On a related topic, which may interest some, if you have an Avidyne TAS6xx box and your Mode S transponder fails, or gets turned off, the TAS still works. This is not surprising if you know how the system is wired…
Do rolls beneath the base of CAS always gets them excited.
Actually vertical climbing manoeuvres will get TCAS excited as it is projecting the vector, over 5,000 fpm in most aerobatic types.
Ibra wrote:
We used to put aerobatic squawk but later on ATC asked to switch ALT OFF as it still triggers airspace/traffic warmings in ATC screens and may get flagged in TCAS units
Yes me to, they want it both ways.
Do rolls beneath the base of CAS always gets them excited.
Airborne_Again wrote:
No need to turn off the transponder — only to turn off altitude reporting.
We used to put aerobatic squawk but later on ATC asked to switch ALT OFF as it still triggers airspace/traffic warmings in ATC screens and may get flagged in TCAS units
RobertL18C wrote:
Aerobatic aircraft operating under CAS
No need to turn off the transponder — only to turn off altitude reporting.
I do not understand, why the hell someone could leave off an installed transponder. For everyone who has installed any kind of TAS it is a help to see and avoid.
As a TAS6xx owner, I agree.
This thread is worth a read. Some good posts around here.
And if you have a lot of stamina you can read this one 
As mentioned in the thread earlier
1. Aerobatic aircraft operating under CAS
2. Annex 1 aircraft without electrical systems – they will tend to squawk on listening services, but if no radar nearby will switch off to conserve battery
I do not understand, why the hell someone could leave off an installed transponder. For everyone who has installed any kind of TAS it is a help to see and avoid.
The worst I have ever seen was an instructor with his student flying traffic patterns without transponder and without doing the radios, because as mentioned by one of the guys on the field, the radio is recorded and he would have benb billed for the landings although the tower was unmanned at this time. We saw him in the final 3 meters on the right of us, same altitude.
Since this time, when entering a traffic pattern and there is someone without a switched on transponder, I do always ask why and to put it on to make him more visible.
Ground/Airborne is a state. Modes are ON, ALT, and STBY. ON and ALT reply to queries and if ADS-B Out, will broadcast. ON does not include pressure altitude when airborne.. STBY does not reply or broadcast ADS-B Out. The Ground/Airborne state determines the content of the reply for a mode S transponder and the content of the ADS-B Out Broadcast. Depending on the system, the Ground/Airborne State is controlled by Weight on Wheels/An airspeed switch/or GPS data. In the ground state, pressure altitude is replaced with length and wingspan categories for a mode S transponder and different values are broadcast by ADS-B Out. The Ground/Airborne is included as part of the Mode S transponder reply and the ADS-B Broadcast messages. Transponders such as the GTX 345 should be left in the ALT mode at all times unless directed by ATC.
In the US, there are different rules for ADS-B Out and Transponders as to when they must be on. ADS-B Out is required to be in the transmit mode at all times which I interpret as anytime once you enter the movement area.. A transponder is required to be on in controlled airspace. Because of ASDEX at the major airports where transponders need to be on at all times, the current guidance is that transponders should be on at all times on the ground in the movement area. So once you begin to move, the transponder should not be in STBY. In the US. the ADS-B Out may be integral to a mode S transponder or in a separate UAT ADS-B Out system. When they are integral to the transponder (1090ES), that effectively requires the transponder to be on at all times.
ivark wrote:
COMMISSION IMPLEMENTING REGULATION (EU) 2016/1185
….OMG. I break the law every time I fly the Chieftain.
It has two transponders, but you can only switch one on at a time. Where do I go to get flogged and eviscerated?
