Narrative:

I was in contact with approach and was cleared for the RNAV runway xx approach to ZZZ. There was a temporary tower in use at ZZZ; and when I was between zzzzz and ZZZZZ1; I was handed off to the tower. I contacted the tower and advised that I was RNAV xx inbound at 2;600 ft. The tower replied 'not in contact; cleared to land.' a cessna citation called the tower; advising 'left downwind; runway xx.' I was not in visual contact with the ground or the runway; but in between cloud layers. I saw the citation depicted on the ads-B link on my primary flight display. The distance between my aircraft and the citation continued to close. I was still on the RNAV approach when I received a traffic alert. I saw the citation close in and turn across my flight path to intercept the final approach course. I made an evasive turn south off of the approach course to go behind the citation. I advised the tower of the conflict and asked to be vectored out and back to the approach. The tower handed me off to approach who provided vectors back to the approach which was completed on the second attempt.I know the citation was not in visual conditions because I could not see the runway and both of us were in the same place. I believe the citation lost visual contact with the runway but did not advise the tower at ZZZ or approach and decided to continue and intercept the final approach course without an instrument clearance. I believe the citation crew were in a hurry to get to the airport to pick up passengers.

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Original NASA ASRS Text

Title: BE36TC pilot reported experiencing an NMAC with another aircraft on approach.

Narrative: I was in contact with Approach and was cleared for the RNAV Runway XX approach to ZZZ. There was a temporary Tower in use at ZZZ; and when I was between ZZZZZ and ZZZZZ1; I was handed off to the Tower. I contacted the Tower and advised that I was RNAV XX inbound at 2;600 ft. The Tower replied 'Not in contact; cleared to land.' A Cessna Citation called the Tower; advising 'Left downwind; Runway XX.' I was not in visual contact with the ground or the runway; but in between cloud layers. I saw the Citation depicted on the ADS-B link on my primary flight display. The distance between my aircraft and the Citation continued to close. I was still on the RNAV approach when I received a traffic alert. I saw the Citation close in and turn across my flight path to intercept the final approach course. I made an evasive turn south off of the approach course to go behind the Citation. I advised the Tower of the conflict and asked to be vectored out and back to the approach. The Tower handed me off to Approach who provided vectors back to the approach which was completed on the second attempt.I know the Citation was not in visual conditions because I could not see the runway and both of us were in the same place. I believe the Citation lost visual contact with the runway but did not advise the Tower at ZZZ or Approach and decided to continue and intercept the final approach course without an instrument clearance. I believe the Citation crew were in a hurry to get to the airport to pick up passengers.

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.