You have to recognize here that you are not dealing with an article, not the article "de" but the preposition "de". This preposition is the usual one for the verb "remplir".

• bouteille remplie de vin, ciel rempli de nuages,

Similarly "de" is the preposition used for expressing the relation called "sort".

• drap de lit, maison de campagne, bateau de pêche, salle de classe, larve de papillon, etc.

In the case of "vol de parapentes" the relation is the same; a vol is a set of animals flying together (un vol de moineaux, un vol de corbeaux, …); this has been carried over to the situation of several "parapentes" flying together.

The reason there is no article is that it is suppressed because of the presence of the preposition. Here are details on this practice: l’effacement.

I guess it could be difficult to see the difference for a non native speaker, between the "de" article and "de" preposition.

To answer your question, no, it shouldn’t be "des pistaches" in your example.

"J’ai une calebasse remplie de pistaches" ("I have a calabash filled with pistachios") => preposition

"J’ai un plein sac de pistaches" ("I have a full bag of pistachios") => preposition

"Pistache", in those examples, is envisioned as a content, not as objects.

"Je mange des pistaches ("I eat pistachios") => article

"Je fais griller des pistaches" ("I roast pistachios") => article

Here, it is about "pistachios" as different objects.

I hope my answer give you some clues on how to use "de".