ADS-B: Safe *or* Legal
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Ignore for the moment airspace where ADS-B is required. I'd still optionally love to have it on my motorglider and shared sailplanes I fly. Especially with a little white summer haze and viewed head- or tail-on, we're basically invisible in an all-white modern glass ship. We can't hold altitudes specified by the hemispheric rules and seldom maintain a specific heading for long. I get it. Very-low power draw and light weight electronics make ADS-B installations on gliders entirely practical, except for one thing: we run from batteries and predicting how long those batteries will last is rather a crap shoot. The rules state that if you have ADS-B installed, it must be on. What happens if the battery runs dry in flight, or, in the case of a powered glider, needs to be turned off to have sufficient reserve for an engine start?

The answer I've gotten so far, from various sources (FIRC instructors, a couple random FAA guys, Soaring Society of America reps, one visit to the AOPA booth in 2019) is that if my ADS-B drops out in this manner, I'm in violation. 

True or not?

While “the always on” rule also applies to transponders, a transponder dropping out seems to cause much less of a fuss. The other extreme is a soaring buddy flying his newly ADS-B equipped Pacer into a farm field behind his hunting lodge was picked up by ATC and interpreted as a crash. They responded by calling out a full search & rescue, complicated by there being no cell phone coverage at his lodge. Gliders end up landing in strange places - will ATC call out the CAP search planes if we're ADS-B equipped? Or must we resort to flight following or as one SSA person suggested, while rapidly running out of options, scoping out a hay field, now look up the frequency for the sector and call ATC all while configuring for a no-go around and scanning for cows in the LZ?

If it proves to be the case that losing battery power risks a citation, then I'll invest in parachute instead and hope the Baron who center-punches me has also invested in parachutes. 

8 Replies
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1372 Posts

Jeffry Stetson: 
 

The answer I've gotten so far, from various sources (FIRC instructors, a couple random FAA guys, Soaring Society of America reps, one visit to the AOPA booth in 2019) is that if my ADS-B drops out in this manner, I'm in violation. 

True or not?

If you've already got the answer from the FAA ("a couple" of times, no less), who would you believe if they told you otherwise, and how much weight do you think their opinion would carry if the FAA initiated a violation enforcement action against you?

My suggestion to you is to carry some spare batteries.

 

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As Ronald said, carrying some spare batteries would solve the problem of running out of battery power. ADS-B can drop out at lower altitudes when line-of-sight between the aircraft's transmitter and ground stations is blocked by terrain. That happens a lot in the mountains of Western North Carolina where I'm based. If you don't file a flight plan or get flight following, I don't think ATC will interpret it as a crash. I used to be a CAP mission pilot and the only time they initiate search and rescue is if the Air Force Rescue Coordination Center (AFRCC) is contacted to find a missing aircraft. That can happen if you have filed a flight plan but are overdue or if you suddenly drop out of communication with ATC while receiving flight following. Even if you don't file a flight plan, if you are overdue at a destination and out of contact with someone who is expecting you, they can contact 911 and ask for search and rescue. The solution is to stay in contact by calling on a cell phone or texting when you are on the ground. If you are out of cellular coverage, then a satellite based texting option such as Garmin InReach or SPOT Messenger is a way to stay in touch. If you register your IMEI number with Flight Service, that also gives them a way to contact you before they initiate a search.

The benefits of ADS-B Out overwhelm the costs in my opinion. You get a more complete traffic picture with ADS-B Out. Every time I fly I identify traffic on TIS-B that I cannot see until I am much closer. Like any tool in aviation, you cannot rely solely on it but it significantly increases traffic awareness. If you actually do crash, having a more precise location from your ADS-B flight path dramatically shortens the time to rescue and might save your life.

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The “random FAA guys” applies in that the question was not in their field of expertise. Even so, very few even non-random FAA guys are fluent in glider rules and operations. There have been very few in my in-air experience with ATC who have not been confused by my legally-required 1202 squawk, for example.

Who would I tend to believe? An AOPA answer from someone who's who's looked into the subject with or for the FAA. But the AOPA doesn't even offer “SSA” in the profile options, so we're too small in both number and annual expenditures to attract much attention.

“Carry spare batteries” (hooked up how?) is also the solution to electrical failure in ASEL too, is it not? Yet, I've never heard anything about violation being written for loss of power in that situation and have with respect to gliders. What's the difference? One plans for outcomes that do not always happen the way one wishes. Okay to blink out in the one case but not the other? Apparently, the only certain way to avoid violation is to avoid installing the equipment in the first place.

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“If you don't file a flight plan or get flight following” was exactly the situation my friend was in when they called out the rescue people based on his ADS-B track. As far as spare batteries, see above. Carry a sat phone? ($1k plus subscription). Should not then everyone do so regardless of what they fly? 

So, carry a spare battery … what does than mean in detail? What's the FAA-approved method for doing so? STC's are rare or non-existent. Buying one to plug into the cigar lighter and leaving it floating around on the floor is hazardous in at least two ways. Without a proper mount, it's a major danger bouncing around the cabin in turbulence or in a crash. Installing a fixed mount is at least a form 337, but then immediately runs into the problem of getting a light-enough, small-enough FAA-legal battery. Will the cigar lighter take the current draw (probably) but the accessory plugs of present day likely will not. Now one is into modifying the electrical system and getting that approved.

I agree that ADS-B out is a worthwhile safety feature, but do not wish to get a violation for installing it and having my battery(s) die. There's not a good “engineering” solution. Known is that ADB-OUT does not work while doing aerobatics. The International Aerobatic Club worked out an agreement allowing it to “fail” during such operations, but AFAIK, no such accommodation was made for gliders or use in non-electrical system aircraft. 

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1372 Posts

Jeffry Stetson: 
 

“Carry spare batteries” (hooked up how?) is also the solution to electrical failure in ASEL too, is it not?

Not in any light single with which I am familiar, other than one with no electrical system when hand-held portable devices are in use.  There's no way to swap the main battery in such planes from the cockpit while flying.  I was under the impression that the original poster's glider has a rechargeable battery to power the avionics, and it is readily removable to recharge between flights – a lot different than the 20+ pound main batteries mounted in the engine compartment or tail section that ASEL's generally use.  I'm thinking the battery he uses is much smaller and lighter than a Gill G-25 or the like, and relatively easy to swap out in flight.

 

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You didn't give any details about how ADS-B Out would be installed in your glider. Obviously you can't carry around spare main batteries and swap them in the air. An ADS-B transponder uses a fair amount of battery power like any transponder. If you wanted to make sure that you have enough battery to last an entire flight, then installing a higher capacity battery might be the way to go. How about an Odyssey SBS J16? It's light but powerful at 15 amp hours.

Can you use a wind-powered generator like the Gennipod sold by Aircraft Spruce that provides 4 amps at 12 vdc and 75 mph? They are only for experimentals and ultralights but you didn't mention if your glider is experimental.