1201alarm
The following is from section 5-4 of the FAA Airman Information Manual (AIM)
https://www.faa.gov/air_traffic/publ...section_4.html
When operating to parallel runways separated by less than 2,500 feet, ATC will ensure approved separation is provided unless the succeeding aircraft reports sighting the preceding aircraft to the adjacent parallel and visual separation is applied.
Separation Responsibilities. If the pilot has the airport in sight but cannot see the aircraft to be followed, ATC may clear the aircraft for a visual approach; however, ATC retains both separation and wake vortex separation responsibility. When visually following a preceding aircraft, acceptance of the visual approach clearance constitutes acceptance of pilot responsibility for maintaining a safe approach interval and adequate wake turbulence separation.
(As an aside, you can also be cleared for a visual approach with only the preceding aircraft, but not the airport in sight.)
For the people who insist that an IFR aircraft should always be afforded an IAP, please note what I've highlighted in bold.
When landing at airports with approach control services and where two or more
IAPs are published, pilots will be provided in advance of their arrival with the type of approach to expect
or that they may be vectored for a visual approach. This information will be broadcast either by a controller or on
ATIS.