Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Commercial
Flight Crew Last 90 Days 4; Flight Crew Total 1500; Flight Crew Type 650
Confusion
Deviation / Discrepancy - Procedural Clearance; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural Landing Without Clearance; Ground Incursion Runway; Inflight Event / Encounter Other / Unknown
Air Traffic Control Issued Advisory / Alert; Flight Crew Returned To Clearance
Environment - Non Weather Related
[In the] morning; I was taking another certificated pilot for a familiarization ride in Aircraft X. He was a private pilot with a few hours in high performance aircraft and wanted to see how Aircraft X performed on a relatively hot summer day at altitude. After departing Runway 30R I requested closed pattern for touch-and-go landings. Due to the extreme smoke and haze conditions from the many forest fires across Colorado; and the number of aircraft in the traffic pattern at the same time; Tower requested that I fly runway heading until advised to turn crosswind. I was cleared to turn left and enter left downwind for Runway 30L. Being so far west of the airport; the runway was no longer visible from pattern altitude as I turned back towards BJC.As I entered downwind; Tower began calling traffic and I was unable to see many of the other aircraft. Tower advised that; due to poor visibility and heavy traffic; they would call my base. By the time Tower cleared me to turn base; I was well east of the normal 'key' position in the pattern. Tower cleared me for the option on Runway 30L; but as I turned to final; all I could see was Runway 30R. The threshold for Runway 30L is displaced quite a ways west of the threshold for Runway 30R. Runway 30L is also considerably shorter and narrower than Runway 30R; and in the smoke and haze; Runway 30L was not even in my field of view on final approach. I did not even realize that I had landed on the wrong runway until after takeoff when Tower asked me if I remembered being cleared for landing on Runway 30L. Another Tower Controller gave me a phone number to call and I called the Tower immediately after I landed.
Pilot Flying reported smoke obscuring flight whilst in the pattern; leading to a landing on the wrong runway.