def METHOD_NAME(self, bit):
    '''send some terrain data'''
    lat = self.current_request.lat * 1.0e-7
    lon = self.current_request.lon * 1.0e-7
    bit_spacing = self.current_request.grid_spacing * 4
    (lat, lon) = mp_util.gps_offset(lat, lon,
                                    east=bit_spacing * (bit % 8),
                                    north=bit_spacing * (bit // 8))
    data = []
    for i in range(4*4):
        y = i % 4
        x = i // 4
        (lat2,lon2) = mp_util.gps_offset(lat, lon,
                                         east=self.current_request.grid_spacing * y,
                                         north=self.current_request.grid_spacing * x)
        alt = self.ElevationModel.GetElevation(lat2, lon2)
        if alt is None:
            if self.terrain_settings.debug:
                print("no alt ", lat2, lon2)
            return
        data.append(int(alt))
    self.master.mav.terrain_data_send(self.current_request.lat,
                                      self.current_request.lon,
                                      self.current_request.grid_spacing,
                                      bit,
                                      data)
    self.blocks_sent += 1
    self.last_send_time = time.time()
    self.sent_mask |= 1<<bit
    if self.terrain_settings.debug and bit == 55:
        lat = self.current_request.lat * 1.0e-7
        lon = self.current_request.lon * 1.0e-7
        print("--lat=%f --lon=%f %.1f" % (
            lat, lon, self.ElevationModel.GetElevation(lat, lon)))
        (lat2,lon2) = mp_util.gps_offset(lat, lon,
                                         east=32*self.current_request.grid_spacing,
                                         north=28*self.current_request.grid_spacing)
        print("--lat=%f --lon=%f %.1f" % (
            lat2, lon2, self.ElevationModel.GetElevation(lat2, lon2)))