- FGNavRecord *nav = NULL;
- double d2; // in meters squared
- double min_dist
- = FG_NAV_MAX_RANGE*SG_NM_TO_METER*FG_NAV_MAX_RANGE*SG_NM_TO_METER;
-
- // find the closest station within a sensible range (FG_NAV_MAX_RANGE)
- for ( unsigned int i = 0; i < stations.size(); ++i ) {
- // cout << "testing " << current->get_ident() << endl;
- d2 = distSqr(stations[i]->get_cart(), aircraft);
-
- // cout << " dist = " << sqrt(d)
- // << " range = " << current->get_range() * SG_NM_TO_METER
- // << endl;
-
- // LOC, ILS, GS, and DME antenna's could potentially be
- // installed at the opposite end of the runway. So it's not
- // enough to simply find the closest antenna with the right
- // frequency. We need the closest antenna with the right
- // frequency that is most oriented towards us. (We penalize
- // stations that are facing away from us by adding 5000 meters
- // which is further than matching stations would ever be
- // placed from each other. (Do the expensive check only for
- // directional atennas and only when there is a chance it is
- // the closest station.)
- if ( d2 < min_dist &&
- (stations[i]->get_type() == 4 || stations[i]->get_type() == 5 ||
- stations[i]->get_type() == 6 || stations[i]->get_type() == 12 ||
- stations[i]->get_type() == 13) )
- {
- double hdg_deg = 0.0;
- if ( stations[i]->get_type() == 4 || stations[i]->get_type() == 5 ){
- hdg_deg = stations[i]->get_multiuse();
- } else if ( stations[i]->get_type() == 6 ) {
- int tmp = (int)(stations[i]->get_multiuse() / 1000.0);
- hdg_deg = stations[i]->get_multiuse() - (tmp * 1000);
- } else if ( stations[i]->get_type() == 12 ||
- stations[i]->get_type() == 13 ) {
- // oops, Robin's data format doesn't give us the
- // needed information to compute a heading for a DME
- // transmitter. FIXME Robin!
- }
-
- double az1 = 0.0, az2 = 0.0, s = 0.0;
- SGGeod geod = SGGeod::fromCart(aircraft);
- geo_inverse_wgs_84( geod, stations[i]->get_pos(),
- &az1, &az2, &s);
- az1 = az1 - stations[i]->get_multiuse();
- if ( az1 > 180.0) az1 -= 360.0;
- if ( az1 < -180.0) az1 += 360.0;
- // penalize opposite facing stations by adding 5000 meters
- // (squared) which is further than matching stations would
- // ever be placed from each other.
- if ( fabs(az1) > 90.0 ) {
- double dist = sqrt(d2);
- d2 = (dist + 5000) * (dist + 5000);
- }
- }
-
- if ( d2 < min_dist ) {
- min_dist = d2;
- nav = stations[i];
- }
+ nav_list_type stations;
+
+ flightgear::NavDataCache* cache = flightgear::NavDataCache::instance();
+ int freqKhz = static_cast<int>(freq * 1000 + 0.5);
+ PositionedIDVec ids(cache->findNavaidsByFreq(freqKhz, position, filter));
+
+ BOOST_FOREACH(PositionedID id, ids) {
+ FGNavRecordRef station = FGPositioned::loadById<FGNavRecord>(id);
+ if (!filter->pass(station)) {
+ continue;