioning after four uses (two iPhone 6's, two iPad Pros, two iPad Retinas). This while other GPS and compass apps work just fine.

 

[davoud]

What written word are you talking about? The sectional chart and Terminal Area Chart clearly show the radius.
Your link to Airnav even includes a handy snip of it!
Again, your assumption that B4UFly is just a 5-mile-circle-generator is the problem.
Well, one of the problems.
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I appreciate your efforts to educate me, but smugness does not go over well with me. Suggest you click my avatar and "Ignore." I'm waaay too dumb for the likes of you.

 

[Loudon MacReady]

Your understanding of the SFRA and FRZ is also not correct. Also clearly indicated on charts.


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[Loudon MacReady]

Ok then, have fun with the FAA.


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