Transponders ON

We are not all in the habit of using transponders on the ground since we do not want to “set off” a TCAS TA or RA for a landing aircraft; however, TCAS units inhibit TCAS TAs and RAs when we are within 500 (+/- 100) feet of the ground.

Our recommendation based on this SAFO is to review your aircraft normal checklists and make sure you set the transponder to ON or ALT in the after start or before taxi checklists. You should also review your after landing checklist to make sure you don’t have a checklist item to turn the transponder to OFF or STBY.

If your thought is that at uncontrolled airports there is no reason to have your transponder set to ON or ALT for taxi operations, you are correct in that there is not an air traffic controller monitoring your movements on the ground; however, having your transponder set to ON or ALT at an uncontrolled airport does not have an ill effect. So rather than try to have two different procedures for operating at a controlled or uncontrolled airport, it is simpler to have a single procedure. The FAA’s recommendation is that procedure should be to have your transponder set to ON or ALT whenever your aircraft is on an airport movement area at all airports.

For all the latest changes with TCAS including information from this SAFO, the NTSB Safety Alert “See and Be Seen: Your Life Depends on It”, and the May 2015 ACAS II Bulletin from Eurocontrol, enroll for our TCAS eLearning module.