Leaving transponders on at non-ASDEX airports?

C150J

C150J

Well-Known Member
Hi guys,

I'm revising some checklists for my operation and was wondering if there was any risk when it comes to leaving transponders on until shutdown, regardless of the airport's surveillance capability. Just trying to simplify/reduce workload/encourage "both heads up taxi" for our guys, and would like to remove an "after landing" checklist item.

I know ALPA has encouraged leaving the devices on to the gate, but I wanted to hear it from the pros. Thanks!

J.
 
Just as long as you cancel at the gate.
The only problem I could think of is them thinking that code is now free to assign to another aircraft and you then squawk it therefore opening their flight plan.
I had this happen to me at IAD of all places and they DO have ground radar.
 
I recenctly got an InFO on this matter. The copy and paste didn't turn out great, but good enough to get the gist.

During recent cockpit enroute inspections, Federal Aviation Administration (FAA)
Aviation Safety Inspectors (ASI) have noticed that some operating procedures direct flightcrews to
select traffic advisory/resolution advisory (TA/RA) during all surface movement operations. This
procedure is contrary to the FAA TCAS guidance as discussed in Advisory Circular (AC) 120-55C,
Air Carrier Operational Approval and Use of TCAS II.​

Discussion:
TCAS II operation on the airport surface provides no safety benefit, except when
approaching or taxiing onto an active runway. Routine ground operations with the transponder selected
to TA-ONLY or TA/RA enables TCAS II to interrogate other aircraft at high power levels. This
unnecessarily contributes to 1090 MHZ frequency congestion. Routine operation of TCAS II on the
ground can degrade:
 Performance of ATC radars
 Surveillance performed by airborne TCAS II units in the vicinity of your aircraft
Operating with the transponder on (XPNDR or ON) is sufficient to ensure that aircraft are visible to
ATC surface surveillance systems.
Recommended Action: ​

​

Directors of safety, directors of operations, chief pilots, fractional ownership
program managers, training managers, and operators of aircraft should emphasize the importance of
adhering to the guidance found in AC 120-55C and the procedures listed below.
Departures. Select transponder to XPNDR or ON during pushback. Select TA/RA when
taking the active runway.
Arrivals. Select transponder to XPNDR or ON after clearing the active runway. Select STBY
or OFF per company operating procedures at the completion of the flight.​

​
Click to expand...

​
 
Those of us who have TAS/TCASI/TCASII but no radar altimeter or "gear down" sensing (gear are welded) kindly request that you turn your transponder off on the ground unless you absolutely must have it on ;)

The TSO does not allow us to shut the traffic system off unless we have those things, so when we're on short final we get "TRAFFIC TRAFFIC!" once for every person burning the transponder in the runup area.
 
C150J said:
Hi guys,

I'm revising some checklists for my operation and was wondering if there was any risk when it comes to leaving transponders on until shutdown, regardless of the airport's surveillance capability. Just trying to simplify/reduce workload/encourage "both heads up taxi" for our guys, and would like to remove an "after landing" checklist item.
Click to expand...

Curious, how would the one-second it takes to go to STBY make extra workload? "Heads up for taxi" doesn't necessarily mean you have to be sitting at the position of attention with eyes locked forward. :)

I know ALPA has encouraged leaving the devices on to the gate, but I wanted to hear it from the pros. Thanks!

J.
Click to expand...

Id want to hear it from pros, not ALPA, too. :D
 
I got in the habit of leaving them on all the time because I flew into DFW and IAH and a few other airports that have that ground radar and it got annoying to remember which airports did and which airports didn't have it. But on the newer garmin transponders it automatically turns itself off and on.
 
MikeD said:
Curious, how would the one-second it takes to go to STBY make extra workload? "Heads up for taxi" doesn't necessarily mean you have to be sitting at the position of attention with eyes locked forward. :)
Click to expand...

:)

I probably over-emphasized the "heads-up" aspect: mainly going for extreme simplicity and cross-platform compliance. I'm trying to pare down our checklists to the maximum extent possible. I have removed a lot of the blatantly unnecessary stuff (e.g., "headsets - off") and now that I'm down to the final items, I'm starting to question their legitimacy. Now that is appears that operating in TA/RA is detrimental (thanks DC3Flyer!), I'll definitely keep it there.

On a side note, data from my last operation indicated that the majority of surface deviations were immediately after landing. Crew narratives usually indicated that one pilot was in the middle of running a checklist when the deviation occurred. This isn't to say that flicking a transponder is a causal factor, but if it's not necessary, why have it there? Figured I'd ask.
 
Leaving your transponder in "ALT" annoys the bejeezis out of me at work, because I'll still get a TA on the TAS. On short final...

In my airplane, ground mode is automatic upon reaching 30 knots ground speed.
 
Can't speak for other operators, but at the Borg Collective, OKA Delta, they are turned to RA/TA prior to push and off on shutdown. All of the units have inhibitors that automatically downgrades to ON while on the ground. Besides ASDX, it also interfaces with a program the company uses called Autobahn, so the ramp towers at hub airports can see where we are.
 
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