If you are approaching the runaway too fast the AoA will be reduced and the up arrow will be illuminated.
If your approach flight is to slow your AoA will be increased and the down arrow will illuminate.
You should aim to be descending at a rate of 500ft/min.You can gauge your exact descent rate using the vertical velocity scale on the HUD in LND mode. It is adjacent to the altitude tape and labelled with either B or R depending on the altitude gauge setting (barometric/radar). Adjust the rate of descent using the throttle and adjust your speed by raising or lowering the nose of the plane. In the final few seconds before touchdown it is more important to focus on the runway, conditions allowing.
Trust your eyes over the instruments because the information they provide is rarely contradictory. As you descend through the last 50ft raise the nose of the aircraft a little. On touchdown immediately throttle down, activate the wheel brakes and use the rudder to steer. "
