Non Directional Beacons

Ensuring compliance with standards and recommended practices


Non-Directional Beacon (NDB) systems provide a navigation capability to suitably equipped aircraft and therefore need to comply with the Standards and Recommended practices (SARPs) in ICAO Annex 10 Volume 1, Chapter 2 (General Provisions for Radio Navigation Aids) and Chapter 3 Section 3.4 (Specification for non-directional radio beacon).

Under the terms of Article 205 of the UK Air Navigation Order all civil MF Non-Directional Beacon (NDB) installations, intended for use in the provision of an Air Traffic Service in the UK, require approval by the CAA. We are able to provide a number of compliant services to assist NDB owners to demonstrate that they meet these SARPs.

What measurements are needed?

Your NDB will need the following parameters measured to demonstrate compliance with the ICAO SARPs:

  • Field Strength
  • Centre Frequency
  • Modulation Depth
  • Morse Ident Transmitted
  • Modulation Frequency

Types of measurement service

1. Annual Off Air Monitoring

This service is carried out at one of NATS facilities on a monthly basis by specialist trained NATS engineers. The specific parameters of the customer’s NDB system, needed to demonstrate compliance with the ICAO SARPs, are measured and recorded. Twelve detailed monthly reports are provided to the customer along with notification of any non compliance in any one month.

2. Ad-Hoc Off Air Monitoring

This service is only available to those customers who subscribe to the Annual Off-Air Monitoring service. Following a failure of the NDB system, or a loss of confidence in its performance, NATS specialist trained engineers can carry out a pre-arranged one off measurement of the customer’s NDB system. As in 1 above, the specific parameters measured are recorded and a detailed report is provided to the customer.

3. Beacon Commissioning

This service is carried out by specialist trained NATS engineers prior to a new NDB system entering operational service or prior to re-instating an NDB system after a prolonged outage. A series of measurements are undertaken at various locations in the vicinity of the customer’s NDB to record the average field strength (and any other specific parameters if required) at the NDB’s Distance Of Coverage (DOC) and thereby demonstrate compliance with the ICAO SARPs. A report detailing the results and supporting information is provided to the customer.

4. General Enquiry

This service is for all other NDB related issues.

How can we help you?

We can help by providing you with any one of the measurement services described above and advise you on ICAO SARPs compliance.

We operate a number of NDB systems to support our own operation and our detailed understanding of the services that you may require should give you the confidence to proceed in the knowledge that you will be provided with a detailed report to demonstrate that your NDB system is compliant with the ICAO SARPs, or if not, what needs to be done for your NDB system to become compliant.

Where can we provide measurement services?

The availability and content of measurement services is dependent on the location of the NDB system.

In simple terms, we can provide:

  • Annual Off Air Monitoring and Ad-Hoc Off Air Monitoring services for all NDB systems that fall within the range of our measuring sites, which currently geographically covers most of the UK. Please make a ‘General Enquiry’ if you would like us to confirm whether we can offer you these services prior to completing an application form.
  • The Beacon Commissioning service at any location in the UK.

How much will it cost?

  • Annual Off Air Monitoring Service - £500 plus VAT
  • Ad-Hoc Off Air Monitoring Service - £62 plus VAT
  • Beacon Commissioning Service - £3,000 plus VAT

You can submit an application and pay online with a credit card.

Contact us

Please contact us if you have any questions:

  • By completing this form, you are consenting to NATS holding your personal information. For further details on how NATS manages your personal information please see our privacy notice.

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