The CAA recommends that a suitably accredited FDD is nominated as a deputy FDD to the primary FDD. 
The deputy should be familiar with all aspects of the planning of the specific Flying Display and be aware of and prepared for any duties expected of them on the day of the event.  This information is available in CAP 403, Chapter 8.

An appropriately accredited FDD can act as Deputy FDD to provide resilience for an event.  This individual (or individuals) must be named on the:

• application for a Permission (CAA regulated events) 
  and confirmed in the post event report (SRG 1305) as having taken an active in the planning and execution of the specific Flying Display.
  
  or the
• RA2335 Form 1 (for MAA regulated events)
  
  

A deputy FDD's currency status can be reset when they:

• are nominated on the application for Permission / Form 1,
• take an active part in the planning and execution of the Flying Display,
• are in attendance for the duration of the Flying Display,

The currency status for the deputy FDD can be reset provided that the primary FDD:

• ensures that the nature of the active role and precise level of participation of the deputy FDD is recorded in the Post-Display Feedback Form (SRG1305 / Form 4); 
• records that the Deputy FDD intends to use this event to reset their currency status.    

The responsibility for recording this information on the form rests with the primary FDD in conjunction with the deputy FDD and not the CAA/MAA.

A tier-1 or tier-2 accredited FDD can 'shadow' the primary FDD of a higher tier event to build experience.  This 'shadow' role can be used to improve the level of competence or with a view to upgrading to a higher tier in the future.  The primary FDD should record the level of participation of the 'shadow' FDD in the SRG1305/Form 4 to enable the CAA/MAA to properly assess the level of experience of the individual.

Unless the primary FDD is a 'mentor', they should not comment on the ability or performance of the shadow FDD but limit their comments to their participation level (ie the level of their involvement in the planning and/or execution of the Flying Display).

If the primary FDD is a 'mentor', the 'shadow' FDD should ensure that the participation in the planning and/or execution of the Flying Display is appropriately logged and countersigned by the primary FDD so that any experience gained can be demonstrated at the time of application for upgrade.

Where an FDD acts in the capacity of primary or deputy FDD their 2-year currency status resets at the tier for which the event was performed.  

For example, if a tier-3 FDD conducts a tier-2 Flying Display their 2-year currency will only reset at tier-2. 

To reset their tier-3 currency, they will need to complete a tier-3 Flying Display. 

FDDs who are current but have forfeited privileges may be re-accredited to their previous tier by shadowing an appropriately accredited FDD at a Flying Display. Once satisfactory evidence has been submitted to the CAA GA Unit, previously held privileges may then be restored.

Successful completion of the FDD Accreditation Course will automatically reset both the status of the 3-year FDD qualification validity and the 2-year currency at the tier for which they are accredited.