The ADF displays the direction to the NDB on the Relative Bearing Indicator in the cockpit.
Non directional beacons (NDBs) are old-school navigational aids for pilots, but are still very much in use in the UK for instrument procedures and en-route navigation. On this flight, I practise tracking to and from NDBs, and fly an instrument hold at Southend.
You’d think in the days of GPS, ground based radio navigation was a thing of the past. Here in the UK, this couldn’t be further from the truth. While elsewhere, notably the USA, GPS navigation and GPS instrument approaches are replacing ground based systems, the UK has been slow to adopt the technology. As we currently stand, the vast majority of instrument procedures to UK GA aerodromes require the carriage of an automatic direction finder (ADF), which is used to receive the NDB transmissions. Quite often, as in the case of Southend for example, they’re used as the initial approach fix, for the procedure, and the missed approach.
While NDBs are the simplest and cheapest form of ground based navigation system, to interpret their signals in the air requires skill and practise. If we’ve become accustomed to VORs and localisers, which can tell you at a glance where, in relation to the beacon, you are, tuning the ADF into an NDB will likely give you a headache. This is because, in the case of NDBs, the pilot has to do some mental gymnastics to work their relative position to the beacon.
The video below shows you how I track two courses to NDBs, and how I fly an NDB hold at Southend. During this flight, I also did a touch and go at Lydd.
You can view the GPS track of this flight here.
Turning downwind at lydd
Video: NDB tracking & NDB holds
Video: Part 2/2 – tracking from an NDB and correcting track error