Trailing cone

A trailing cone (also a trailing static cone or, incorrectly, a trailing wire) is an aviation calibration tool first developed and tested in the 1950s and 1960s as a simple means of determining or calibrating the static pressure (altitude reporting) of an aircraft's pitot-static system.¹ It does this by giving an accurate measurement of the ambient atmospheric pressure (static pressure) well clear of the aircraft's fuselage.² The trailing cone system typically trails at least one fuselage length behind the aircraft via a high-strength cable containing a tube or attached to a tube to cone or similar stabilizing device at the end. Static pressure is measured forward of the cone by several static ports.³ The cone stabilizes and aligns the ports relative to the freestream airflow.⁴

As stated in FAA Advisory Circular AC 91-85A:

• Precision tracking radar in conjunction with pressure calibration of atmosphere at test altitude
• Chase aircraft
• Any other method acceptable to the approving authority