Who pilots an aircraft that is on a delivery flight? Right about now (Jan 28, 2016, 08:12 UTC), a Boeing 737-8AS is cruising over Manitoba/Nunavut on a delivery flight from Seattle Boeing Field (BFI) to Dublin Airport (DUB). The flight is labelled RYR800F, and is clearly a delivery flight for the European low-cost airline Ryanair.



I have always wondered who flies the plane in such situations. I would appreciate if you could give me a few insights into how these events are managed by the manufacturer and the Company. I envision the following cases, but which one of them, or combination of them, is true?

1) The plane is flown by a special pilot unit of the buying Company, which flies to the manufacturer's logistic airport, checks for conformity, signs a few documents, and then flies the plane to the Company's headquarters or hub;

2) The plane is flown by a special pilot unit of the manufacturer. They fly the plane to the Company's headquarters or hub, then meet the buyer to check for conformity and sign the documents. Eventually, the pilot unit flies back to manufacturer's base as regular passengers onboard other flights;

3) The plane is flown by two units: one belongs to the manufacturer and the other to the buyer. They check for conformity, sign the documents, and jointly fly the plane, in order for the manufacturer and the buyer to share immediate feedback on the plane's performance while airborne;

4) The plane is flown by a contracted pilot unit, which performs the duty as a third party payed by the buyer or by both the buyer and the manufacturer. This unit also includes a member of the buyer. They reach the manufacturer's base, the buyer's employee signs the documents, and then the plane is flown to the Company's headquarters or hub.

I assume each Company has its own policy in this regard, but which one of these procedures do you think is the most common? Thanks!
Typically the customer will travel to the manufacturers location for a final inspection and acceptance of the new aircraft. This includes one or several test flights with staff of both the manufacturer and the customer on board, thorough systems checking and final modifications if necessary. The acceptance of the aircraft is then made official by signing off a pack of papers. 

Then the customer transfers the final sum of money to the manufacturer and the aircraft is signed over to the customer. The delivery flight is typically operated solely by the customer's staff, however if it is the first aircraft of the specific type for the customer, the manufacturer may send training staff along for final training of the ground staff at the customers location if agreed so.