bio161:
Flying out of EGLL i noticed that ALL the departures of LHR are "still" conventional departures, not even RNAV overlays.
It made me thinking that as soon as one nav aid goes down they have to provide radar guided sid (even if this is actually standard in LHR
)
What kind of FMS are you using? Must be a very basic model. In modern FMSes all ground-based navaid SIDS (and STARs) are coded to be flown with LNAV. Here is an "entry level" light airplane Garmin G-1000:
