Phenom 300 Flight Crew reported a critical ground conflict during landing after receiving landing clearance. Tower subsequently issued a go-around call on short final that was not received by the flight crew because the radio had inadvertently been switched to ground control.
Synopsis
Phenom 300 Flight Crew reported a critical ground conflict during landing after receiving landing clearance. Tower subsequently issued a go-around call on short final that was not received by the flight crew because the radio had inadvertently been switched to ground control.
Narrative
I was Pilot monitoring and had just switched frequencies from approach to tower. Visibility was 5 miles in haze; and we were able to see the runway just outside of the FAF (ZZZZZ; RNAV XX). I checked in with tower and we're subsequently cleared to land. I illuminated the landing lights and the PF (Pilot Flying) stated 'cleared to land' after my response of landing clearance to tower. As per usual I dialed in the ground frequency using the rotary knob and had it in standby. At this point we were both focused on landing while getting fully configured. As we continued inbound and got to 500 ft I stated '500 stable' to which the PF stated 'landing'. As we got closer probably about 1-200 ft. the PF stated that there was an airplane almost on the runway but not quite. I looked to see but initially only saw a small airplane like a Cherokee further back due to the center piece of the windshield impeding my view. As we got closer I then did see Aircraft Y really close to the runway and thought that the hold short line was really close to the runway. We continued the landing as we felt it was safe since the Aircraft Y did not seem to be intruding onto the runway. Once we landed; the controller asked if 'Aircraft X was on ground frequency'; I responded 'negative' he then said 'who said negative?' I then responded 'Aircraft X'. He then stated 'tower told you to go-around due to aircraft on the runway and you didn't respond' He then gave us a number to call tower. Once we taxied in; shutdown and accomplished all checklists and duties; we called the tower number. Somehow; the ground frequency had been switched from standby to active but neither of us remember even hearing the chime when frequencies are swapped on the GTC (Garmin Touch Controllers). [The Controller] stated they called us starting at about a 1 mile final to 'go-around' and made several calls after that. We were on ground frequency so did not hear them. We tested the GTC radio frequency swap twice on the ground with no chime; then after a third attempt we got a chime. During the remainder of the flight the chime always sounded when we changed frequencies. Somewhere on final approach after landing clearance; one of us must have inadvertently swapped frequencies on accident and didn't catch it. In my case; unrecognized fatigue may have been a factor that led to a loss of situational awareness. I started the day prior with an [early morning wake up and show time]. My duty time that day was 13:57 minutes. We had a shutdown of XA07 local EST with a show time of XA00 EST the day of the incident. That morning I woke up at XJ30 EST which was XG30 body clock time. I don't believe my body had adjusted fully to the time change at this point; so it is entirely possible that I may have inadvertently touched the GTC without noticing or hearing a chime; due to the effects of an inconspicuous progressing of fatigue even though I felt OK.After this incident; I've started to glance at each frequency change on the upper right PFD to ensure that I'm communicating with the correct controller. I periodically glance at it to ensure I'm where I'm supposed to be. This may be helpful in preventing a future situation such as we had. Also; I will pay closer attention to the chatter on the frequency to see if it makes sense; i.e.) hearing ground or clearance delivery when I should be hearing tower. Lastly; I believe duty time and rest periods have to be managed better in order to keep pilots alert. I now realize after the fact; that fatigue definitely played a role in not catching the frequency change; basically a degradation of situational awareness. Fatigue is insidious and it's usually too late when a person realizes they're fatigued. After a long duty day it normally takes a while to unwind and get adequate rest once a pilot gets to his/her hotel room. To add to this; we usually get up 1-1.5 hours prior to show the next morning to prepare for the duty day ahead so the quality of rest may not beoptimal. I also believe that we should have just called for a go around. As mentioned earlier; while the aircraft didn't look like it was intruding onto the runway from our vantage point; it was close. In retrospect the nose of the aircraft was probably just over the runway edge white marking. Because of this it was unusual; and I know believe if in a similar situation in the future; I will call for a go-around simply because something didn't look right. This would undoubtedly had corrected the incorrect frequency as ground control would have switched us over to tower.
Second reporter narrative
The following comments are not meant to absolve myself of any responsibility - I take full ownership of the conduct of this flight - but to articulate my view of what happened and what was in my thought process as the situation unfolded. Nut shell: We landed on runway XX in ZZZ with our comm radio tuned to ground control frequency. Another aircraft (Aircraft Y) had blundered past the runway XX hold short line at [Taxiway] 1; causing a significant loss of separation. Tower called us several times to go-around; but we never heard them because we were not up on tower frequency. How?:The short answer is that my crew mate (PM) and I do not know how comm 1 switched; or got switched; from tower to ground frequency. Neither do we know how that could have happened without our becoming aware of it. I was PIC and PF (Pilot Flying) in the left seat of a repositioning flight from ZZZ1 to ZZZ. Weather was 210/13G18 5SM HZ SCT015 26/23 29.95. TRACON cleared us for the RNAV XX and switched us to ZZZ Tower. PM checked in with Tower; who cleared us to land runway XX. We both acknowledged landing clearance and PM (Pilot Monitoring) moved the lights switch from taxi to landing; all per our SOPs. So far; so good. I am not sure of the timing; whether right after making contact with Tower or upon receiving landing clearance; but the PM entered the ground control frequency in the comm 1 standby. Doing this is basically de facto SOP: I and nearly every other pilot I fly with do this as a regular habit; to help smooth and safely expedite the transition from landing to taxiing. I believe this is good practice.At some point after receiving our landing clearance; and unbeknownst to us; the ground control frequency swapped from the standby to the active. How that happened is the million dollar question. Obviously; there is no reason for us to deliberately change to ground; and I do not remember either of us making any moves on Comm 1 that could have inadvertently triggered the swap. I have observed the PM is; like me; a 'grinder' who typically uses the old school; rotating and pushable tuning knobs on the GTC (Garmin Touch Controllers) to tune and swap frequencies (vs using the touchscreen method); which requires a bit more conscious and physical effort to change frequencies compared to using the touchscreen. So; it seems unlikely that a 'fat finger' caused the swap; whether it was immediately after entering the ground frequency into the standby or moments later.Did I cause the swap? As PF I wouldn't normally be handling comm 1 during landing. Again; I don't remember touching it but also know that; try as I might; I am not immune to bad habits.Did comm 1 swap frequencies on its own? This also seems unlikely: in my [years and thousands of hours] of Phenom 300 time I have not seen that happen. On the other hand; in that time I have seen and heard of various; one off; unexplained anomalies (Phenomena?) in the Garmin avionics and other systems. Perhaps it's not impossible.In any case; our standard avionics setup has the 'COM Frequency Changed Tone' alert enabled; which should have alerted us to the frequency change. But neither of us heard it. Was it working? Was it inhibited; possibly by the '500' EGPWS call? Did it blend in or get overrun by other things happening; like the '500; stable' and 'landing' call outs? Bad timing? This was our first leg on Aircraft X; after picking it up that morning from maintenance inspections in ZZZ1. We know the frequency changed tone was enabled and working from the start and fairly certain it sounded with the change from TRACON to Tower; but we heard no tone subsequently. After parking at the FBO and while setting up for the next leg; we confirmed the tone was enabled and tested it several times. It mostly worked; however at least twice we got no alert tone when swapping frequencies. Then it worked again consistently with no apparent defects. A switchology issue? Intermittent; and failed at a critical time? Another Phenomenon?A few words about situational awareness: As a professional aviator; I take great pride in enhancing and maintaining the highest level of situational awareness possible. I believe my partner shares the same sentiments. After receiving landing clearance; we had no reason to suspect we were tuned to the wrong frequency. But upon reflection afterwards and with the benefit of hindsight; there were 2 aspects that stood out for me that could have (perhaps should have) triggered an awareness that not all was right. Neither was enough to arouse the 'spidey' gut feeling that would have spurred defensive or corrective action; in this case a go-around. As we descended through 500 ft. AGL and approached the runway; I did notice the controller had a male voice; and seemed to be giving some instructions to aircraft on the ground. You will recall the tower controller that cleared us to land minutes earlier; but this was not a red flag for me because one controller relieving another at a position happens all the time. Hearing ground instructions on tower frequency was not a red flag either; because it is not unusual for one controller to be working multiple positions and frequencies simultaneously. One clue I picked up; but failed to realize the significance of; was that I could hear taxiing aircraft respond to ground instructions on the 'tower' frequency. That is unusual. I even remember thinking the controller had an edge on their voice; agitated by something; and that somebody might be in hot water. Now I know why; and who. The other aspect was the position of the Aircraft Y. Obviously; there is no standard airport; runway; or taxiway layout; and runway hold short lines can be in unexpected locations. Some are marked on airport diagrams; most are not; and some locations are marked inaccurately. Some are deemed Hot Spots. I would say that the runway XX hold short line at [Taxiway] 1X in ZZZ is located in an unusual spot. Its location is not depicted on the Jepp 10-9 chart we use; nor is it marked as a Hot Spot. It is approximately 80-100 yards from the runway XX edge stripe. Although well marked on the ground; the hold short line is difficult; at best; to see in the air from a landing aircraft. As we got closer to the runway; perhaps 100-200 ft AGL; I clearly saw and pointed out the Aircraft Y 'holding short' of runway XX; stationary; and abeam the runway threshold markings. He did appear to be closer than normal to the runway; at an odd angle; but being unfamiliar with that runway/taxiway/hold short configuration; I had no way of knowing that he had actually taxied well past the hold short line; and was; in fact; technically on the runway (for what it's worth; I am certain that no part of his airplane was inside the runway XX edge stripe). Still nothing unusual enough to prompt a go-around. I kept an eye on him and continued the approach. As we passed over the threshold at approximately 50-60 ft. AGL; he was still motionless but I could now see that he was probably past a typical hold short location; and I thought maybe we should report that. Since he wasn't moving; and I was well past him and in the flare; I deemed it safe to complete the landing. As it turned out; there was no need to make that report.As I stated; I work hard at situational awareness and make no excuses for my shortcomings. This was day four of eight for me. I'll never know for certain; but looking back on my previous 3 duty days and rest periods I think it's reasonable to conclude that fatigue played at least a small role in dulling my sense of situational awareness. Although I reported for duty that morning feeling fairly well rested and in a good frame of mind; perhaps I would have perceived and processed these clues as greater threats under different circumstances.Final thoughts: To say the least; this has been a humbling experience. I do my best to guard against complacency; but it is useful to be knocked down a peg or two on occasion; and fortunately this time it happened without loss of life or property. We are human. We can not be perfect; but we can be excellent. I am still working towards that perfect flight.
Source: NASA Aviation Safety Reporting System (public domain). Reports are voluntary submissions and are not verified by NASA.