Is the authorisation to supply fuel by means of canisters obtained under the previous order still valid?

No. From 2 January 2021, all authorisations granted in accordance with the Order of 10 March 1988 will cease to be valid, so it will be necessary to have the new responsible declaration.

The responsible declaration can be submitted telematically through the following procedure:

 https://sede.seguridadaerea.gob.es/oficina/tramites/acceso.do?id=84.