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Transponder is now to be on Alt at all airports

RV3bpilot

RV3bpilot

Well Known Member
SAFO 15006
Subject: Transponder Use by Aircraft On Airport Movement Areas
Purpose: This SAFO advises all operators and pilots of the need to ensure that transponders are in the altitude reporting mode whenever their aircraft is on an airport movement area at all airports.
Background: The Federal Aviation Administration (FAA) uses airport surface surveillance capabilities at some of the busiest airports in the U.S. to determine aircraft and vehicle location when they are operating on an airport movement area. Runway safety systems, such as Airport Surface Detection Equipment-Model X (ASDE-X) and Advanced Surface Movement Guidance and Control System (A-SMGCS), use data from surface movement radar and aircraft transponders to obtain accurate aircraft and vehicle locations, thereby increasing airport surface safety and efficiency.
Discussion: As the FAA transitions to the Next Generation Air Transportation System, some Airport Surface Detection Equipment-Model 3 systems will be replaced with a multilateration (MLAT)1/Automatic Dependent Surveillance–Broadcast (ADS-B) system, called Airport Surface Surveillance Capability (ASSC). This capability fuses MLAT sensor data with ADS-B aircraft information on FAA certified airport tower controller displays, tracks surface vehicles and aircraft providing information for Air Traffic Control (ATC) services, and is capable of providing data to other external FAA systems,2 including compliance monitoring capabilities.
The effectiveness of ASSC and ASDE-X is dependent on operators equipping and operating cooperative surveillance capabilities (i.e., altitude reporting transponders). Nationwide, airports with ASDE-X report an average of twenty non-compliance transponder events per day, even with airport diagram or Automated Terminal Information Service (ATIS), or both, verbiage directing pilots to operate with transponders on. To proactively address these problems, aircraft operating on all airport movement areas at all airports, not just those that are ASDE-X equipped, must have their transponders on in the altitude
 
This was published in the AIM some time ago, I think as a recommendation. To the best of my knowledge it has not yet made it to the FARs, leaving one branch of tbe FAA complaining about 'non compliance' while the legal branch has not yet told pilots that they have to comply!

Edit: in some ways this makes life easier. I just leave my transponder on ALT all the time, even in non movement areas.
 
Back in the good old days when there was a line up of 35 airplanes in the evening departure from JFK to Europe, ALT was off until just before take off.
Wondering how dozens of aircraft squawking ALT on the ground promotes safety. It sure will fill a controllers screen with useless info.
What am I missing here?
 
As a controller I can see at least one big problem. If you squawk early the computers will start the clock so to speak, especially on IFR departures. When you get airborne it will confuse the system because it thinks you already took off. It can be fixed with just a few key strokes but when you multiply that by 35 as was mentioned, it can become a real problem.
 
David-aviator said:
Back in the good old days when there was a line up of 35 airplanes in the evening departure from JFK to Europe, ALT was off until just before take off.
Wondering how dozens of aircraft squawking ALT on the ground promotes safety. It sure will fill a controllers screen with useless info.
What am I missing here?
Click to expand...

ASDE-X depends on the use of transponders.
 
David-aviator said:
Well that makes sense.
Will every airport with a control tower have such technology?
Click to expand...

They may.

ASDE-X requires its own separate (expensive) radar system, which makes it really only viable for large air carrier airports.

However, there's a new technology (ASSC) based on ADS-B that may make airport surveillance systems much cheaper for smaller airports.

As a pilot, there's no downside to having the transponder on ALT all the time, even on the ground. The only time I turn it off is before shutdown or when instructed to (flying into OSH, for example).
 
Many of us have gotten quite lazy with the newer transponders having automatic mode changing with altitude. I wonder if this means the manufacturers can make an easy software change or I will have to relearn setting my transponder.
 
MarkW said:
Many of us have gotten quite lazy with the newer transponders having automatic mode changing with altitude. I wonder if this means the manufacturers can make an easy software change or I will have to relearn setting my transponder.
Click to expand...

If you have a Mode-S transponder that automatically goes into GND mode, you don't have to do anything. It responds properly to ASDE/ASDE-X/ASSC interrogations.

All of the Dynon transponders and many of the Garmin transponders have that feature.
 
Well now that is cool.
So if we keep an eye on our transponder and it shows alt on the ground we know that we have been interrogated by the system.
 
MarkW said:
Many of us have gotten quite lazy with the newer transponders having automatic mode changing with altitude. I wonder if this means the manufacturers can make an easy software change or I will have to relearn setting my transponder.
Click to expand...

You now want to disable that software and just leave it on ALT all the time.

I think the FAA jumped the gun a bit. By 2020 all of the big guys will have mode S-ES transponders with ADSB-out. One of the TSO rules calls for an automatic switch from a flight mode to a ground mode, using airspeed sensors, airdata info, etc. The ground mode transmits stuff like wing span, so the hope is that a ground based computer will warn when a giant Airbus's wing tip is about to hit someone on an adjacent taxiway. So the S-ES transponders are just left in ALT or Flight mode all the time.

I have no idea how this translates over to those using mode C and a UAT.
 
GTX V8.XX Software

MarkW said:
Many of us have gotten quite lazy with the newer transponders having automatic mode changing with altitude. I wonder if this means the manufacturers can make an easy software change or I will have to relearn setting my transponder.
Click to expand...

Hello Mark,

There is actually a little more to this story. We have been hard at work in response to these changes, and have already fielded some G3X/G3X Touch software changes to make sure our customers are up-to-date and in a position to easily comply. Similarly, the GTX 23ES and GTX 330ES software has undergone changes and testing and even re-certification.

You probably didn't notice, but in G3X software V10.00 one of the changes is listed as "Added support for GTX 23/33/330 software version 8.00." A similar change was implemented in G3X Touch V3.50.

When V8.XX GTX software becomes available, this software incorporates some "mandates" that flowed down on us as transponder manufacturers forcing changes and removal of the GND mode that everyone enjoys in G3X today (which auto transitions to ALT mode).

You will still be able to manually force your transponder into STBY or ON in non altitude reporting mode should you need to, but it will automatically transition to ALT mode both on the ground and in the air without your help in response to these new requirements.

There is a good chance we will be offering free transponder updates at Oshkosh to V8.XX, but the timing hasn't been firmly established for that yet. In the meantime you can continue to use your current GTX software and indeed these transponders do respond to interrogations while on the ground. When you do transition to V8.XX on your transponder, your G3X software is ready and able to work with this new transponder software.

Thanks,
Steve
 
Thanks Steve I look forward to updating my GTX23ES at Oshkosh. Hopefully that will be V8.
 
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