Narrative:

I was moving over to take radar (TR)/controller in charge. Aircraft X was on a local IFR flight plan (cleared to ksux via radar vectors) for practice ILS approaches. As I plugged in; [controller a] asked aircraft X how this approach would terminate. No response by the pilot. [Controller a] made several unanswered transmissions and I attempted to reach aircraft X on the PET2000 portable radio located in the tower cab. No response was received by us. I observed aircraft X's mode C then drop off their full data block and the target displayed isr. Aircraft X was then observed making a right turn back inbound to ksux. I relieved [controller a] from the TR position; [controller a] remained on as controller in charge; and verified with [controller B] that aircraft X was cleared to land on rwy 13 which was approved by [controller B]. I gave an unanswered broadcast to aircraft X on TR frequency that tower advised aircraft X was cleared to land on rwy 13. [Controller B] on local control (local) position began preparing to send light gun signals to the aircraft as aircraft X approached rwy 13. The pilot of aircraft X then called the tower via the commercial telephone line; stating they had lost their alternator and their electrical equipment was becoming inoperative. I gave aircraft X their landing clearance via telephone and asked if the pilot required any assistance. The pilot responded no assistance was needed. I then passed the telephone off to [controller B] on the local control position and [controller B] remained on the telephone with the pilot. Aircraft X landed without incident and taxied to the ramp under their own power. No recommendations. Current procedures were adequate for handling the incident.

Related reports:

Google
 

Original NASA ASRS Text

Title: SUX Controller reported a GA aircraft lost communications during practice IFR approach.

Narrative: I was moving over to take Radar (TR)/CIC. Aircraft X was on a local IFR flight plan (cleared to KSUX via radar vectors) for practice ILS approaches. As I plugged in; [Controller A] asked Aircraft X how this approach would terminate. No response by the pilot. [Controller A] made several unanswered transmissions and I attempted to reach Aircraft X on the PET2000 portable radio located in the tower cab. No response was received by us. I observed Aircraft X's mode C then drop off their full data block and the target displayed ISR. Aircraft X was then observed making a right turn back inbound to KSUX. I relieved [Controller A] from the TR position; [Controller A] remained on as CIC; and verified with [Controller B] that Aircraft X was cleared to land on Rwy 13 which was approved by [Controller B]. I gave an unanswered broadcast to Aircraft X on TR frequency that tower advised Aircraft X was cleared to land on Rwy 13. [Controller B] on LC (Local) position began preparing to send light gun signals to the aircraft as Aircraft X approached Rwy 13. The pilot of Aircraft X then called the tower via the commercial telephone line; stating they had lost their alternator and their electrical equipment was becoming inoperative. I gave Aircraft X their landing clearance via telephone and asked if the pilot required any assistance. The pilot responded no assistance was needed. I then passed the telephone off to [Controller B] on the LC position and [Controller B] remained on the telephone with the pilot. Aircraft X landed without incident and taxied to the ramp under their own power. No recommendations. Current procedures were adequate for handling the incident.

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.