Narrative:

At xa:42 we departed lex direct to ZZZ on a southeast heading. Over the air-to-air frequency; aircraft Y announced their position as 15 miles southeast of lexington. We informed aircraft Y of our departure from bluegrass and departing on a southeast heading. Approximately one minute later we changed from tower to departure frequency and were alerted by departure control of the inbound aircraft. Simultaneously; the crew was in contact with [ops.] announcing our departure from lex (I had pin 3 turned off during departure.) the crew was not informed of the inbound aircraft by [ops.] at approximately xa:45 lexington departure updated the location of the inbound aircraft. By this point one searchlight; the position lights; and the strobe lights had been turned on; but visual contact had yet to be established. Aircraft Y announced over air-to-air that they would descend to 1800 feet and I replied that we would climb to 2200 feet. Visual contact was established - and confirmed with aircraft Y - approximately 1 mile out and our paths crossed directly; resulting in roughly 400 feet separation. The TCAS was not functional in this aircraft. The specific reason has yet to be determined; but this failure was accepted as 'normal' by the crew because of a misunderstanding the functionality basics of TCAS. It was explained away as only working in 'certain' airspace environments (i.e. Class B airspace). Upon review of this incident; my research has shown otherwise; thus indicating an equipment failure. This incident suggests the possibility of a systemic issue of unfamiliarity with the function of TCAS and similar non-functioning systems in other aircraft. It is my recommendation that information be disseminated to all crews briefly explaining that TCAS is not dependent upon ground equipment and any failure to identify other aircraft is due to degradation of equipment. Also contributory to this event was the failure of company flight over watch [ops.] to alert crews of close proximity.

Google
 

Original NASA ASRS Text

Title: Pilot of a medical mission helicopter reported an NMAC with another aircraft in the vicinity of LEX. Reporter commented the TCAS seemed to be malfunctioning.

Narrative: At XA:42 we departed LEX direct to ZZZ on a southeast heading. Over the air-to-air frequency; Aircraft Y announced their position as 15 miles southeast of Lexington. We informed Aircraft Y of our departure from Bluegrass and departing on a southeast heading. Approximately one minute later we changed from tower to departure frequency and were alerted by departure control of the inbound aircraft. Simultaneously; the crew was in contact with [Ops.] announcing our departure from LEX (I had pin 3 turned off during departure.) The crew was not informed of the inbound aircraft by [Ops.] At approximately XA:45 Lexington departure updated the location of the inbound aircraft. By this point one searchlight; the position lights; and the strobe lights had been turned on; but visual contact had yet to be established. Aircraft Y announced over air-to-air that they would descend to 1800 feet and I replied that we would climb to 2200 feet. Visual contact was established - and confirmed with Aircraft Y - approximately 1 mile out and our paths crossed directly; resulting in roughly 400 feet separation. The TCAS was not functional in this aircraft. The specific reason has yet to be determined; but this failure was accepted as 'normal' by the crew because of a misunderstanding the functionality basics of TCAS. It was explained away as only working in 'certain' airspace environments (i.e. Class B airspace). Upon review of this incident; my research has shown otherwise; thus indicating an equipment failure. This incident suggests the possibility of a systemic issue of unfamiliarity with the function of TCAS and similar non-functioning systems in other aircraft. It is my recommendation that information be disseminated to all crews briefly explaining that TCAS is not dependent upon ground equipment and any failure to identify other aircraft is due to degradation of equipment. Also contributory to this event was the failure of company flight over watch [Ops.] to alert crews of close proximity.

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.