Flight instructor reported an incursion into class D airspace without a clearance.

Attributes
ACN	1534136
Time
Date	201804
Local Time Of Day	1201-1800
Place
Locale Reference	TTN.Airport
State Reference	NJ
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	Small Aircraft Low Wing 2 Eng Retractable Gear
Operating Under FAR Part	Part 91
Flight Phase	Initial Approach
Flight Plan	None
Person 1
Function	Instructor Pilot Not Flying
Qualification	Flight Crew Flight Instructor Flight Crew Commercial Flight Crew Instrument Flight Crew Multiengine
Experience	Flight Crew Last 90 Days 35 Flight Crew Total 245 Flight Crew Type 47
Events
Anomaly	Airspace Violation All Types Deviation - Procedural Clearance Deviation - Procedural Published Material / Policy

Narrative:

On a training flight with a student; I was helping him practice a simulated single engine approach to land. We came in on a practice ILS 6 into ttn. As I helped him; I realized we were about to enter the class D without having yet called tower. I took the controls; stopped with the single engine training; and I quickly switched to tower and before I could call them; we had entered the airspace and tower called asking who we were. I told them who we were and our intentions to enter the pattern to land. I complied with their instructions to fly heading 100 and enter a left downwind 24. I gave the controls back to my student who flew the pattern as instructed and landed. The contributing factors were a new training scenario with the student who didn't think to call up tower. As the instructor; I got distracted helping the student. I realized the problem when I looked at the moving map and saw how close to the D we were. The corrective actions taken were: following the instructions given by tower and agreeing that we should have contacted them before we entered the D airspace.

Original NASA ASRS Text

Title: Flight Instructor reported an incursion into Class D airspace without a clearance.

Narrative: On a training flight with a student; I was helping him practice a simulated single engine approach to land. We came in on a practice ILS 6 into TTN. As I helped him; I realized we were about to enter the class D without having yet called tower. I took the controls; stopped with the single engine training; and I quickly switched to tower and before I could call them; we had entered the airspace and tower called asking who we were. I told them who we were and our intentions to enter the pattern to land. I complied with their instructions to fly heading 100 and enter a left downwind 24. I gave the controls back to my student who flew the pattern as instructed and landed. The contributing factors were a new training scenario with the student who didn't think to call up tower. As the instructor; I got distracted helping the student. I realized the problem when I looked at the moving map and saw how close to the D we were. The corrective actions taken were: following the instructions given by tower and agreeing that we should have contacted them before we entered the D airspace.

Data retrieved from NASA's ASRS site and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.