The MD-11 shows the following entries when in approach mode.LSK1L : Clean Min 209LSK2L : Slat Ext Min 169LSK3L : Flap 28 Min 156LSK4L : 35/Land VAPP VREF 159 154Can anybody explain what those numbers indicate ?What is meant with VAPP and VREFThanksHubert Werni

The MD-11 shows the following entries when in approach mode.LSK1L : Clean Min 209LSK2L : Slat Ext Min 169LSK3L : Flap 28 Min 156LSK4L : 35/Land VAPP VREF 159 154Can anybody explain what those numbers indicate ?What is meant with VAPP and VREFThanksHubert Werni

Hello HubertThose are the speeds at which your MD-11 aircraft should be at when you (1)do not have any flaps selected,i.e.the aircraft is clean(2)speed at minimum flaps(3)speed at next flaps selecting(4)VAPP=APProach speed,i.e.159kts(5)VREF=will be your landing speed,i.e.154ktsHope this helps.

These are the minimum maneuver speeds. E.g. in your case, with no slats/flaps extended, go below 209 KIAS and you enter the danger zone. So, extend slats before crossing 209 KIAS, and you're on the safe side. With slats extended then, you can go as slow as 169 KIAS (LSK2L) in your example. Same for flaps 28.Vapp is the speed with which you fly the last mile(s) during final approach, and Vref is the speed with which you should overfly the runway threshold. Touchdown speed is usually a little lower than Vref.LSK4L gives you Vapp and Vref for the selected landing flaps setting (35 or 50).Hope this helps.