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Formation - ADS-B Out - CFR 91.225 Compliance

Chkaharyer99

Chkaharyer99

Well Known Member
Friend
My question is regarding the use of an ADS-B out equipped aircraft while flying formation in a position other than lead.

During the pre-mission brief those pilots participating in formation flights in positions other than lead are typically directed to "Choke the Parrot" or otherwise put your transponder in standby mode.[/U] The lead squawks.

For those in the flight with ABS-B out, the direction to Choke the Parrot appears to conflict with regulations outlined in:

Title 14: Aeronautics and Space
PART 91?GENERAL OPERATING AND FLIGHT RULES
Subpart C?Equipment, Instrument, and Certificate Requirements

Specifically,

CFR 91.225 (F) states, "Each person operating an aircraft equipped with ADS-B Out must operate this equipment in the transmit mode at all times."

CFR 91.225 provides the following exceptions:

"(g) Requests for ATC authorized deviations from the requirements of this section must be made to the ATC facility having jurisdiction over the concerned airspace within the time periods specified as follows:"

"(1) For operation of an aircraft with an inoperative ADS-B Out, to the airport of ultimate destination, including any intermediate stops, or to proceed to a place where suitable repairs can be made or both, the request may be made at any time."

"(2) For operation of an aircraft that is not equipped with ADS-B Out, the request must be made at least 1 hour before the proposed operation."


Lets assume these formation flights are occurring mostly in Class E adjacent to Class C and Class D.

Can someone explain why only the lead squawks/transmits and the rest standby.

What is your experience during formation flights, are participants in the flight, who are equipped with ADS-B out transponders setting them to: standby, off, on (transmit) or something else?

Your direction and experience is appreciated.

Any ATC folks out there? Please chime in.
 
My experience so far is that ATC will ask lead to have wing go standby. ATC get a audible alarm when aircraft are in close proximity. I don't think many ATC are even equipped to receive ADS-B so they don't care, they just hate to hear that alarm.
I can see where this would be against the FAR when we do that on our own but we do it anyway.
 
I know that this year's Oshkosh Airventure NOTAM had language to the effect that all Mode A/C equipped aircraft without ADS-B "out" were to squawk "standby" during the Ripon/Fisk VFR arrival procedure. That's been standard practice for years. It drives the ATC surveillance system nuts to have that many airplanes so close together at the same time in flight. However, the same NOTAM said ADS-B "out" equipped aircraft were to keep squawking in "full on" mode during the arrival procdure. I am sure some legal weenie at the FAA realized the language of the regulation would be violated if the NOTAM were to instruct ADS-B aircraft to squawk "standby" or "off". So to keep everybody legal OSH ATC had to put up with nuisance alarms for at least the ADS-B equipped aircraft arrivals. Whomever wrote the ADS-B regulations completely ignored NORDO non-electrical aircraft and situations like OSH when they added the requirement to have the system "on" at all times despite what airspace class was being operated in. It simply states if an aircraft is ADS-B "out" equipped it must be on at all times when in the air no matter what or where. That's very different than the current Mode C rule that allows "standby" or "off" in Class G etc...

Jim
 
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FAR's also require any aircraft equipped with Mode C capability to operate it at all times ( I don't remember any permission to turn it of when in Class G), but we turn that off when operating within a "flight"

When operating as a flight of more than one aircraft, the flight is considered a single entity so lead squawking meets the requirement.

I guess were it could get complicated is if an element (other than lead) in the flight has ADS-B out capability but lead does not.
 
I arrived at Oshkosh as #3 in a flight of 4. I have ADSB OUT so lead had me squawk and he went standby. I have a UAT so in other cases I've left ADSB on and set just the xpndr to standby. I can't imagine anyone getting busted if you do something reasonable.
 
It's a technical issue. When in formation everyone's transponder gets 'pinged' by ATC radar at virtually the same time, so the replies overlap and become undecipherable to ATC. In contrast, ADSB-out transmits more or less at random, so one formation member should not interfere with another.
 
rvbuilder2002 said:
FAR's also require any aircraft equipped with Mode C capability to operate it at all times ( I don't remember any permission to turn it of when in Class G), but we turn that off when operating within a "flight"
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Okay. Here is the pertinent excerpt from FAR PART 91, SECTION 215:

"(b) All airspace. Unless otherwise authorized or directed by ATC, no person may operate an aircraft in the airspace described in paragraphs (b)(1) through (b)(5) of this section, unless that aircraft is equipped with an operable coded radar beacon transponder having either Mode 3/A 4096 code capability, replying to Mode 3/A interrogations with the code specified by ATC, or a Mode S capability, replying to Mode 3/A interrogations with the code specified by ATC and intermode and Mode S interrogations in accordance with the applicable provisions specified in TSO C-112, and that aircraft is equipped with automatic pressure altitude reporting equipment having a Mode C capability that automatically replies to Mode C interrogations by transmitting pressure altitude information in 100-foot increments. This requirement applies --

(1) All aircraft. In Class A, Class B, and Class C airspace areas;

(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; and

(4) All aircraft in all airspace above the ceiling and within the lateral boundaries of a Class B or Class C airspace area designated for an airport upward to 10,000 feet MSL; and

(5) All aircraft except 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 -- --

(i) In all airspace of the 48 contiguous states and the District of Columbia at and above 10,000 feet MSL, excluding the airspace at and below 2,500 feet above the surface; and

(ii) In the airspace from the surface to 10,000 feet MSL within a 10-nautical-mile radius of any airport listed in appendix D, section 2 of this part, excluding the airspace below 1,200 feet outside of the lateral boundaries of the surface area of the airspace designated for that airport.

(c) Transponder-on operation. While in the airspace as specified in paragraph (b) of this section or in all controlled airspace, each person operating an aircraft equipped with an operable ATC transponder maintained in accordance with ?91.413 of this part shall operate the transponder, including Mode C equipment if installed, and shall reply on the appropriate code or as assigned by ATC"

The non-regulatory AIM Section 4-1-20 makes a blurb about leaving it on as a good idea but not that it has to be on. That's the same AIM that discourages straight ins at uncontrolled fields that all the Lear and Cirrus guys like to do.

I am not trying to be a wise guy. I really do want to know the correct answer. In the FARs I don't see where the current Mode C rule requires all aircraft equipped with transponders to be in operation at all times in all airspace. I operate a non-electrical aircraft out of a Class C airport and take along a ground-charged battery that is just enough juice to power a KY97 and our KT76A and encoder. When Departure cuts me loose I turn off the battery and don't turn it back on until I am returning and want to call Approach. If I am breaking a regulation I certainly want to know.

Jim
 
This spring, I departed Delta Airspace and crossed Charlie Airspace with a Charlie Squawk Code assigned by ground. I was squawking and both wing aircraft were on STANDBY. ATC requested that WING turn their transponders OFF. Appears the ADS-B Mode S out aircraft squawking STANDBY was still visible to ATC.

As others had said, all aircraft in a fight are considered one aircraft so one squawk is all that is required. Those that fly formation regularly may need to start briefing Mode S ADS-B out transponders OFF and not on STANDBY.
 
RV6_flyer said:
This spring, I departed Delta Airspace and crossed Charlie Airspace with a Charlie Squawk Code assigned by ground. I was squawking and both wing aircraft were on STANDBY. ATC requested that WING turn their transponders OFF. Appears the ADS-B Mode S out aircraft squawking STANDBY was still visible to ATC.

As others had said, all aircraft in a fight are considered one aircraft so one squawk is all that is required. Those that fly formation regularly may need to start briefing Mode S ADS-B out transponders OFF and not on STANDBY.
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Gary,

I thought that might be the case. Recently I was #2 in a two ship with my ADS-B transponder switched to standby as directed in the brief. Following the flight I checked Flightradar24 to see if there was a ground track for the practice flight and there was a complete track of the entire flight. I was perplexed by this thinking I was not transmitting, but apparently I was, even on standby.

I thought switching the transponder off might be more appropriate then there's the issue of compliance.

"all aircraft in a fight are considered one aircraft so one squawk is all that is required".

Copy, thank you!
 
rvbuilder2002 said:
I guess were it could get complicated is if an element (other than lead) in the flight has ADS-B out capability but lead does not.
Click to expand...
Actually, i've flown in that situation, but it was Mode-C carried by someone other than lead. Our lead aircraft either had his transponder in for service, or didn't have one (forget which now), so #2 ran their Mode-C instead, and made any changes ATC directed them to.
 
There are times that as "wing" I squawk since I have ADS-b and Lead did not. He left his on stand-by.
This allowed us to see other traffic.
 
MarkW said:
There are times that as "wing" I squawk since I have ADS-b and Lead did not. He left his on stand-by.
This allowed us to see other traffic.
Click to expand...

Looking for traffic on screen or out the window:rolleyes:
 
MarkW said:
There are times that as "wing" I squawk since I have ADS-b and Lead did not. He left his on stand-by.
This allowed us to see other traffic.
Click to expand...

This makes sense. As wing, your ADS-B out transponder would wake up ground stations and give traffic alerts for aircraft within range of your hockey puck. Anyone else in the flight with ADS-B in capability with the capacity to get audio alerts would hear when traffic was a factor for the flight. In the event lead had ADS-B traffic capability, they may be in a better position to see and avoid any conflicts with other traffic.

This concept seems to still satisfy this statement:

"all aircraft in a fight are considered one aircraft so one squawk is all that is required"

Breakaways, extended trail... are still one aircraft.
 
How about navigating around/under a class B but still within the 30 mile mode C veil as a formation??

Still have everyone but the lead "choke the chicken"??
 
MIKE JG said:
How about navigating around/under a class B but still within the 30 mile mode C veil as a formation??

Still have everyone but the lead "choke the chicken"??
Click to expand...
Why doesn't lead get to choke their chicken? Seems safer, as lead, really. :D
 
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