Small Aircraft
Air Traffic Control Fully Certified
Air Traffic Control Time Certified In Pos 1 (yrs) 2.5
Communication Breakdown; Confusion; Time Pressure
ATC Issue All Types; Conflict Airborne Conflict; Deviation - Track / Heading All Types; Deviation / Discrepancy - Procedural Clearance; Inflight Event / Encounter VFR In IMC; Inflight Event / Encounter Weather / Turbulence
Air Traffic Control Provided Assistance; Flight Crew Became Reoriented
Human Factors; Weather; Procedure
Aircraft X departed Runway XL at ZZZ VFR. I heard him request clearance from ground prior to assuming the Local Control position.  My understanding is that he requested a VFR clearance to the west.  When the Ground Controller advised him that the ceiling was 011; he said he would stay at 010 and continue 20-30 miles to the west where it would improve and he could climb VFR to 045.   There was some discussion about his VFR abilities on the inbound leg from the prior controllers; but I had just started my shift.  When he called ready for departure; I cleared Aircraft X on course; because I didn't want to assign a heading in the marginal weather.  As I observed Aircraft X continue to turn to the south towards inbound traffic landing Runway XR (Aircraft Y and Aircraft Z); I asked Aircraft X if he could maintain VFR on a westbound heading.  He was near the taller buildings of ZZZ and I should have restricted him north of them from the onset; but he said he could.  I had him in sight as Aircraft Y landed.  He was almost in a XL downwind position.  Shortly thereafter; he said he was unable to maintain VFR and wanted an IFR clearance.  I told him I was unable to provide one at the moment and he said he was climbing.  He continued to want to track SSW bound toward the aircraft on final.  I tried to get him to turn away from TRACON final airspace; but he was climbing above his clearance limit into it.  The CIC had advised TRACON before he departed that he might have issues. Lateral separation was maintained with Aircraft Z as Aircraft X exited the airspace to the WNW when asked; he replied he was not certified or capable of IFR flight.  Later; he changed his answer.  I tried to coordinate with TRACON for the IFR clearance; but the ear-piece in my headset has been having intermittent issues so I couldn't hear what they were saying; and while using the speaker; the feedback was causing too much distortion to be usable.  After reviewing the incident; Aircraft X said they were back VFR but I was still stuck on trying to get them an IFR clearance.  I coordinated again with TRACON as he was leaving my airspace and entering the shelf below the Bravo; telling the Controller that I couldn't figure out what Aircraft X wanted.  They told me to switch him to them; so I did.  Aircraft X landed at ZZZ1 shortly thereafter.I was aware that this aircraft may encounter difficulty; yet I wasn't fully prepared for how I would process it.  I should have asked more questions before he departed instead of making the assumptions I did.  I assumed he would stay north and/or below final airspace based on his request to depart to the west at 010.  He did neither.  I should have had a better understanding of where he wanted to go; and then assisted him in getting there with my knowledge of local procedures.  I should have restricted him with 'no further south than 270 heading' or similar. If he had been on a heading that direction away from other traffic and still had trouble maintaining VFR; at least there would have been more options to help.  Once he encountered difficulty; I tried to be helpful and safe; but the accent and use of English made it challenging to fully understand what was being asked or answered.  I should get my headset looked at - though I've honestly been putting it off because of the COVID-19 restrictions.  As far as I know; they're locked away.   But hopefully there are some elsewhere or someone has safe access to them.  As a bit of an aside; this is the third headset malfunction in a matter of months; so the re-manufactured headsets are really not holding up well and I think it should be noted.
Local Controller reported an aircraft departed wanting to fly just under the clouds; but encountered IFR and the pilot was not certified for IFR flight.