A dynamic parameter that controls the number of minutes prior to the flight plan calculated time of arrival at the meter fix for each aircraft, at which time the tentative calculated landing time (TCLT) is frozen and becomes an actual calculated landing time (ACLT); that is, the vertex time of arrival (VTA) is updated and, consequently, the TCLT is modified as appropriate until frozen, at which time updating is suspended and an ACLT is assigned. When frozen, the flight entry is inserted into the arrival sector's meter list for display on the
sector PVD/MDM (plan view display/main display monitor). The MLDI is used if the filed true air speed is less than or equal to the freeze-speed parameters (FSPD). The VTA is the calculated time of the aircraft's arrival over the adapted vertex for the runway configuration in use. This time is calculated via the optimum flight path using adapted speed segments.