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UK Civil Aviation Regulations

These are published by the CAA on our UK Regulations pages. EU Regulations and EASA Access Guides published by EASA no longer apply in the UK. Our website and publications are being reviewed to update all references. Any references to EU law and EASA Access guides should be disregarded and where applicable the equivalent UK versions referred to instead.



On Job Training Instructor (OJTI) Synthetic Training Device Instructor (STDI) and Assessor endorsements.

Applications for the issue, revalidation, and renewal of OJTI/STDI and Assessor endorsement are made on form SRG 1415.

Assessor application requirements

Before applying air traffic controllers (ATCOs) must ensure they meet the following requirements:

  • has exercised the privileges of an air traffic controller licence for at least two years
  • within the year preceding the application has successfully completed a CAA approved assessor course

Assessor revalidation

An Assessor endorsement is valid for three years.

An Assessor endorsement may be revalidated if the following requirements are met:

  • The successful completion refresher training on assessment skills and on current operational practices during its validity period

Refer to administrative requirements below regarding revalidation applications.

Assessor renewal

When an Assessor endorsement has expired, it may be renewed if the following requirements are met:

  • received refresher training on assessment skills and on current operational practices
  • successfully passed an assessor competence assessment within the year preceding the application for renewal

OJTI application requirements

Before applying ATCOs must ensure they meet the following requirements:

  • hold an air traffic controller licence with a valid unit endorsement
  • has exercised the privileges of an air traffic controller licence for a period of at least two years immediately preceding the application. This period can be shortened to not less than one year by the CAA when requested by the training organisation
  • within the year preceding the application, has successfully completed a CAA approved practical instructional techniques course

OJTI revalidation

An OJTI endorsement is valid for three years.

An OJTI endorsement may be revalidated if the following requirements are met:

  • hold an air traffic controller licence with a valid unit endorsement
  • has successfully completed refresher training on practical instructional skills during its validity period

Refer to administrative requirements below regarding revalidation applications.

OJTI Renewal

When OJTI endorsement has expired, it may be renewed if the following requirements are met:

  • hold an air traffic controller licence with a valid unit endorsement
  • received refresher training on practical instructional skills
  • successfully passing a practical instructor competence assessment within the year preceding the application

STDI Application requirements

Before applying ATCOs must ensure they meet the following requirements:

  • has exercised the privileges of an air traffic controller licence in any rating for at least two years
  • within the year preceding the application have successfully completed a CAA approved practical instructional techniques course

STDI revalidation

An STDI endorsement is valid for three years.

An STDI endorsement may be revalidated if the following requirements are met:

  • by successfully completing refresher training on practical instructional skills and on current operational practices during its validity period

Refer to administrative requirements below regarding revalidation applications.

STDI Renewal

When STDI endorsement has expired, it may be renewed if the following requirements are met:

  • receiving refresher training on practical instructional skills and on current operational practices
  • successfully passing a practical instructor competence assessment within the year preceding the application for renewal

Administrative requirements

Refresher training for the revalidation for Assessor/OJTI and STDI endorsements may be carried out at any time during the endorsement’s validity period of three years.

If the application for the revalidation for Assessor/OJTI and STDI endorsements is made within the 90-day period prior to the expiry date, the new endorsement will be issued from the expiry date.

Applications made outside the 90-day period will result in the endorsement being issued from the date of completion of the refresher training.

It is therefore recommended that applications are submitted within the 90 days prior to the current endorsement expiry date to maximise the validity period.

Refresher training towards revalidation of the endorsements should be planned to allow enough time prior to the expiry of the endorsement for the application to be submitted to the CAA.

Licence holders must not engage in any OJTI, STDI or Assessor privileges without such endorsements being current within their licence unless they are in possession of evidence that an eight-week grace period, pending endorsement issue, has been granted by a CAA ATS Inspector (Operations).