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Here are some of the airspaces where FAR 91.215 requires aircraft to have transponders--

(b) ...

(2) All aircraft. In all airspace within 30 nautical miles of an airport listed in appendix D, section 1 of this part from the surface upward to 10,000 feet MSL;

(3) Notwithstanding paragraph (b)(2) of this section, any aircraft which was not originally certificated with an engine-driven electrical system or which has not subsequently been certified with such a system installed, balloon or glider may conduct operations in the airspace within 30 nautical miles of an airport listed in appendix D, section 1 of this part provided such operations are conducted -

(i) Outside any Class A, Class B, or Class C airspace area; and

(ii) Below the altitude of the ceiling of a Class B or Class C airspace area designated for an airport or 10,000 feet MSL, whichever is lower;

Question 1: May an aircraft with no engine-driven electrical system and no transponder operate at 10,500' MSL in the airspace 10 miles west of South Valley Regional airport (U42) near Salt Lake City, where the overlying Class B shelf has a floor at 11,000', and a ceiling at 12,000' MSL? (Link to sectional chart.)

Note that KSLC is one of the airports listed in the Appendix referenced in FAR 91.215(b)(ii)-- this is a reference to the Mode C veil.

Question 2: May the same aircraft operate at 17,500' at the same location?

Question 3: (only applicable if the answers to (1) and (2) are both "yes")-- Does the "or below 10,000' MSL" clause of FAR 91.215(b)(3)(ii) have any actual practical significance of any kind? What is an example of some airspace where an aircraft with no engine-driven electrical system and no transponder may not operate, but would be able to operate of the "or below 10,000' MSL" clause were absent from FAR 91.215(b)(3)(ii)?

Note that FAR 91.215(b)(3) is simply an exemption to 91.215(b)(2), which appears to only apply up to 10,000' MSL, so it appears at first glance that the answers to the questions ought to be "yes", "yes", and "no". Is this really correct?

See also related question FAR 91.215-- may an aircraft with no electrical system and no transponder overfly Wheeler AAF at 9500' MSL?

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  • $\begingroup$ Aren't the jets allowed to really ratchet up their speed above 10,000? Like the 250 knot limitation goes away? I don't think the FAA/ATC wants some small plane puttering along that they don't know about and having it be run over by something fast. $\endgroup$ – CrossRoads Jun 25 at 15:37
  • $\begingroup$ That's likely why when they wrote the new regs for ADS-B-out (FAR 91.225), they wrote them a little differently in a way that WILL appear to prohibit flight at both of the locations referenced in parts 1 and 2 of this question. But it appears to me that the letter of the regulations for FAR 91.215 do not do so, and that the "or 10,000' MSL" clause is completely useless in this reg. I wonder if the FAA has ever issued an interpretation addressing this. Basically, it looks like they didn't really quite say what they meant to say, when they wrote the reg. $\endgroup$ – quiet flyer Jun 25 at 15:42
  • $\begingroup$ @StephenS -My point is that the "Below the altitude of the ceiling of a Class B or Class C airspace area designated for an airport" clause of 91.215(b)(3)(ii), in combination with the language of 91.215(b)(2), would still prohibit operation (w/ no elec system or transponder) above the NYC class B airspace at 9500' MSL, even if the "or 10,000 feet MSL, whichever is lower" phrase had not been included in 91.215(b)(3)(ii). So your example, while true, is not an example of a case where the "or 10,000 feet MSL, whichever is lower" phrase in 91.215(b)(3)(ii) is making any difference, it seems to me. $\endgroup$ – quiet flyer Jun 26 at 16:00
  • $\begingroup$ @quietflyer You're right, I read it wrong. Comment deleted. $\endgroup$ – StephenS Jun 26 at 17:58
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The answers to the questions appear to be "yes", "yes", and "no". Neither FAR 91.215(b)(2) nor FAR 91.215(b)(4) have any effect above 10,000' MSL.

The "or below 10,000' MSL" clause in 91.215(b)(3)(ii) has no effect on anything at all and does not prevent an aircraft with no electrical system from operating above Class B or Class C airspace as long as it is above 10,000' MSL.

This is clarified in this 2006 interpretation from the FAA Office of the Chief Counsel.

It possible that the original intent of FAR 91.215 was to prohibit aircraft without electrical systems and transponders from flying above 10,000 MSL above any Class B or C airspace that lies within a Mode C veil; if so the regulations were inadvertently written in a way that did not accomplish this. This has been rectified in FAR 91.225, pertaining where aircraft without electrical systems and without ADS-B-out will be able to fly starting January 1, 2020-- these aircraft will no longer be able to overfly ANY Class B or C airspace, regardless of altitude and regardless of whether or not the airspace lies in a mode C veil -- see related question What additional airspace will be off-limits to an a/c w/ no elect. system or xponder under 91.225 (ADS-B) compared to under 91.215?

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    $\begingroup$ Well, I didn't intend to self-answer, but then I found that interpretation. Looks like someone didn't write the reg to say quite what it was really intended to say. The new regs for ADS-B-out are constructed differently in a way that appears to avoid this problem and would prevent the aircraft with no engine-driven electrical system from overflying a Class B or C ceiling at ANY altitude, or from exceeding 10,000' under a Class B or C shelf. The regs will come into effect soon so we only have a few more months of hazard to endure... $\endgroup$ – quiet flyer Jun 25 at 16:15

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