Mid-Air at Winter Haven

Daleandee said:
I love ya Ron but I gotta toss a flag on this one. Your buddy needs to get his ADSB repaired as it's not functioning correctly (if the helicopters are transmitting).

First - ADSB transmits to ATC & other aircraft. I've experienced this as I've sat at the hold short line and watched my friends fly the pattern all the way to landing and I can see their speed & altitude on my ADSB display while also looking at them out the window.
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Thanks much. Now to mention it, I've seen my own complete trails doing touch-and-goes at this airport. The person who said they didn't pick up the copters isn't a semi-luddite like myself; she flies a very well-equipped airplane. She said she was picking up other planes, but not the helicopters.

I live just west of the traffic pattern, with a good view of both the airport and the downwind leg (which is always on the west side of the field). I gotta get myself the receiver to see the real-time ADS-B data on my iPad, then sit out on the deck with a frosty beverage and a pair of binoculars. Not to narc out the helicopters (if they are turning off their ADS-B outs) but just out of curiosity

Here's a photo showing the layout....taken from my bedroom window.
field.JPG

Daleandee said:
Second - Anyone flying at 400' and looking at the ADSB display needs to learn NOT to do that. At 400' in the airport environment I'm eyes outside and on final approach (or departing straight out & eyes outside).
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To be clear, *she* was flying her plane at the normal 1000-foot pattern altitude. The helicopters fly inside the fixed-wing pattern at 400 feet.

Half Fast said:
In fact, they could have politely mentioned that they were enhancing safety by going NORDO while training at your airport and thereby scaring people. After all, a very wise pilot once wrote:
:D
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I gotta quit leaving those petards scattered about. :)

Ron Wanttaja
 
Ed Haywood said:
Hate to say it, but JB is at real legal risk here.
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Maybe. I don’t think they did anything illegal. Whether there was negligence remains to be seen, and even if so it may have been solely on the part of the pilots, and that could be divided between the Cub and the Warrior.

I’m sure there will be lawsuits. Polk State has reason to believe that their training program will suffer.
 
Daleandee said:
First - ADSB transmits to ATC & other aircraft. I've experienced this as I've sat at the hold short line and watched my friends fly the pattern all the way to landing and I can see their speed & altitude on my ADSB display while also looking at them out the window.
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I admittedly don't know the technology that well. But since it needs a transponder to operate, does it need to be "tickled" by ground radar in order to transmit the ADS-B out data?

I fly out of Auburn Municipal (S50), south of Seattle. Many of the ADS tracks don't start until the plane is a few hundred feet up, and cut off when the airplane descends below a given altitude.

I realize this is also tied in to the airspeed, but this is the plot of a Twin Beech...it ain't flying that slow. The track doesn't start until it reaches 300 feet, and cuts off when it descends below 300 feet. It's still a half-mile from the runway when it cuts off on descent (landing north).
twin beech.JPG
The weird thing is, SOME of the aircraft tracks show this gap, but not all. Even my own Fly Baby maintains contact all the way through touch-and-goes, but shows this altitude cutoff sometimes. Understand that there are two different types of ADS-B...the good kind, and the cheap kind like I have.

Again, the primary radar in this area is at ~400 MSL, and the field is at 59 feet.

Ron Wanttaja
 
I'm not the one to ask about ADSB as I only know what I've read, been told, and experienced. But as I understand it the system broadcast at regular intervals as said here:

ADS-B system determines the position of the aircraft using GPS. The transmitter broadcasts that position, heading and speed at regular intervals. Transmitted packets also include the aircraft’s identity, altitude, speed and other data. ADS-B ground stations receive the broadcast data and relay the information to air traffic control centers for precise tracking of the aircraft.
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The interval is:

ADS-B data is transmitted every half-second on a 1090MHz, digital data link.
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I have no idea if it's the same for 978 UAT used below 10K.

https://www.adsbhub.org/docs/

Not sure how Flight Aware receives their information but ADSB exchange has this quote:

ADSB exchange operates a bit differently from other flight tracking sites. As a group of aviation enthusiasts, our primary goal is to answer the question of “what’s up there” rather than “is grandma’s flight on-time”.
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https://www.adsbexchange.com/faq/

Dunno if this helps ...
 
wanttaja said:
But since it needs a transponder to operate, does it need to be "tickled" by ground radar in order to transmit the ADS-B out data?
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No. ADSB provides position accuracy beyond ground based radar capabilities and was the primary reason for its development. But it does require ground based receiver facilities. Basically the ADSB OUT signals are received at those ground facilities and sent to ATC in real time which provides the NAS control/management.

For example, the hardest part of the 2nd real world test of ADSB in the GOM was finding the "ground based" locations for the these facilities. The oil companies stepped up and provided areas free of charge on their oil platforms for these ADSB "ground" stations which are considered some of the most expensive real estate in the world. The change over the previous GOM IFR ops brought by ADSB was staggering for the industry.
 
Bell206 said:
No. ADSB provides position accuracy beyond ground based radar capabilities and was the primary reason for its development. But it does require ground based receiver facilities. Basically the ADSB OUT signals are received at those ground facilities and sent to ATC in real time which provides the NAS control/management.
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Thanks. Any guesses as to why the data for S50 is getting lost when airplanes get low? No ground-based receivers in line of sight? The airport is in a ~3 mile wide valley.

Or am I just looking at a FlightAware glitch?

Ron Wanttaja
 
wanttaja said:
No ground-based receivers in line of sight?
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I believe line of sight to ground stations is still an issue but have no personal experience or knowledge of how that may affect the ADSB xmit signal. I would imagine there are other resources to find out this info. Maybe email here: ads-b@faa.gov ?
 
If I recall, FlightAware uses data from private citizens with ADS-B receivers connected to the internet to populate much of the information we see. I know that there is a receiver at my home airport sending data to FlightAware. Our nearest ADS-B tower is about 20 miles away. At 1000' AGL, the range would be limited...ground obstructions, trees, etc.

I have old ADS-B tower info showing one at KLAL.
 
Here is a good overview of ADS-B:

https://www.faa.gov/air_traffic/tec...s by,can immediately receive this information.

Key point: aircraft receive traffic data from 2 sources: other aircraft, and ground stations.

For collision avoidance purposes, the relevant data you receive will be directly from other nearby aircraft, and thus not constrained by line of sight to ground stations.

The data displayed on Flight Aware is collected from ground stations, and thus constrained by LOS.

I did not realize that the ground stations broadcast the location of non-ADS-B equipped mode C radar returns.
 
Ed Haywood said:
Here is a good overview of ADS-B:

https://www.faa.gov/air_traffic/technology/equipadsb/capabilities/ins_outs#:~:text=ADS-B Out works by,can immediately receive this information.

Key point: aircraft receive traffic data from 2 sources: other aircraft, and ground stations.

For collision avoidance purposes, the relevant data you receive will be directly from other nearby aircraft, and thus not constrained by line of sight to ground stations.

The data displayed on Flight Aware is collected from ground stations, and thus constrained by LOS.
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Thanks, that explains the Flight Aware gaps we've been seeing.

But we still haven't figured out why my friend's ADS-B In didn't see the helicopters, but did see the fixed wing. Could have been an issue with where the antennas were mounted, I guess.

Ron Wanttaja
 
Out of curiosity, I just checked the history from my receiver and I actually picked up 30 messages from the Warrior on the fatal flight on my receiver at X05. He was still in the Lakeland area at the time I was picking him up, but at 37 miles away I got the messages down to 1900 feet. Below is the last ping I got from him. He was transmitting on 1090 by the way, not UAT.

My antenna is about 20 feet high and there are trees blocking the view towards Winter Haven.

Code: 
{
    "hex": "acc817",
    "flight": "N9221D",
    "alt_baro": 1900,
    "alt_geom": 1975,
    "gs": 103.9,
    "track": 82.3,
    "geom_rate": -64,
    "squawk": "1200",
    "emergency": "none",
    "category": "A1",
    "lat": 28.055172,
    "lon": -81.972279,
    "nic": 8,
    "rc": 186,
    "seen_pos": 27.1,
    "version": 0,
    "nac_p": 8,
    "nac_v": 2,
    "sil": 2,
    "sil_type": "unknown",
    "mlat": [],
    "tisb": [],
    "messages": 30,
    "seen": 24.1,
    "rssi": -15.3,
    "source": "1090",
    "timestamp": 1678213949.908,
    "distance": 37,
    "bearing": 301,
    "bearing_pointer": "↖",
    "recip": 121,
    "recip_pointer": "↘",
    "track_pointer": "→"
  }
 
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wanttaja said:
Thanks, that explains the Flight Aware gaps we've been seeing.

But we still haven't figured out why my friend's ADS-B In didn't see the helicopters, but did see the fixed wing. Could have been an issue with where the antennas were mounted, I guess.

Ron Wanttaja
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My GTX-335 transponder automatically switches between Standby and ALT mode depending on whether the aircraft is on the ground or airborne. When in Standby mode, it does not output ADS-B. I'm not sure what the trigger is for determining airborne status, but would not surprise me if there were a buffer or lag in sensing takeoff.

Edit: a bit of Googling found that various Garmin units use various inputs for Automatic Airborne Determination. One of the them is Ground Speed, with 35 kts being a common threshold. Also, many pilots report a lag of approx 1 minute after takeoff before automatic switching from SBY to ALT. Either could be plausible explanations for low level helo ops not broadcasting.
 
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Ed Haywood said:
My GTX-335 transponder automatically switches between Standby and ALT mode depending on whether the aircraft is on the ground or airborne. When in Standby mode, it does not output ADS-B. I'm not sure what the trigger is for determining airborne status, but would not surprise me if there were a buffer or lag in sensing takeoff.

Also, many pilots report a lag of approx 1 minute after takeoff before automatic switching from SBY to ALT. Either could be plausible explanations for low level helo ops not broadcasting.
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You should change that:

There are approximately 19 pieces of information that your ADS-B is required to transmit through the entire operation – both during flight and while taxiing. Per 14 CFR 91.227 and 91.225, each person operating an aircraft equipped with ADS-B Out must operate this equipment in the transmit mode at all times, unless authorized by the FAA or directed by air traffic control (ATC).
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https://www.faa.gov/air_traffic/technology/equipadsb/installation/know_adsb_system
 
Ed Haywood said:
My GTX-335 transponder automatically switches between Standby and ALT mode depending on whether the aircraft is on the ground or airborne. When in Standby mode, it does not output ADS-B.
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Are you sure it's in STDY and not GND mode while you're taxiing? My Stratus ESG is in STDBY when I power up, but switches to GND mode when I start to taxi.
 
Here is what the install manual for the GTX 335 says. Presumably the "acquisition squitter" meets the FAR requirement.
Altitude mode is automatically selected when the aircraft becomes
airborne, using the units air/ground logic, or when the ALT key is pushed.
Push the ALT key when the GTX 335 is powered off to automatically
energize the unit in altitude reporting mode. While the aircraft is on the
ground and in ALT mode, the transponder does not give Mode A and
Mode C replies, but it does give acquisition squitter and replies to
discretely addressed Mode S interrogations.
While the aircraft is in ALT mode and airborne it will give Mode A,
Mode C, and Mode S replies and give transmissions of acquisition and
extended squitter, to include ADS-B Out.
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Half Fast said:
Are you sure it's in STDY and not GND mode while you're taxiing? My Stratus ESG is in STDBY when I power up, but switches to GND mode when I start to taxi.
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GTX 335 and 345 do not have GND mode. Pilot's guide says to power up in ALT mode and leave it there. Per the excerpt posted above, the unit automatically senses and switches between ground and airborne outputs.
 
My Skybeacon has a setting for the aircraft stall speed, below which the unit assumes the aircraft is on the ground. The default is 40 knots. Might be those helicopters still have higher settings and the signal is shutting down because they slow up early....

Ron Wanttaja
 
Ed Haywood said:
GTX 335 and 345 do not have GND mode. Pilot's guide says to power up in ALT mode and leave it there. Per the excerpt posted above, the unit automatically senses and switches between ground and airborne outputs.
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Ah, so it does sound like you want it to be in ALT mode all the time. Looks like it really does go into a ground mode but without calling it out explicitly.
 
Ed Haywood said:
My GTX-335 transponder automatically switches between Standby and ALT mode depending on whether the aircraft is on the ground or airborne.
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My Garmin GTX 345 and my Avidyne AXP322 (different aircraft) both automatically switch during takeoff and landing. I never manually change or set the modes on these.
 
wanttaja said:
My Skybeacon has a setting for the aircraft stall speed, below which the unit assumes the aircraft is on the ground. The default is 40 knots. Might be those helicopters still have higher settings and the signal is shutting down because they slow up early....
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If "the signal is shutting down because they slow up early" is true then they are in violation of the reg. If it simply shows them on the ground that's what it might do. Not sure how it works for helicopters.

All aircraft must have the ADSB on and transmitting a position if equipped with ADSB. If any equipment is not allowing ADSB to report at all times while in flight or moving on the airport surface that still doesn't make compliance with the regulation an option.

§ 91.227(e)(3)
"The aircraft must transmit its position and velocity at least once per second while airborne or while moving on the airport surface."

Edit to add:
§ 91.227(e)(4)
"The aircraft must transmit its position at least once every 5 seconds while stationary on the airport surface."
 
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Ed Haywood said:
For collision avoidance purposes, the relevant data you receive will be directly from other nearby aircraft, and thus not constrained by line of sight to ground stations.
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If both aircraft are operating at the same frequency (1090 vs 987MHz) or if the ADSB-in hardware is listening to both.
 
Ed Haywood said:
Does anyone even sell an ADS-B receiver that is not dual-band?
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My Avidyne ADS-B receiver was 978 MHz only as the SkyTrax 100B.
The avionics shop was able to apply a software update that upgraded this into a SkyTrax 200 Dual-Band ADS-B IN receiver for total cost slightly under $500. 1090 MHz and 978 MHz. Seemed pretty reasonable as far as avionics costs go. I was surprised it was just a software update.

I am definitely seeing traffic much better now. Either it was not even working properly before and the "upgrade" simply resolved defects or the additional band really makes a decent difference. Either way I find it much more useful now.
 
I did a departure from KGIF this weekend and had a float plane cross above me just off the departure end of the runway. We were in constant communications and visual contact the whole time though. If he hadn't been communicating well it would have not been pleasant. The problem I have with it is that I'm relying on him to communicate well. If he just says "taking off lake whatever" that doesn't help my situational awareness one bit. Fortunately, this pilot was well aware of the runways and how he would be effecting them.

I hadn't heard that type of useful communication in prior visits, I usually have only a vague idea where those guys are even with their radio calls. So, I'm going to assume this accident has made everyone consider how to do better.
 
Salty said:
I did a departure from KGIF this weekend and had a float plane cross above me just off the departure end of the runway.
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Were you using runway 23? That goes directly over the water runway on Lake Jessie.


Salty said:
I hadn't heard that type of useful communication in prior visits, I usually have only a vague idea where those guys are even with their radio calls. So, I'm going to assume this accident has made everyone consider how to do better.
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I certainly hope so. I've heard seaplanes on the KGIF CTAF much more often since the crash and they've been more explicit about where they are and what they're doing.
 
Half Fast said:
Were you using runway 23? That goes directly over the water runway on Lake Jessie.
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No. We departed from 11 and he took off from Lake Hartridge. I stayed low and let him go by above me and then began my climb after he passed.

This was my track, he crossed above me about where the yellow dot is. I was only about 110 feet AGL until he crossed over.

Screen Shot 2023-04-10 at 6.45.50 PM.png
 
Glad you guys were talking. Looks like he was right over the departure end of the runway. Lake Hartridge might not be the wisest place for seaplane take-offs and la dings.
 
Looks like Jack Brown's might have changed their procedure. The last few times I've flown at Winter Haven, the seaplanes were using the KGIF pattern while landing at the seaplane base on Lake Jessie. They were also using radios, which I appreciated.

For example, I was doing some T&Gs on rwy 23 Monday morning. A seaplane joined the downwind for 23, flew the pattern, but leveled out at 300' on final and did a low pass over the runway to land on the lake. A week or so ago, I was on downwind for rwy 5 with a seaplane following me. They flew the pattern, but when on final for 5 they simply landed on Lake Jessie rather than continuing to the rwy 5 threshold.

This seems like a much better plan.
 
Half Fast said:
Looks like Jack Brown's might have changed their procedure. The last few times I've flown at Winter Haven, the seaplanes were using the KGIF pattern while landing at the seaplane base on Lake Jessie. They were also using radios, which I appreciated.

For example, I was doing some T&Gs on rwy 23 Monday morning. A seaplane joined the downwind for 23, flew the pattern, but leveled out at 300' on final and did a low pass over the runway to land on the lake. A week or so ago, I was on downwind for rwy 5 with a seaplane following me. They flew the pattern, but when on final for 5 they simply landed on Lake Jessie rather than continuing to the rwy 5 threshold.

This seems like a much better plan.
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That's great to hear! Apparently they found a way to use radios without having their rights trampled on or their freedoms curbed.
 
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